integrated analysis of data from mrc fisheries monitoring ...€¦ · the lao lee trap fishery...

Integrated Analysis of Data from MRC Fisheries Monitoring

Programmes in the Lower Mekong Basin

ISSN: 1683-1489

Mekong River Commission

MRC Technical PaperNo. 33

August 2013

C a m b o d i a . L a o P D R . T h a i l a n d . V i e t N a m

For sustainable development

Integrated Analysis of Data from MRC Fisheries Monitoring

Programmes in the Lower Mekong Basin

Mekong River Commission

MRC Technical PaperNo. 33

August 2013

Published in Phnom Penh, Cambodia in July 2013 by the Mekong River Commission

Cite this document as:

Halls, A.S.; Paxton, B.R.; Hall, N.; Hortle, K.G.; So, N.; Chea, T.; Chheng, P.; Putrea, S.; Lieng, S.; Peng Bun, N.; Pengby, N.; Chan, S.; Vu, V.A.; Nguyen Nguyen, D.; Doan, V.T., Sinthavong, V.; Douangkham, S.; Vannaxay, S.; Renu, S.; Suntornratana, U.; Tiwarat, T. and Boonsong, S. (2013). Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin. MRC Technical Paper No. 33, Mekong River Commission, Phnom Penh, Cambodia, 130pp. ISSN: 1683-1489.

The opinions and interpretations expressed within are those of the authors and do not necessarily reflect the views of the Mekong River Commission.

Cover Photo: J. Garrison

Editors: T. Hacker, T.R. Meadley and P. Degen

Graphic design and layout: C. Chhut

Office of the Secretariat in Phnom Penh (OSP)576 National Road, #2, Chak Angre Krom,

P.O. Box 623, Phnom Penh, CambodiaTel. (855-23) 425 353 Fax. (855-23) 425 363

Office of the Secretariat in Vientiane (OSV) Office of the Chief Executive Officer 184 Fa Ngoum Road, P.O. Box 6101,

Vientiane, Lao PDRTel. (856-21) 263 263 Fax. (856-21) 263 264

© Mekong River CommissionE-mail: [email protected]: www.mrcmekong.org

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Table of contents

List of Tables ........ ...................................................................................................................................vList of Figures ...... ................................................................................................................................ viiAbbreviations and Acronyms.. ............................................................................................................... xiGlossary of parameters ......................................................................................................................... xiiGlossary ............................ .................................................................................................................. xiiiAcknowledgements ............................................................................................................................. xviSummary .............. .............................................................................................................................. xvii1. Introduction .... ....................................................................................................................................1 1.1 Background ..............................................................................................................................1 1.2 The aims of the paper ...............................................................................................................2 1.3 Relevance to FEVM Logframe Outputs and Activities ............................................................2 1.4 Structure of the paper ...............................................................................................................2

2 The Cambodian Dai Fishery Monitoring Programme .......................................................................3 2.1 Introduction ..............................................................................................................................3 2.2 Description of the fishery .........................................................................................................3 2.3 Monitoring programmes ..........................................................................................................5 2.4 Status and trends of resources ..................................................................................................6 2.4.1 Catch composition .......................................................................................................6 2.4.2 Trends in species composition and diversity ...............................................................7 2.4.3 Trends in catch, indices of abundance and biomass and fish size (weight) .................7 2.5 Hydrological influences ..........................................................................................................10 2.6 Management effects ...............................................................................................................11 2.7 Conclusions ............................................................................................................................11

3. The Lao Lee Trap Fishery Monitoring Programme .........................................................................13 3.1 Introduction ............................................................................................................................13 3.2 Description of the fishery .......................................................................................................13 3.3 Monitoring programmes ........................................................................................................13 3.4 Status and trends ....................................................................................................................17 3.4.1 Catch composition .....................................................................................................17 3.4.2 Trends in species composition and diversity .............................................................17 3.4.3 Inter-annual variation in relative biomass and hydrological effects ..........................17 3.4.4 Intra-annual variation and hydrological effects .........................................................20 3.5 Conclusions ............................................................................................................................23

4. Fish Abundance and Diversity Monitoring Programmes (Small-Scale Artisanal Fisheries)............25

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4.1 Introduction ............................................................................................................................25 4.2 Monitoring programmes .........................................................................................................25 4.3 Resource status and trends .....................................................................................................30 4.3.1 Species composition ..................................................................................................30 4.3.2 Trends in species diversity ........................................................................................31 4.3.3 Trends in relative fish abundance and biomass indices .............................................36 4.3.4 Trends in growth .......................................................................................................38 4.3.5 Abundance, biomass, growth and flooding ...............................................................41 4.3.6 Other sites and species-wise analyses ........................................................................41 4.4 Conclusions .............................................................................................................................41

5. Larvae Density Monitoring Programme ...........................................................................................45 5.1 Introduction ............................................................................................................................45 5.2 Monitoring programmes .........................................................................................................45 5.3 Status and trends .....................................................................................................................47 5.3.1 Species composition ..................................................................................................47 5.3.2 Trends (all species) ....................................................................................................49 5.3.3 Trends by species .......................................................................................................52 5.4 Origin of ichthyoplankton drift ..............................................................................................57 5.5 Summary and conclusions ......................................................................................................57

6. Integrated analyses ...........................................................................................................................61 6.1 Introduction ............................................................................................................................61 6.2 Methodology ...........................................................................................................................62 6.2.1 The timing and extent of fish migrations ...................................................................62 6.2.2 Spawning locations ....................................................................................................62 6.2.3 Recruitment effects on stocks migrating from the TS-GL .........................................63 6.2.4 Extent of fish migrations from the TS-GL .................................................................63 6.2.5 Extent of flood effects on fish growth ........................................................................64 6.2.6 Management effects ...................................................................................................64 6.2.7 Selected species ..........................................................................................................65 6.3 Results ....................................................................................................................................66 6.3.1 Fish migrations ...........................................................................................................66 6.3.2 Spawning locations ....................................................................................................75 6.3.3 Recruitment effects on stocks migrating from the TS-GL .........................................78 6.3.4 Extent of fish migrations from the TS-GL .................................................................85 6.3.5 Extent of flood effects on fish growth ........................................................................88 6.3.6 Management effects and recruitment .........................................................................89 6.4 Summary and conclusions ......................................................................................................91

7. Conclusions and recommendations ..................................................................................................95

8. References ..... .................................................................................................................................101

9. Annex ............ .................................................................................................................................105

Integrated Analysis of Data from MRC Fisheries Monitoring Programmes in the Lower Mekong Basin

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List of Tables

Table 1 Estimates of total annual catch 1938–1988 ............................................................................ 5

Table 2 Species composition of the catch for the 2009–10 fishing season ......................................... 6

Table 3 Sites monitored under both the AMCF and FEVM catch monitoring programmes (2003–2010) .......................................................................................................................... 29

Table 4 Summary statistics for the catch monitoring programmes ................................................... 30

Table 5 Annual trends in estimates of species richness indices ........................................................ 33

Table 6 Annual trend in estimates of relative abundance, biomass and mean body weight .............. 38

Table 7 Estimates of geometric (GM) and arithmetic (AM) mean daily larvae density at the Mekong and Tonle Sap sampling locations, Cambodia, between June and September, 2002–2009 . ......................................................................................... 52

Table 8 Species exhibiting peaks in their larvae density estimates at the Mekong (MK) and Tonle Sap (TS) sampling locations in 2005 and 2008 . .................................................. 55

Table 9 Characteristics of species exhibiting peak larvae densities in 2005 and 2008 at the Tonle Sap and Mekong River sampling locations ....................................................... 56

Table 10 ANOVA results to test the dependence of loge-transformed larvae density (LNTS) in the Tonle Sap on inflowing volume of water (Q) accounting for differences among species (SP) ........................................................................................................................... 59

Table 11 The species selected for the correlation/function analysis. ................................................... 65

Table 12 Coefficients of linear regressions between estimates of larvae density in the Mekong River at Phnom Penh ....................................................................................................................... 76

Table 13 Coefficients of linear regressions between estimates of larvae density in the Tonle Sap at Phnom Penh and spawning stock biomass at the 10 locations ............................................. 77

Table 14 Regression coefficients of the linear relationship between estimates of the arithmetic mean daily larvae density-based recruitment index and loge-transformed dai catch rates .... 84


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Table 15 Regression coefficients of the linear dependence of relative spawning stock biomass at locations in the LMB ........................................................................................................ 86

Table 16 Regression coefficients of the linear dependence of relative abundance of spawning stock size at locations in the LMB ................................................................................................. 87

Table 17 Regression coefficients of the linear dependence of mean body weight of species sampled at fisher catch monitoring locations in the basin during February each year on the flood extent and duration in the TS-GL system ......................................................... 88

Table 18 Results of the GLM to test the dependence of dai catch rates on the quantity of fence ........ 89

Table 19 Statistics of confiscation and destruction of illegal fishing gears (2000–2009). ................. 105

Table 20 Percentage contributions of fish species to total catch weight reported under the fisher catch monitoring programmes, all gears and habitats ............................................... 106

Table 21 Monthly estimates of catch weight (kg) at the fisher catch monitoring sites (2003–2010) ................................................................................................................ 117

Table 22 Monthly estimates of the number of fish caught at the fisher catch monitoring sites (2003–2010) ................................................................................................................ 118

Table 23 Monthly estimates of the mean weight (kg) of fish caught at the fisher catch monitoring sites (2003–2010) ............................................................................................. 119

Table 24 Monthly estimates of the number of species reported (S) at the fisher catch monitoring sites (2003–2010) ............................................................................................. 120

Table 25 Monthly estimates of the Margalef index at the fisher catch monitoring sites (2003–2010) ........................................................................................................................ 121

Table 26 Monthly estimates of the species richness index (SRI) at the fisher catch monitoring sites (2003–2010) ....................................................................................................................... 122

Table 27 Monthly estimates of fisher catch rates (No/day) at the fisher catch monitoring sites (2003–2010) ........................................................................................................................ 123

Table 28 Monthly estimates of fisher catch rates (kg/day) at the fisher catch monitoring sites (2003–2010) ........................................................................................................................ 124

Table 29 Pearson coefficients for correlations between average daily catch rates (kg/day) by month at fisher catch monitoring locations. ................................................................... 125

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List of figures

Figure 1 The stationary trawl or (Loh Dai) fishery of the Tonle Sap-Great Lake (TS-GL) System, Cambodia . ..............................................................................................................................4

Figure 2 Illustration of the within-season variation in daily catch rates for the 2000–01 season .......7

Figure 3 Mean loge-transformed dai catch rates (kg/dai/day) values by lunar phase for the seasons 1997–98 to 2008–09 ..............................................................................................................8

Figure 4 Inter-annual trends in (a) total catch, (b) effort and (c) CPUE (1997–08 to 2009–10) .........9

Figure 5 Trends in mean fish weight (all species combined) and the flood index .............................10

Figure 6 The Location of the Lee trap fishery monitoring programme in southern Lao PDR ...........15

Figure 7 Species composition of the sampled catch from lee traps in Hoo Som Yai Channel, 2009 ...........................................................................................17

Figure 8 The average multispecies assemblage catch rate in the Hoo Som Yai Channel, 1997–2009 ...........................................................................................................................18

Figure 9 Estimates of CPUE by sampling year for the 14 species monitored from 1997–2009. .......19

Figure 10 Average multi-species catch rate in June each year (1997–2008) plotted as a function of mean water level at Pakse in the same month .....................................................................20

Figure 11 Mean daily lee trap CPUE for the multi-species assemblage migrating through the HSY channel and water level measured at Pakse ..........................................................21

Figure 12 Estimates of daily loge-transformed CPUE for the most frequently caught species in the HSY in 2008 plotted as a function of water level at Pakse .......................................22

Figure 13 The locations of the AMCF catch monitoring programme (2003–2005). ............................27

Figure14 The locations of the FEVM catch monitoring sites (2007–2010). .......................................28

Figure 15 An example comparison of the log-linear relationship between monthly estimates of S and sampling effort measured in terms of N and fishing days (D) for the Banfang site, Cambodia, monitored under the AMCF programme (2003–2005). .....................................32


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Figure 16 Intra-annual (monthly) variation in the estimates of the Margalef and SRI species richness indices at sites monitored under both the AMCF and FEVM programmes .........................................................................................................................34

Figure 17 Monthly estimates of the Margalef and SRI species richness indices at sites monitored under both the AMCF and FEVM programmes ..................................................................35

Figure 18 Average monthly variation in the indices of fish abundance and biomass at the 10 sites monitored under the AMCF and FEVM programmes (2003–2010). ...................................37

Figure 19 Monthly estimates of the relative fish abundance and biomass indicated by loge-transformed average fisher catch rates per day at those sites monitored under both the AMCF and FEVM programmes. ..................................................................39

Figure 20 Average monthly variation in mean fish weight and monthly estimates of mean fish weight at sites monitored under both the AMCF and FEVM programmes. ..................40

Figure 21 Estimates of indices of average fish abundance, biomass and mean weight in February each year, plotted as a function of the flood index for the six sites in Cambodia ...............43

Figure 22 The location of the fish larvae density monitoring sites in Cambodia and Viet Nam ..........46

Figure 23 Species composition of larvae samples taken from the Tonle Sap and Mekong River sampling sites 2002–2009 ...................................................................................................48

Figure 24 The number of species identified in larvae samples taken between June and September each year plotted as a function of the number of sampling days during the same period. ...49

Figure 25 Daily estimates of mean larvae density in the Tonle Sap and Mekong River, Cambodia, 2002–2009 ...........................................................................................................................50

Figure 26 Estimates of mean loge-transformed daily larvae density between June and September for the Mekong river and Tonle Sap, 2002-2009 .................................................................51

Figure 27 Estimates of arithmetic mean daily larvae density (June–September), 2002 – 2009, all species. ............................................................................................................................52

Figure 28 Mean daily larvae density estimates (x 1000) between June and September, 2004–2009 for the Tonle Sap sampling site . ..........................................................................................53

Figure 29 Mean daily larvae density estimates (x 1000) between June and September, 2004–2009 for the Mekong river sampling site ..................................................................54

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Figure 30 Frequency of peak larvae density by year for species recorded in samples from the Tonle Sap and Mekong River monitoring sites ....................................................54

Figure 31 Annual flood start, rise rate (FRR) at Kompong Luong, and duration in the TS-GL system. ............................................................................................................59

Figure 32 Annual maximum water level at Pakse, Lao PDR and Kompong Luong in the Great Lake, Cambodia. ...............................................................................................60

Figure 33 The generalized life-cycle and migration model for important whitefish species in the LMB ...........................................................................................................................61

Figure 34 Loge-transformed average monthly fisher catch rates by site for Cirrhinus lobatus and Henicorhynchus siamensis ...................................................................................................69

Figure 35 Loge-transformed average monthly fisher catch rates by site for Labeo chrysophekadion and Puntioplites proctozystron .............................................................................................70

Figure 36 Loge-transformed average monthly fisher catch rates by site for Cirrhinus microlepis and Poropuntius malcolmi ..................................................................................................71

Figure 37 Loge-transformed average monthly fisher catch rates by site for Cosmochilus harmandi and Yasuhikotakia modesta ...........................................................72

Figure 38 Loge-transformed average monthly fisher catch rates by site for Pangasius pleurotaenia and Pangasius larnaudii ......................................................................................................73

Figure 39 Loge-transformed average monthly fisher catch rates by site for Pangasius conchophilus and Hemibagrus nemurus .............................................................74

Figure 40 Estimates of the annual recruitment index, RI for the TS-GL system, 2002–2009 calculated as the product of the arithmetic mean (AM) or geometric mean (GM) daily

larvae density estimate, the mean daily inflow of water and inflow duration (days) ...........78

Figure 41 Loge-transformed dai catch rates (2004–05 to 2009–10) plotted as a function of the annual recruitment index, RI estimated arithmetic mean daily larvae density and

geometric mean daily larvae density between June and September each year.....................79

Figure 42 Observed and predicted dai catch rates estimated as the product of the arithmetic (AM) or geometric mean (GM) daily larvae densities (June to September), the mean daily flow into the TS-GL system ................................................................................................................80

List of Figures


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Figure 43 Estimated larvae survival rates applied to the arithmetic mean larvae density to generate the observed dai catch rates for the observed mean fish weights between 2004 and 2009. .......................................................................................................80

Figure 44 Predicted survival rates of larvae plotted as a power function of the larvae recruitment index and equivalent instantaneous natural mortality rates plotted as a function of loge-transformed recruitment index .....................................................................................81

Figure 45 Observed versus predicted dai catch rates. The upper figure shows catch rates predicted using arithmetic mean larvae density estimates, the lower figure shows

the geometric-mean based equivalent .................................................................................82

Figure 46 Loge-transformed dai CPUE plotted as a function of the arithmetic (top) and geometric (bottom) mean daily larvae density-based recruitment index ..............................................83

Figure 47 Recruitment in year y+1 and spawning stock biomass (SSB) indicated by dai catch rates in season y/y+1. ..................................................................................................90

Figure 48 Recruits (RI) per spawner index plotted through time. .......................................................91

Figure 49 Mean R2 value with S.E bars by size category for the species listed in Table 14 (except Panagsius sp. 1–3) ..............................................................................................................93

Figure 50 Mean weight of fish caught by the dai fishery plotted as a function of the TS-GL Flood Index (FI) for (i) 2003–2004 to 2009–2010 ........................................................................94

Figure 51 Relative biomass of some important Mekong species on the IUCN list of endangered species indicated by dai fishery catch rates. .........................................................................96

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Abbreviations and acronyms

AM Arithmetic MeanAMCF Assessment of Mekong Capture Fisheries (Programme)AMSL Above mean sea levelANOVA Analysis of varianceCAS Catch Assessment SurveyCNY Chinese New YearCPUE Catch per unit of effortDDM Density-Dependent MortalityDFMP Dai Fishery Monitoring ProgrammeDoF Department of FisheriesFADMP Fish Abundance and Diversity Monitoring ProgrammeFEVM Fisheries Ecology Valuation and MitigationFI Flood IndexFiA Fisheries AdministrationFLDMP Fish Larvae Density Monitoring ProgrammeGFL Great Fault LineGLM General Linear ModelGM Geometric MeanHSY Hoo Som Yai (channel)IFRDC Inland Fisheries Research and Development Center IFReDI Inland Fisheries Research and Development InstituteIUCN International Union for the Conservation of NatureLARReC Living Aquatic Resources Research Center LEK Local Ecological KnowledgeLMB Lower Mekong BasinLTMP Lee Trap Monitoring ProgrammeMFCF Management of the Freshwater Capture Fisheries (Programme)MFD Mekong Fish DatabaseMRC Mekong River CommissionMRCS Mekong River Commission SecretariatRI Recruitment IndexRIA2 Research Institute for Aquaculture 2 SD Standard deviationSE Standard errorSSB Spawning stock biomassTSBR Tonle Sap Biosphere ReserveTS-GL Tonle Sap-Great LakeUNESCO United Nations Educational Scientific and Cultural Organisation


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Glossary of parameters

C CatchCPUE Catch Per Unit of EffortD Fishing daysF Instantaneous fishing mortality rateFENCE Quantity of fence gear confiscated FRR Flood rise rate (m day-1)H Shannon Diversity IndexIMargalef Margalef’s IndexLmax Maximum reported length of the speciesLNTS Loge-transformed larvae density in the Tonle Sap (larvae m-3)lp Lunar phase (1–4)m Calendar monthn Sample sizeN, n Fish abundance (number of fish) or number of fish in the sample or number of daysp Probability of committing a Type I or II Errorq Catchability coefficientQ Flow (m3s-1)r Dai rowr Correlation coefficientR2 Coefficient of determinationRI Recruitment IndexRIAMTSY Arithmetic mean recruitment index in year yRIy The recruitment index in year yRPS Recruits per spawnerS Species richnessSmax Maximum species richnessSP Species code used in ANOVATL Total lengthWL Water levely Yield or yearΑ, a ConstantΒ, b Coefficient

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Glossary

Analysis of variance Analysis of variance (ANOVA) is a collection of statistical models, and their associated procedures, in which the observed variance in a particular variable is partitioned into components attributable to different sources of variation. In its simplest form ANOVA provides a statistical test of whether or not the means of several groups are all equal, and therefore generalizes t-test to more than two groups. Doing multiple two-sample t-tests would result in an increased chance of committing a type I error. For this reason, ANOVAs are useful in comparing two, three or more means.*

Arithmetic mean The central tendency of a collection of numbers taken as the sum of the numbers divided by the size of the collection*

Blackfish Species that possess morphological and physiological adaptations to extreme environmental conditions including low dissolved oxygen concentrations, and desiccation.

Catchability coefficient The proportion of the population removed by one unit of effort.Coefficient A multiplicative factor in some term of an expression.Coefficient of determination

The coefficient of determination R2 is used in the context of statistical models whose main purpose is the prediction of future outcomes on the basis of other related information. It is the proportion of variability in a data set that is accounted for by the statistical model. It provides a measure of how well future outcomes are likely to be predicted by the model.*

Correlation Linear relationship between two variables, neither assumed to be functionally dependent upon one another****.

Delury Depletion Model A method to estimate animal abundance by monitoring how indices of abundance (e.g. catch rates) decline in response to cumulative fishing effort.*****

Flood Index A quantitative description of the extent and duration of flooding corresponding to the area beneath and the area-duration curve above mean flood levels.

Functional Dependence Functional dependence exists when the magnitude of one (dependent) variable is determined by (is a function of) the magnitude of a second (independent) variable****.

General Linear Model (GLM)

The general linear model incorporates a number of different statistical models.* In this document GLM provides a general version of multiple linear regression where explanatory variables take the form of factors and covariates.


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Geometric mean The central tendency or typical value of a set of numbers. In this case estimated as arithmetic mean of the natural logs of the numbers.

Lunar phase or (lunar quarter)

Lunar quarters relate to four consecutive seven day periods starting from the new (dark phase) moon. Quarter 2, when catch rates in the dai fishery are observed to peak, corresponds to the period of approximately 7–14 days after the new moon when between approximately 50–100 % of the moon is visible. This period between what are commonly termed the first quarter and full moon phases is also known as the ‘Waxing Gibbous’ phase.

Multivariate (analysis) Analysis of multiple variables simultaneously.*Pearson correlation coefficient

A measure of the strength of the linear relationship between two variables.*

Population dynamics Population dynamics is the branch of life sciences that studies short-term and long-term changes in the size and age composition of populations, and the biological and environmental processes influencing those changes. Population dynamics deals with the way populations are affected by birth and death rates, and by immigration and emigration, and studies topics such as ageing populations or population decline.*

Primary production Primary production is the production of organic compounds from atmospheric or aquatic carbon dioxide, principally through the process of photosynthesis, with chemosynthesis being much less important. Almost all life on earth is directly or indirectly reliant on primary production. The organisms responsible for primary production are known as primary producers or autotrophs, and form the base of the food chain.*

Recruitment The number of fish (recruits) added to the exploitable stock, in the fishing area, each year, through a process of growth (i.e. the fish grows to a size where it becomes catchable) or migration (i.e. the fish moves into the fishing area).**

Reophilic A preference to live in fast moving water.Shannon Diversity Index The Shannon Diversity index, sometimes referred to as the Shannon-

Wiener Index is one of several diversity indices that can be used to measure species diversity. The advantage of this index is that it takes into account the number of species and the evenness of the species. The index is increased either by having additional unique species, or by having a greater species evenness.*

Species richness Species richness is the number of different species in a given area. It is represented in equation form as S. Typically, species richness is used in conservation studies to determine the sensitivity of ecosystems and their resident species. The actual number of species calculated alone is largely an arbitrary number.*

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Standard deviation Standard deviation shows how much variation or "dispersion" exists from the average. A low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data points are spread out over a large range of values. The standard deviation of a statistical population, data set, or probability distribution is the square root of its variance.*

Standard error An estimate of that standard deviation, derived from a particular sample used to compute the estimate*

Survey stratification The process of dividing members of the population into homogeneous subgroups (stratum) before sampling to reduce sample variance.

Type I Error Falsely rejecting the null hypothesis when it is true.Univariate (analysis) The analysis of a single variable.Whitefish Migratory species intolerant of low dissolved oxygen conditions and

typically inhabit lotic (flowing water) environments.

* http://en.wikipedia.org** http://www.fao.org*** http://www.primer-e.com/index.htm**** Zar (1999)***** Hilborn & Walters (1992)


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Acknowledgements

The author is grateful to Norman Hall for their comments and suggestions that improved earlier drafts of this report. Particular thanks to Bruce Paxton and Norman Hall for providing extensive and carefully prepared materials and data for the lee trap and dry season gillnet fisheries in southern Lao PDR, and for the Cambodian dai fishery - much of which forms the cornerstone of this report. Many thanks to Ngor Pengby for helping compile and query the datasets for the dai fishery and fisher catch monitoring programmes, and for preparing maps. Thanks also to Matti Kumi, Jorma Koponen and John Forsius for their guidance and assistance in preparing the hydrological data. The efforts of numerous people that have been involved in the design and implementation of the monitoring programmes described here are gratefully acknowledged including the staff of the MRC Fisheries Programme, Inland Fisheries Research and Development Institute (IFReDI), Cambodia, Living Aquatic Resources Research Center (LARReC), Lao PDR, Inland Fisheries Research and Development Center (IFRDC), Thailand, Research Institute for Aquaculture 2 (RIA2), Viet Nam, as well as participating fishers.

The preparation of this paper was facilitated by the MRC Fisheries Programme with funding from DANIDA and SIDA.

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Summary

Monitoring the status and trends of fisheries resources in the lower Mekong basin (LMB) is required to provide a baseline from which to monitor any impacts of fisheries management and basin development activities including dam construction.

Four major monitoring programmes have been supported by the Mekong River Commission to help monitor the status and trends in the fisheries in the lower Mekong basin:

1. The Dai Fishery Monitoring Programme (DFMP), Tonle Sap, Cambodia (1994–2010);

2. The Lee Trap Monitoring Programme (LTMP) at the Khone Falls, southern Lao PDR (1994–2010);

3. The Fish Abundance and Diversity Monitoring Programme (FADMP) at up to 40 sites across the LMB (2003–2010); and

4. The Fish Larvae Density Monitoring Programme (FLDMP), Cambodia and Viet Nam (1999–2010).

Analyses of much of the data generated by these programmes had been undertaken, some of which had been published. However, only a limited amount of work has been done to construct time series of the data collected that are much needed to interpret long-term trends in fish resources and for providing baselines for impact monitoring purposes.

This report presents time series of indices of fish diversity, fish (and their larvae) abundance, biomass and size for the multispecies assemblage and for important species estimated from data collected at more than 50 locations in the LMB by these four monitoring programmes. Intra-annual variation and long-term trends in these indices were examined.

Correlations and functional dependencies in the indices through space and time were also examined and tested in an attempt to elucidate the extent of fish migrations and identify spawning locations in the basin, and to improve understanding of the life-cycles and dynamics of fish stocks in the basin.

Significant long-term (1997–2010) trends in the indices were not detected for the multispecies assemblage that seasonally utilizes the Tonle Sap-Great Lake (TS-GL) system, nor were changes in its species composition that might be attributable to increasing fishing pressure in response to a growing population. Even populations of some species that are included on the IUCN Red List of endangered species and caught in the TS-GL system have shown no apparent decline in relative biomass. Similarly, no significant trend in the biomass of fish migrating upstream at the Khone Falls in southern Lao PDR was detected between 1997 and 2009. Furthermore, no consistent trends in the indices of


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relative abundance, biomass or species richness were observed among 10 fisher catch monitoring locations that have been monitored between 2003 and 2010. However, relative fish biomass at many monitoring locations in the basin and reproductive success appears to have been relatively low since 2005–06 compared to earlier years. Significant declines in the relative biomass index for several species were also apparent at some locations, notably at Pres Bang on the Sekong River. The assertion that the diversity and biomass of the multispecies assemblage have declined significantly in the basin therefore remains contentious. Much will hinge on whether recent estimates of relative fish biomass in the system will recover to previous levels.

Most of the species selected for detailed assessment exhibit life cycles and migrations that are largely consistent with the general life cycle model described by previous workers. Migrations of several selected cyprinid and pangasiid catfish species appear to extend long distances upstream, at least as far as the uppermost monitoring site at Luang Prabang. However, the migrations of other cyprinids and pangasiid and bagrid catfish species appeared to be much more limited.

Fish migrations from the TS-GL system appear to be strongly linked to the lunar cycle as well as the amount of water remaining on the floodplain. A lunar response of fish migrations was not detected further upstream at the lee trap fishery in southern Lao PDR. Instead water level appears to be an important factor affecting the migrations of non-pangasiid species. The pangasiid catfish species selected for monitoring here appeared to be caught in larger quantities at lower flows.

Statistical attempts to identify spawning locations in the LMB were largely unsuccessful but the results of less formal analyses suggest that among others, Stung Treng province, Cambodia and the three tributaries in the Sesan basin are relatively important spawning locations for small cyprinids. The Srepok River also appears to provide important habitats for medium and large species of cyprinid and the Sesan and Sekong rivers also appeared to provide important habitats for pangasiid catfish. These locations are consistent with results of analyses of age distributions of larvae sampled at Phnom Penh. Thus, greater consideration might be given to conserving tributary habitat during basin development planning in the future but more research is also needed to fully understand the role of tributaries in the LMB in the lifecycles of important species.

The abundance and biomass of the multispecies assemblage that seasonally utilises the TS-GL system responds significantly to the transport of larvae from upstream spawning locations and the extent and duration of flooding indicated by the flood index (FI). It appears that record catch rates recorded for the dai fishery in 2004–05 and 2005–06, and apparent elsewhere in the basin in 2005 were in response to very high rates of recruitment during 2004 and 2005, rather than growth effects.

These high levels of recruitment could not be linked to management efforts to conserve or rebuild spawning stock biomass by confiscating illegal gear in the TS-GL system. Rather, it appears that a combination of spawning success, larvae survival and rates of transport were important. Water levels rose rapidly in 2005, second only to the rates observed in 2002. This may have stimulated upstream spawning migrations and benefited larvae survival and transport. However, reasons for the very high rates of recruitment estimated for Henicorhynchus species in 2004 remain perplexing. A

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Summary

closer examination of hydrological and water quality parameters across the geographic range of these species and particularly during the spawning season at likely spawning locations, including the Sesan basin, appears warranted.

Many of the analyses described in this document were hampered by the low precision of index estimates. Therefore, consideration might be given to reviewing the size of samples taken by each monitoring programme to detect acceptable minimum detectable differences in index estimates. Other recommendations to improve the four monitoring programmes and their databases are described.


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1. Introduction

1.1. Background

Four major monitoring programmes have been supported by the Mekong River Commission to help monitor the status and trends in the fisheries in the lower Mekong basin:

1. The Dai Fishery Monitoring Programme (DFMP), Tonle Sap, Cambodia (1994–2010);

2. The Lee Trap Monitoring Programme (LTMP) at the Khone Falls, Lao PDR (1994–2010);

3. The Fish Abundance and Diversity Monitoring Programme (FADMP) at up to 40 sites across the LMB (2003–2010); and

4. The Fish Larvae Density Monitoring Programme (FLDMP), Cambodia and Viet Nam (1999–2010).

Since December 2007, the FADMP included two additional monitoring locations (Hat and Hadsalao villages) in southern Lao PDR. Between 1994 and 2007 catch rates of between 5 and 10 gillnet fishers were monitored at these two locations for between 13 and 15 days during the dry season each year around the time of the Chinese New Year (CNY). Because the CNY falls on a different calendar day each year depending on the moon phase, the monitoring period has changed each year between 20th January and 2nd March (Paxton, undated). Since December 2007, catch rates at these sites have been monitored daily under the FADMP.

As well as providing a means to monitor the status and trends of fisheries resources in the basin, these programmes also provide a baseline from which to monitor any impacts of fisheries management and basin development activities including dam construction.

Detailed analysis of the data generated by DFMP programme have been reported (Halls et al., 2011). Preliminary analyses of the data collected under the LTMP and dry season gillnet fishery monitoring in southern Lao PDR have also been undertaken (Paxton, undated) and reported by MRC (2010). Whilst analyses of data generated by the FADMP and the FLDMP have been reported (e.g. Doan et al., 2006; Nguyen et al., 2006 and Hortle et al., 2005), less work had been done to construct time series of the data collected. Such series are not only important for assessing and interpreting trends in indices of larvae and fish abundance and diversity but also form important baselines for impact monitoring purposes.


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Moreover, comparing variation in these indicators among monitoring sites can potentially provide information on the spatial extent of stocks as well as the extent over which resources respond in a similar manner to inter-annual variation in environmental conditions including hydrology. Comparing time series from these four monitoring programmes in a more integrated manner assists the interpretation of their respective trends.

1.2 The aims of the paper

This paper aims to describe the status and trends of fisheries resources at monitoring locations across the Lower Mekong basin. It also explores the spatial and temporal dynamics of widely abundant species in an attempt to improve knowledge and understanding of fisheries resources in the LMB for management and basin development planning purposes. Catch rate data collected at Hat and Hadsalo villages prior to 2007 have not been included here because of the short and variable timing of monitoring activities at these locations, making it difficult to draw valid comparisons with data from the other surveys. Catch rate trends for Hadsalo are illustrated in MRC (2010).

1.3 Relevance to FEVM Logframe Outputs and Activities

The research will contribute to FEVM Logframe Outputs 1, 3 and 5: Improved information on the ecology of the fisheries of the LMB and models for basin planning purposes are available to basin planners and development agencies. Improved institutional capacity to monitor and evaluate fisheries resource status and trends. FEVM Logframe Activities addressed are: 1.2 Describe trends in fish abundance and diversity in the basin; 3.3 Develop models to predict the effects of modified flows on fisheries; Train national agencies in fisheries assessment methods.

1.4 Structure of the paper

The following Sections 2 to 5 contain descriptions of the four monitoring programmes and where relevant the fisheries they sample. Important species sampled by each programme are identified. Inter-and intra-annual variations in indices of diversity, abundance, and where relevant, biomass and fish size, are examined. For the FADMP, monthly estimates of each index for each monitoring location are tabulated in the Annex (Table 21–Table 28). Section 6 draws upon data collected under each monitoring programme. It seeks correlations and functional dependencies in the indices through space and time in an attempt to reveal the extent of fish migrations and the location of spawning areas in the basin, as well as to improve understanding of the life-cycles and dynamics of fish stocks in the basin. Each section ends with a summary and conclusions. Overall study conclusions are drawn and recommendations made in Section 7.

2 The Cambodian Dai Fishery Monitoring Programme1

2.1 Introduction

The dai fishery on the Tonle Sap River, which was established almost 140 years ago, is an important component of the Tonle Sap Great Lake (TS-GL) fishery, targeting the migrations of a multi-species assemblage of fish that migrates from the Great Lake to the Mekong main channel with the receding floodwaters each year.

The dai fishery contributes up to 33,000 tonnes or 7 % of Cambodia’s total annual landings of fish from the Mekong Basin estimated to be in the region of 480,000 tonnes per annum (Hortle, 2007), valued at more than US$6 million in 2006. The remaining proportion of the country’s total catch is taken using large-scale fence and barrage traps, and by small and middle-scale fisheries employing seines, gillnets, small trawls, bamboo traps, cast nets and hook and line (Baran, 2005).

The dai fishery provides important seasonal employment opportunities for more than 2,000 rural people and supplies the essential ingredient for prahock, a fermented paste which is an important protein source for many, particularly towards the end of the dry season when fish is scarce (Halls et al., 2007).

2.2 Description of the fishery

The fishery is located in the lower section of the Tonle Sap River spanning more than 30 km across the municipality of Phnom Penh and Kandal Province (Figure 1). Dai nets (stationary trawls) are arranged in up to 15 separate rows of between one and seven nets anchored perpendicularly to the channel, with the net mouths facing upstream. The most upstream Row (15) is located approximately 35 km from Phnom Penh. These positions have remained largely unchanged for more than a century and may have been chosen to maximize catch rates determined by river morphology and hydrology.

The dai fishery primarily targets small cyprinids of the Cirrhinus, Labiobarbus and Henicorhynchus genera, collectively known as trey riel in Khmer. Other species making an important contribution to landings are pelagic river carp (Paralaubuca barroni), and species of loach. The families Cyprinidae and Cobitidae dominate the landings. Their species are targeted as they migrate from the TS-GL system and surrounding floodplains to what are hypothesized to be dry season refuge habitat (e.g. deep pools) in the main channel as water levels fall between October and March. As water levels begin to rise at the start of the next wet season (April–May), it is hypothesized that adults migrate upstream to spawn and then return back downstream with their larvae and juvenile progeny to the TS-GL system and other floodplain feeding habitat. Further details of the operations and management of the fishery are described by Halls et al. (2011).

1 This section draws heavily from Halls et al., (2011); Halls and Paxton, (2010).


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Figure 1 The stationary trawl or (Loh Dai) fishery of the Tonle Sap-Great Lake (TS-GL) System, Cambodia. The solid yellow circles indicate the position of a row of dais.

The Lao Lee Trap Fishery Monitoring Programme

2.3 Monitoring programmes

The fishery has been monitored intermittently since the 1930s but continuously and intensively during the last decade providing the main source of data and information to monitor trends in the fisheries resources (fish populations) that seasonally utilize the TS-GL system and beyond. These monitoring programmes have also provided estimates of total aggregated monthly and seasonal catches and their monetary value for management and administrative purposes.

Ad hoc surveys and regular ‘logbook’ monitoring undertaken between the late 1930s to 1980s generated total annual catch estimates of between approximately 13,500 to 18,000 tonnes (Table 1). Regular monitoring using logbooks began in the 1980s supplemented by ad hoc surveys described by Nguyen and Nguyen (1991). However logbook monitoring by the Cambodian Fisheries Administration (FiA), formerly the Department of Fisheries (DoF), was regarded as unreliable because fishers under-reported their catch to influence licence costs.

Table 1 Estimates of total annual catch 1938–1988.

Season Total catch (tonn) No. of dais Reference1938–1939 13,568 106 Chevey and Le Poulain (1940)1962–1963 2,135 61 Fily and d'Aubenton (1965)1981–1993 5,000–12,839 75–97 DoF statistics1986–1988 7,413–18,026 86 Nguyen and Nguyen (1991)

Source: Lieng et al. (1995).

From 1994 to date, catch and effort variables and length-frequency data have been sampled daily during the fishing season (October to March) by the FiA using direct observation (enumerator) methods with the support of the Mekong River Commission’s (MRC) Fisheries Programme. This Catch Assessment Survey (CAS) provides species-wise estimates of: (i) total annual catch, (ii) indices of abundance and biomass (CPUE), (iii) mean weight and (iv) population size (age) structure.

The CAS samples CPUE and effort from randomly selected dai units, stratified by municipality (Kandal and Phnom Penh), lunar phase (peak and low catch phase) and dai type (high and low catch rate2). Total catch each month within each strata is then estimated as the product of the mean catch rate (catch per dai unit per day) and the total fishing effort (dai fishing days). These estimates are then summed across the strata to give estimates for the whole fishery, see (Halls et al., 2011; Ngor and van Zalinge, 2001). Catches are sub-sampled for species composition data to provide estimates of catch by species.

2 Based upon an incomplete census of average catch rates of every dai unit described by Ngor, (2000) and Ngor and van Zalinge, (2001).


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2.4 Status and trends of resources3

2.4.1 Catch composition

Since 1997–1998, 142 species of fish have been recorded in the dai landings, with a minimum of 66 in 1999–2000 and a maximum of 125 in 2002–2003. On average, 106 species are recorded during the fishing season. During 2009–2010, 122 species were reported. Fifteen species formed 90 % and 26 species formed 95 % of the estimated total catch for the season (Table 2).

Table 2 Species composition of the catch for the 2009–2010 fishing season. Only those species forming 95% of the catch by weight are included.

Species Name Catch (kg) Proportion of total catch % Cumulative %Cirrhinus lobatus 1,945,523 25.6 25.6Lobocheilos cryptopogon 1,383,575 18.2 43.9Paralaubuca barroni 766,256 10.1 54.0Labiobarbus lineatus 765,672 10.1 64.1Henicorhynchus siamensis 718,408 9.5 73.6Labiobarbus siamensis 258,955 3.4 77.0Labeo chrysophekadion 158,688 2.1 79.1Pangasius pleurotaenia 156,318 2.1 81.1Puntioplites proctozystron 149,138 2.0 83.1Thynnichthys thynnoides 115,169 1.5 84.6Syncrossus helodes 81,441 1.1 85.7Clupeichthys aesarnensis 76,937 1.0 86.7Yasuhikotakia modesta 76,768 1.0 87.7Cirrhinus microlepis 73,653 1.0 88.7Pangasius larnaudii 68,127 0.9 89.6Amblyrhynchichthys micracanthus 63,145 0.8 90.4Gyrinocheilus aymonieri 42,491 0.6 91.0Osteochilus lini 41,111 0.5 91.5Cosmochilus harmandi 40,241 0.5 92.0Belodontichthys truncatus 38,170 0.5 92.5Phalacronotus micronemus 37,350 0.5 93.0Cyclocheilichthys enoplus 36,291 0.5 93.5Boesemania microlepis 35,767 0.5 94.0Barbichthys nitidus 31,675 0.4 94.4Pangasianodon hypophthalmus 29,733 0.4 94.8Pangasius conchophilus 26,881 0.4 95.1

3 Effort data are regarded as reliable only from 1997–1998 onwards (Ngor Pengby pers. comm.), and therefore we present data only from this season to the most recent estimates (2009–2010).

2.4.2 Trends in species composition and diversity

Trends in species composition and diversity of the catches from the dai fishery have been the subject of detailed univariate and multivariate analyses, see (Halls et al., 2011; Halls and Paxton 2010; Baran et al., 2001). These studies indicate that the species dominating the catch have remained largely unchanged since the 1930s. Furthermore that apparent inter-annual variation in species composition and indices of diversity (species richness ' S ' and the Shannon-Weiner Diversity Index 'H ') are likely to be an artefact of sampling intensity and changes to the survey techniques, i.e. sample stratification and/or species identification, and therefore may not be biologically significant.

2.4.3 Trends in catch, indices of abundance and biomass and fish size (weight)

The dai fishery operates during the falling water period (October–March). During this fishing season, fish abundance, indicated by daily catch rates of sampled dai units, exhibits significant variation both between and within the six months comprising the fishing season. Catch rates can vary from approximately 1 kg.dai-1.day-1 to 80,000 kg.dai-1.day-1. Typically catch rates peak (mean = 4,538 kg.dai-1.day-1) during January (nine out of the 13 seasons) and are lowest (mean = 44 kg.dai-1.day-1) in October (eight out of 13 seasons), (Figure 2).

Figure 2 Illustration of the within-season variation in daily catch rates for the 2000–01 season. Source: Halls et al. (2011).



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Catch rates consistently peak during the second quarter of the lunar cycle and are lowest during the 4th quarter (Figure 3), (Halls et al., 2011). Here, the lunar quarters relate to 4 consecutive 7 day periods starting from the new (dark phase) moon. Quarter 2 therefore relates to the period of approximately 7–14 days after the new moon when between approximately 50–100% of the moon is visible. This period, between what are commonly termed the first quarter and full moon phases, is also known as the ‘Waxing Gibbous’ phase.

Figure 3 Mean loge-transformed dai catch rates (kg/dai/day) values by lunar phase for the seasons 1997–98 to 2008–09.

Source: Halls et al. (2011). Error bars give 95% confidence intervals around the mean.

These patterns suggest that fish migrations are influenced by the lunar cycle, and possibly water levels as peak migrations typically occur around January or December coinciding with the end of the flood season.

In the past 13 years, total catch (aggregated across species) by season has varied from between approximately 9,000 and 35,000 tonnes, with a mean of approximately 17,000 tonnes but with no obvious trend (Figure 4a). High catches were observed in 2000–01, 2004–05 and 2005–06. The


average number of active dais4 has ranged from approximately 57 to 68 dai units, with evidence of a decline through time (Figure 4b). Catch per dai per season – a crude index of fish biomass (Figure 4c) exhibits a similar coefficient of variation as catch per season (approximately 45–48 %) and there is also no obvious trend through time. Note that the catch, effort and CPUE estimates illustrated in Figure 4 differ slightly from those reported by Halls and Paxton (2010); Halls et al. (2011) because they were derived using the number of active dais reported by field enumerators during each month instead of the number of dais licensed to fish each year as reported by the FiA.

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Figure 4 Inter-annual trends in (a) total catch, (b) effort and (c) CPUE (1997–98 to 2009–10). The blue line in the CPUE figure illustrates seasonal variation in an index combining flood extent and duration

in the TS-GL system described by Halls et al. (2011).

4 An active dai is defined as a dai unit that is active (fishing) on the sampling day. A licensed dai is a dai unit that may legally operate (fish) during the fishing season. Note, dai units may not always be active either because catch rates are deemed too low for economically viable operation of the dai or because the dai cannot operate due to technical problems.

a)

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Estimates of mean weight, an indicator of growth performance, also exhibited considerable variation during the 13 year monitoring period but with no evidence of a trend (Figure 5).

2.5 Hydrological influences

With the exception of the estimates for 2004–05 and 2005–06 and perhaps also 2009–10, variations in the index of fish biomass appears to track the variation in the flood index – a composite measure of both the extent5 and duration of flooding in the TS-GL system, closely (Figure 4c). The variation in mean fish weight also appears to closely follow variation in the flood index (Figure 5). Similar responses have been found for those species that form the bulk of the catch, see (Halls et al., 2011;

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Figure 5 Trends in mean fish weight (all species combined) and the flood index (blue line) for the TS-GL

system (upper) and mean fish weight plotted as an exponential function of the flood index (lower). Source: Halls et al. (2011).

5 Flood extent is the area of land inundated above the long-term average inundated area, see (Halls et al., 2011 for further details).


Halls and Paxton, 2010). This suggests that the flood index is important for determining fish biomass through its effect on growth (mean weight). Feeding opportunities would be expected to be greater during longer and more extensive floods (Welcomme, 1985). Mean fish weights for 2004–05 and 2005–06 were largely consistent with the observed flood indices. Therefore, above average levels of recruitment were probably responsible for the very high catches and catch rates observed during these two seasons. Mean fish weight for 2009–10 was also consistent with the expected value for the flood index, suggesting that recruitment was particularly low during 2009. Indeed, estimates of the density of larvae derived from samples collected from the Mekong River were at historically low levels during 2009 (Section 5.3.2). These recruitment effects are also explored further in Section 6.2.3.

2.6 Management effects

The FiA confiscates illegal gears operated in the TS-GL system including (but not limited to) small mesh and bamboo fences, cylindrical traps and brush parks. During the peak of a compliance campaign in 2004, more than 1,700 km of small mesh fence was confiscated along with nearly 21,000 traps and 77,000 brush parks (Annex Table 19). These gear confiscations have been used to explain the very high catch rates observed in 2004–05 and 2005–06 (e.g. Hortle, 2005). These management effects are explored in more detail in Section 6.2.6.

2.7 Conclusions

The Cambodian stationary trawl or dai fishery of the TS-GL system contributes significantly to the country’s economy, food security and fishery-dependent livelihoods. It is the most intensively monitored inland fishery in south-east Asia providing important indicators of the status and trends of floodplain-dependent fisheries resources in Cambodia. There is currently no compelling evidence of a decline in the biomass index for the multispecies assemblage, mean fish weight or species composition through time that could be attributable to increasing fishing pressure in response to a growing population. Rather, it appears that the species that form the basis of the fishery respond strongly and rapidly to changes in flood intensity and duration measured by the flood index. Biomass responses appear to be mediated through variations in growth (mean weight) possibly in response to feeding opportunities. Above average levels of recruitment are likely to have been responsible for the very high catches observed during 2004–05 and 2005–06. Factors that might have been responsible for the high levels of recruitment during these two fishing seasons are examined in Section 6.


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3 The Lao Lee Trap Fishery Monitoring Programme

3.1 Introduction

Important fisheries are located at the Khone Falls, Champassak Province, southern Lao PDR. Here the mainstream of the Mekong River braids into 18 major channels before it flows over the GreatFault Line (GFL) – a geological fault that causes the river to drop 20 m over a distance of around10 km. An estimated 60,000 people live on the many islands at Khone Falls and fishing is an important component of their livelihood. Fishers utilize more than 40 different gear types (Baran et al., 2005). These include the semi-submerged lee traps (Paxton, undated).

3.2 Description of the fishery

An estimated 400 lee traps are set each year in the 18 channels of the Khone Falls (Warren et al., 2005). The traps are set into rapids to target upstream spawning migrations of fish, mainly catfish (Pangasiidae, Bagridae and Siluridae). Swimming against the rapids, fish eventually tire and are swept back into the trap (Plate 1). Channels are sometimes modified to obstruct successful upstream passage of fish. Fish are mostly caught at night and the fishers clear the traps in the morning. The traps also target small fish particularly cyprinids (Henicorhynchus spp.), (Paxton, undated). Chomchanta et al. (2000) list 22 species that are commonly caught in the lee traps. They separate them into two groups: Group 1 consisting of fishes migrating upstream (mostly Pangasiidae and Siluridae) and Group 2 consisting of fishes believed to be migrating downstream (Cyprinidae). The most important species by landing weight are Pangasius larnaudii and P. conchophilus. Warren et al. (2005) report that the fishery catches 40–50 fish species. The fishing season was believed to end in late June (Singhanouvong et al., 1996) but, investigations in 2008 revealed that fishing in some locations continues until early September until traps are either submerged or destroyed by rising waters (Sinthavong Viravong pers comms).


With financial support from the Government of Canada, monitoring of the lee trap fishery began in 1994 in the Hoo Som Yai (HSY) channel below the Khone (Figure 6 and Plate 2) (Singhanouvong, et al., 1996). The Hoo Som Yai is one of the smaller channels that pass over the Great Fault Line on the main stem of the Mekong River. It diverges from the Khonephapeng channel above the falls of the same name. The HSY then flows in a narrow vegetated channel between 10 and 20 m wide for roughly 800 m before rejoining the main channel another 600 m downstream of the falls in Northern Cambodia. Water depths in the predominantly bedrock channel vary between 0.5 m


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Plate 1 Harvesting fish from a lee trap in the Hoo Som Yai channel, southern Lao PDR Photos: B.R. Paxton and S. Viravong

over the dry season and roughly 3.5–4.0 m over the wet season (Singhanouvong, 1996). Although the Hoo Sahong to the west of the HSY is believed to be the most important of the estimated 18 channels that pass over the Great Fault Line in terms of its importance for fish migration because of its depth and width, the HSY is the most accessible for sampling purposes and was therefore selected as a monitoring site for this reason (Paxton, undated).

The monitoring programme aimed to estimate the relative abundance and biomass of fish migrating through the channel each year indicated by mean daily lee trap catch rates. Monitoring was conducted over a five-week period between May 24 and June 30 with samples collected three times each week. It was assumed that most fish migrations occur during this period. Catch rates during the monitoring period were estimated as the total catch landed on the 15 sampling days divided by the total number of lee traps sampled. The project also measured the volume of water flowing through the channel. Although no sampling was carried out in 1998 and 1999, monitoring resumed in 2000 under the newly-established Living Aquatic Resources Research Center (LARReC) in Vientiane, with financing from the Lao and Danish governments until 2004 and the Mekong River Commission since 2005. Since 2008, the monitoring period has been extended by three months until the end of September when the traps are either submerged or destroyed by rising flood waters (Paxton, undated).


Figure 6 The Location of the Lee trap fishery monitoring programme in southern Lao PDR


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Plate 2 The Hoo Som Yai Channel. Source: Paxton, undated.

Between 1994 and 1998, the total landings of each fisher were sorted into species or type, weighed and enumerated (Singhanouvong, 1996). From 1997 onwards, data only for 14 species deemed to be migratory were collected. Since 2008, catches of all species were once again recorded. Species belonging to the Henicorhynchus genus, known locally as the Pba Soi, were lumped into a single group. No fishing effort or catch weights were recorded prior to 1997, only catch rates. Further details of the catch monitoring and data storage and processing methods are described by Paxton (undated).

3.4.2 Trends in species composition and diversity

It is difficult to draw conclusions regarding trends in the species composition or diversity indicators for the multispecies assemblage migrating through the channel because of changes made to the sampling methodology and because for most years only selected species deemed migratory were sampled. Trends in the relative abundance of these 14 species are examined below.

3.4.3 Inter-annual variation in relative biomass and hydrological effects

The abundance of the multispecies assemblage migrating through the HSY channel has shown no detectable linear trend through time since 1997 (p = 0.42), (Figure 8). Average catch rates between 1997 and 2009 were approximately 14 kg trap-1 day-1. Catch rates fluctuated during this period by more than an order of magnitude, peaking like the Cambodian dai fishery in 2005, and were also relatively high in 2003.

Pangasius larnaudii

Bagarius yarrelli

Pangasius conchophilus

Labeo chrysophekadion

Hemisilurus mekongensis

Pangasius macronema

Amblyrhynchichthys micracanthus

Helicophagus leptorhynchus

Hemibagrus nemurus

Wallago attu

Hemibagrus wyckioides

Pangasius bocourti

Hemibagrus wyckioides

Henicorhynchus sp.

Figure 7 Species composition of the sampled catch from lee traps in Hoo Som Yai Channel, 2009. Only those species which comprised 95 % by weight of the total catch are shown.

3.4 Status and trends

3.4.1 Catch Composition

In 2009, Pangasius larnaudii formed more than 50 % of the sampled catch weight. Bagarius yarrelli, P. conchophilus and Labeo chrysophekadion contributed a further 22 %. Species belonging to the Henicorhynchus genus formed less than 1 % of the sampled catch weight (Figure 7).



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Inter-annual variation in the relative biomass of each species forming the multi-species assemblage was also high (Figure 9). Catch rates were highest in 2005 for nine of the 14 species, in 2003 for three species, and in 2001 and 2008 each for a single species. Some species shared similar catch rate trends for example, Belondontichthys dinema and Hemibagrus microphthalmus, both large: (Lmax6 = 100 – 130 cm and both carnivorous) and Helicophagus leptorhynchus (Lmax = 50 cm; carnivorous) and Panagsius conchophilus (Lmax = 120; omnivorous).

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Figure 8 The average multispecies assemblage catch rate in the Hoo Som Yai Channel, 1997–2009. No sampling in 1999.

6 Lmax refers to the maximum reported length of the species

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Figure 9 Estimates of CPUE by sampling year for the 14 species monitored from 1997–2009.



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No simple (linear) functional dependence of relative fish biomass migrating through the HSY channel in June each year on local water levels was found for the multispecies assemblage (Figure 10), nor for individual species except Hemisilurus mekongensis.

3.4.4 Intra-annual variation and hydrological effects

During 2008, when the monitoring programme was extended beyond June, there was evidence that catch rates varied significantly in response to hydrological conditions indicated by water level measured at Pakse (Figure 11). Catch rates peaked in July and August, not June as previously assumed (see above), and reached a maximum rate corresponding to the maximum water level. Intense migrations of Bagarius yarrelli were responsible for the peaks in catch rates observed at the start (23/06/2008) and towards the end (18/08/2008) of the fishing season. Unlike the Cambodian dai fishery, no evidence was found that catch rates of the multi-species assemblage varied significantly among the four quarters of the lunar cycle during 2008 (p = 0.63). .

0

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Figure 10 Average multi-species catch rate in June each year (1997–2008) plotted as a function of mean water level at Pakse in the same month.

The high catches (> 40 kg/trap/day) were observed in 2003 and 2005.

At the species level, estimates of the mean daily catch rates for six of the ten species caught in the HSY channel on at least 15 days during 2008 were also significantly dependent on water level measured at Pakse (Figure 12). The remaining four species (the Pangasius species and Cirrhinus molitorella) were conspicuously absent after water levels exceed approximately 9 m corresponding to the first week of August suggesting that their migrations are restricted to the early to mid-rising water phase. There was even some weak evidence that catch rates for the Pangasius species decline with increasing water level.

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Figure 11 Mean daily lee trap CPUE for the multi-species assemblage migrating through the HSY channel and water level measured at Pakse.

Estimates of CPUE were significantly dependent upon water level (R2 = 0.22; p < 0.001).



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Figure 12 Estimates of daily loge-transformed CPUE for the most frequently caught species in the HSY in 2008 plotted as a function of water level at Pakse.

The dependence of CPUE on water level was significant (p < 0.05) except for the Pangasius species and Cirrhinus molitorella.

3.5 Conclusions

Lee traps positioned in the HSY channel primarily target the migrations of large pangasiid, silurid and bagrid catfish as water levels in the channel rise each year. For the majority of species for which data were available, the relative biomass of fish migrating through the channel during 2008 appeared to be dependent upon local water levels, increasing and decreasing during the rising and falling water periods respectively. However, this dependency appears less pronounced or absent for C. molitorella and the four pangasiid species monitored. Unlike the other species that were observed in catches throughout the monitoring period of 2008, the migrations of these five species also appeared to occur only during the early to mid-rising water phase. Lunar influences on the migrations of the multispecies assemblage migrations could not be detected.

Catch rates would be expected to increase with water level (and flow) if gear catchability and/or migration stimulus or success increase with flow. Since the traps rely on fish becoming exhausted and falling back into them, their catchability (efficiency) would be expected to increase with flow. Swimming capacity is related to fish size and therefore smaller species would be expected to be more vulnerable to exhaustion in higher flows than larger species. However, no significant difference was found in the mean body weights of those species exhibiting and not exhibiting increasing catch rates with water level (p = 0.10). Therefore, the catch rate-water level response might instead reflect the effect of flow as migration stimulus. Those four species apparently not responding to flows measured at Pakse may begin their migrations further downstream where hydrological conditions may be different. Pangasiid catfish are reputed to be long distance migrant species, particularly Pangasius krempfi (Poulsen et al., 2004). Cirrhinus molitorella is also reported to be strongly migratory (Roberts, 1997).

The relative biomass of fish migrating through the HSY channel was estimated to be particularly high in 2003 and 2005. Catch rates peaked in 2005 for nine of the 14 species selected for monitoring, whilst the high relative biomass estimate for 2003 was attributable mainly to P. conchophilus P. larnaudii. No significant trend in relative biomass was apparent since 1997. The inter-annual variation in relative biomass of the multispecies assemblage, including the very high estimates for 2003 and 2005, were not apparently (linearly) dependent on local water levels measured at Pakse. Based upon measurements at Phnom Penh, the flood in 2003 started relatively late, rose relatively slowly and was relatively short in duration. The hydrological conditions in 2005 were unremarkable, except that water levels rose rapidly (approximately 62 mm day-1) second only to the rate observed in 2002 (64 mm day-1).

If the intra-annual variation in migration intensity observed during 2008 is typical of most years, it would suggest that the fishery should be monitored from May to at least the end of August, possibly to the end of September, in order to provide more accurate annual indices of relative fish biomass migrating through the HSY channel.



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4 Fish Abundance and Diversity Monitoring Programmes (Small-Scale Artisanal Fisheries)

4.1 Introduction

Routine monitoring of small-scale fishers in the LMB by the MRC began with the ‘Logbook Migration Monitoring’ survey from December 2000 to November 2001 abbreviated to ‘MM2001’ involving 44 fishers from the four riparian countries (Visser, 2004). The main objectives of the survey were to develop and pilot-test methods to collect catch data from individual fishers using logbooks for potential application on a wider scale, and to evaluate the reliability of fish migration behaviour reported by fishers under the Local Ecological Knowledge (LEK) survey undertaken during 1999. Further details of this pilot project and the results of preliminary analyses are described by Visser (2004) and Poulsen et al. (2004).

This pilot project led to the design and implementation of the ‘Fish Catch Monitoring Study’ under the MRC’s Assessment of Mekong Capture Fisheries (AMCF) Programme between April 2003 and December 2005 (Doan et al., 2006). Further refinement of the approach was attempted under the MRC’s Fisheries Ecology, Valuation and Mitigation (FEVM) Component, under a programme entitled ‘Fish Abundance and Diversity Monitoring’ between 2007 and 2010 (Halls, 2008). This section describes the status and trends of fisheries resources monitored under these two routine programmes during the period 2003 to 2010, hereafter referred to as the AMCF and FEVM fisher catch monitoring programmes, respectively.


The two programmes shared the same principle objective to monitor simple indices of fish abundance, biomass and species diversity through space and time for management and impact assessment evaluation purposes. Both programmes recruited up to three fishers at each monitoring site to record their daily catch by species (weight, number of fish, and maximum fish length) and effort (hours fished by gear type and size) using simple logbooks (Plate 3).


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Plate 3 Fishers in Stung Treng, north-east Cambodia recording information about their landings.

Forty and 23 sites were monitored under the AMCF and FEVM programmes, respectively, representing main river and floodplain habitats (Figure 13 and Figure 14) but landings were also reported from river, canal, lake and reservoir habitats. Ten sites were monitored under both the AMCF and FEVM monitoring programmes (Table 3) over a period of between six or seven years (Table 4). Further details of the survey methods and the results of earlier analyses of collected data are described among others by MRC (2010); Doan et al. (2006) and Halls (2008).

Figure 13 The locations of the AMCF catch monitoring programme (2003-2005).

Fish Abundance and Diversity Monitoring Programmes (Small-Scale Artisanal Fisheries)


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Figure 14 The locations of the FEVM catch monitoring sites (2007-2010).

Table 3 Sites monitored under both the AMCF and FEVM catch monitoring programmes (2003–2010).

Country Province District Village Name HabitatLao Luang Prabang Luang Prabang Ban Pha O Main RiverLao Vientiane Hatxayfong Ban Thamuang Main RiverLao Borikhamxay Paksan Ban Xinh Xay Main RiverCambodia Stung Treng Siem Pang Pres Bang TributaryCambodia Stung Treng Talarborivat Ou Run Main RiverCambodia Ratanakiri Veounsai Banfang TributaryCambodia Ratanakiri Lum Phat Day Lo TributaryCambodia Kra Tie Sambo Koh Khne Main RiverCambodia Kandal Ponhea Leu Sang Var Flood PlainViet Nam An Giang Thoai Son Tay Son Flood Plain

Combined, the two programmes recorded over 450 tonnes of landings (Table 4). The number of species reported annually ranged from 130 to 277 under the AMCF programme, and 117 to 283 under the FEVM programme. River habitat including the Mekong River accounted for most reported landings except in Thailand under the FEVM programme where landings from floodplains were significant. Where data on gear use were available, gillnets caught the majority of the catch, except in Viet Nam where push nets were the main gear type monitored under the AMCF programme. Hooks, traps, liftnets and cast nets were also important gear types. Catch by gear type could not be reliably estimated for the AMCF programme in Lao and Thailand because the database design used by these countries did not accommodate the recording of catches for more than one gear type when several gears were employed by a fisher on a given day. Almost 30 % of catch records for Viet Nam also excluded details of gears used. The databases for both programmes were also found to contain many variants of the major gear and habitat types given in Table 4. For these reasons, the temporal and spatial changes in relative fish abundance and biomass described below are indicated for each monitoring location (village name) simply in terms of catch-per-fisher-per-day. This crude catch-per-unit-of-effort (CPUE) index of relative fish abundance and biomass is also employed for the integrated analyses described in Section 6.



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Table 4 Summary statistics for the catch monitoring programmes.

COMPONENT AMCF FEVMCountry Cambodia Lao Thailand Viet Nam Cambodia Lao Thailand Viet NamFrom 01/04/2003 13/11/2003 07/10/2003 28/06/2003 01/06/2007 01/07/2007 28/05/2007 20/06/2007To 11/12/2005 28/08/2005 14/11/2004 17/12/2005 15/01/2010 20/09/2009 29/07/2009 15/02/2010Years 2.70 1.79 1.11 2.47 2.63 2.22 2.17 2.66Sites 13 6 8 13 6 5 7 5Catch (tonnes) 82.2 29.0 4.8 155.4 43.1 10.5 39.1 99.8Species 180 169 130 277 283 117 199 188Gear 1 Gillnet

(53%)na na Pushnet

(36%)Gillnet (81%)

Gillnet (80%)

Gillnet (31%)

Gillnet (70%)

Gear 2 Liftnet (11%)

na na ns (28%)

Hooks (10%)

Hooks (10%)

Traps (27%)

Trammel net (30%)

Gear 3 Castnet (8%)

na na Frametrawl (19%)

Traps(8%)

Traps(8%)

Hooks (14%)

–

Other 28% na na 17% 1% 2% 28% –Habitat 1 River

(85%)Mekong (97%)

Mekong (62%)

Canal (40%)

River (> 66%)

Mekong (68%)

Floodplain (45%)

River (37%)

Habitat 2 Canal(8%)

– River (26%)

River (29%)

– River (32%)

Mekong (29%)

Ricefield (30%)

Habitat 3 Lake(4%)

– Reservoir (5%)

Mekong (22%)

– – River (27%)

Estuary (29%)

Other 3% 3% 7% 9% na – – –Note: ns – not stated; na – not available.

4.3 Resource status and trends

4.3.1 Species composition

During the course of the two monitoring programmes, 339 species of fish and other aquatic animals(OAA) were reportedly caught by fishers in the four riparian countries (Annex Table 20). Sixty-fourof these species were reported under both programmes in all four countries. Commonly important species in each country measured in terms of their percentage contribution to total catch weight reported under each programme included: Henicorhynchus siamensis, Cosmochilus harmandi, Labeo chrysophekadion, Cirrhinus lobatus, Pangasius conchophilus, Phalacronotus apogon, Puntioplites falcifer, Poropuntius malcolmi, Wallago attu and Barbonymus gonionotus.

Differences in the species composition of landings reported among the four countries and monitoring programmes will reflect natural variation in essential fish habitat availability (resources), and sampling effects including gear use (selectivity), the period over which monitoring occurred each year, sampling (fishing) effort i.e. the number of catch records or number of fish sampled, and variation in local (fisher) and institutional capacity to identify species through space and time.

4.3.2 Trends in species diversity

For the reasons described it is difficult to reliably assess trends in species composition or diversity through space and time based upon the data collected under the two fish catch monitoring programmes. However, in an attempt to provide some baseline for management evaluation or environmental impact assessment purposes, the number of species reported at each site (i.e. species richness) during each month is provided in Annex Table 24. Estimates of species richness, ' S ' at a given locality tend to increase asymptotically or (logarithmically) towards some maximum species richness (Smax) with the number of individuals sampled or with sampling effort (Gotelli and Colwell, 2001; Southwood and Henderson, 2000). Species accumulation curves derived from the cumulative number of species collected/reported, S(n) and measures of sampling effort can be estimated to account (standardize) for differences in sampling effort. Log-linear relationships between S(n) and the loge-transformed number of samples, ln(n) have been used to approximate the species accumulation curve (Palmer, 1991). For small samples, ' S ' tends to be proportional to the number of samples collected (Southwood and Henderson, 2000).

Margalef’s Index (Margalef, 1968) provides a measure of species richness that is approximately normalized for sample size without using the more complex rarefaction techniques described above:

where N is the number of individuals in the sample. This is equivalent to the log-linear model with an intercept (a) = 1 and substituting N for sampling effort or area.

Using data from the AMCF fish catch monitoring programme, Cambodia, it was found that at all 13 locations, fishing days (D) explained more of the variation in ' S ', than ' N ' (Figure 15). Therefore, an alternative species richness index (SRI) was also calculated:

Estimates of N, IMargalef and SRI for each month and sampling site are given in the Annex Table 25 and Table 26, respectively.

Imargalef = S – 1 ,

ln N

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lnD



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Banfang

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Figure 15 An example comparison of the log-linear relationship between monthly estimates of ' S ' and sampling effort measured in terms of ' N ' and fishing days (D) for the Banfang site, Cambodia, monitored under the AMCF programme (2003–2005).

Intra-annual variation

Plotted by month for the 10 sites monitored under both the AMCF and FEVM programmes, the Margalef index and SRI indices exhibited very similar variation through time (Figure 16). A cluster analysis (not shown here) revealed that similarities in monthly variation among sites were a function of their latitude i.e. their relative upstream position to one another. In other words sites close together shared a similar pattern of variation with the dendrogram ordering sites according to latitude. However, general intra-annual patterns were not distinguishable.

Species richness at the riverine sites was lower at the three most upstream sites in Lao PDR compared to those in Cambodia. Species richness was lowest for Tay Son, the floodplain site in Viet Nam but, less variable both inter and intra-annually possibly reflecting a relatively unchanging air-breathing blackfish assemblage seasonally augmented by reophilic migratory whitefish species.

Table 5 Annual trends in estimates of species richness indices.

Site Country Habitat Margalef trend SRI trendBan Pha O Lao PDR Mekong River – Downward**Ban Xinh Xay Lao PDR Mekong River Downward** Downward**Ban Thamuang Lao PDR Mekong River – Downward**Pres Bang Cambodia Sekong River Upward** –Banfang Cambodia Sesan River – –Ou Run Cambodia Mekong River Upward** Upward**Day Lo Cambodia Srepok River – –Koh Khne Cambodia Mekong River – –Sang Var Cambodia Tonle Sap Upward** Upward**Tay Son Viet Nam Floodplain Upward** Upward**

Note: * p < 0.05; ** p < 0.01.

Inter-annual variation

After accounting for monthly variation, ANOVA indicated that estimates of the Margalef index declined with year only at Ban Xinh Xay, increased at Ou Run, Pres Bang, Sang Var and Tay Son, and remained unchanged through time at the remaining four sites (Figure 17 and Table 5). The SRI exhibited a significant downward trend at all three sites in Lao, an upward trend at Ou Run, Sang Var and Tay Son, and no trend at the remaining four sites.



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Figure 16 Intra-annual (monthly) variation in the estimates of the Margalef and SRI species richness indices at sites monitored under both the AMCF and FEVM programmes.

Figure 17 Monthly estimates of the Margalef and SRI species richness indices at sites monitored under both the AMCF and FEVM programmes. Figures are arranged in descending order of latitude.

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4.3.3 Trends in relative fish abundance and biomass indices

Across all 63 sites, monthly estimates of relative fish abundance and biomass indicated by fisher catch rates for the aggregated (multi-species) assemblage ranged from 1 to over 18,000 fish per day (mean = 400/day; S.D.= 1,220/day), and relative biomass from 0.1 to 392 kg/day (mean = 0.32 kg/day; S.D.= 1.1 kg/day), see Annex Table 27 and Table 28.


At the 10 sites monitored under both the AMCF and FEVM monitoring programmes for which the longest time series of observations were available, the trends in relative monthly abundance were broadly similar among the mainstream sites of Ban Pha O, Ban Xinh Xay, Ban Thamuang, Ou Run and Koh khne (Figure 18). At these sites, relative fish abundance (n/fisher/day) typically increased during the early part of the year, peaking between March and May, probably reflecting a surge in fish migrations in the main channel. This was followed by a decline in relative abundance during the high flow period (June–October) when many species of fish move laterally from the main channel to adjacent flood inundated lands (floodplains). Relative abundance increased again during the falling water period (November–February) possibly reflecting return migrations to refuge habitat in the mainstream. These patterns were particularly evident at Ban Pha O and Ban Thamung. Relative biomass, indicated by catch weight per day showed a similar pattern of annual variation that was most pronounced at Ou Run.

At the tributary sites (Pres Bang, Banfang, Day Lo and Sang Var), relative fish abundance showed little seasonal variation except at Sang Var (Tonle Sap) where relative fish abundance (and biomass) peaked around January or February coinciding with the recession of floodwaters from the TS-GL floodplain. This seasonal pattern was also evident in the dai fishery on the Tonle Sap, see (Section 2.4.3). The rise in catch rates (kg/day) at Sang Var during June may reflect a surge of fish migrations towards the Great Lake. The monthly variation in catch rates (kg/fisher/day) at Tay Son is typical of the expected cyclic changes in fish biomass on river floodplains (Welcomme and Hagborg, 1977; Halls et al., 2001) where biomass peaks by the end of the flood (end of September).

Figure 18 Average monthly variation in the indices of fish abundance (left) and biomass (right) at the 10 sites monitored under the AMCF and FEVM programmes (2003–2010).



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Five of the 10 sites showed a significant downward decline in relative fish abundance with time (year), whilst the remaining half showed significant upward or non-significant trends ( Figure 19 and Table 6). Relative fish biomass also showed significant declines at five sites but, upward or non-significant trends at the other five.

Table 6 Annual trend in estimates of relative abundance, biomass and mean body weight.

Site Country Habitat Abundance Biomass Mean weightBan Pha O Lao PDR Mekong River Downward** – Upward**Ban Xinh Xay Lao PDR Mekong River Downward** Downward** –Ban Thamuang Lao PDR Mekong River Downward** Upward** Upward**Pres Bang Cambodia Sekong River Downward** Downward* –Banfang Cambodia Sesan River Upward** Downward** Downward**Ou Run Cambodia Mekong River Upward** Downward** Downward**Day Lo Cambodia Srepok River – – –Koh Khne Cambodia Mekong River Downward** Downward** –Sang Var Cambodia Tonle Sap Upward** – Downward**Tay Son Viet Nam Floodplain Upward** Upward** –

Note: *p < 0.05; **p < 0.01; – no significant trend.

4.3.4 Trends in growth

Among the 63 sites, monthly estimates of mean weight varied from between 0.01 and 31 kg (mean = 0.33 kg; S.D. = 1.1 kg), see (Annex Table 23).


A general seasonal pattern of growth for the multi-species assemblage could not be detected among the 10 sites (Figure 20) or main habitat types. However, strong correlations in the monthly mean weight estimates were found between Koh Khne and Sang Var (r = 0.85) and between Ban Pha O and Ban Thamuang (r = 0.76). At Ou Run, linear increases in loge-transformed estimates of mean weight between May until December were evident each year from 2007 to 2009. This period corresponds to the rising water and floodplain inundation phase of the flood cycle in this part of the basin when growth rates are typically high for most species.


Mean fish weight was found to decline significantly with year at three sites, but, increase or show no significant increase at the remaining seven sites (Table 6). ANOVA revealed that mean weight increased significantly with latitude after accounting for variation in month and year.

Figure 19 Monthly estimates of the relative fish abundance (left) and biomass (right) indicated by loge-transformed average fisher catch rates per day at those sites monitored under both the AMCF and FEVM programmes.



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Figure 20 Average monthly variation in mean fish weight (left) and monthly estimates of mean fish weight (right) at sites monitored under both the AMCF and FEVM programmes.

4.3.5 Abundance, biomass, growth and flooding

The effects of flooding on fish abundance, biomass and growth should become manifest in indices of abundance, biomass and growth by February each year - the month after the end of a typical flood year. At the six sites (all in Cambodia) for which index estimates were available in February for a minimum of four years, only the index of relative biomass of the multi-species assemblage at Sang Var on the Tonle Sap was found to be significantly dependent upon the flood index (p < 0.05), (Figure 21).

4.3.6 Other sites and species-wise analyses

Monthly estimates for the indicators described above for the remaining sites are provided in Annex Table 21 – Table 28. Because of the very large number of possible combinations (> 5000), no attempt was made to examine trends in these indicators by species and site. However, species-wise trends in these indicators are examined in the integrated analyses described in Section 6 for selected species.

4.4 Conclusions

The assessments of trends in the indices of fish diversity, relative fish abundance and biomass, and mean weight through time were all subject to potential bias resulting from temporal and spatial variation in fisher behaviour (e.g. hours fished per day); gear selectivity, (e.g. net mesh size) and efficiency (e.g. net material and construction) and local and institutional capacity to identify species and accurately record landings and fishing effort. The monitoring period was also relatively short, discontinuous, and varied among sites.

Subject to these potential sources of bias, no compelling evidence was found to suggest that indices of species richness, relative abundance and biomass, or mean fish weight had declined among all the sampling locations over the seven year monitoring period. Indices increased at some sites and declined at others. Mean weight was found to be higher at more northerly (upstream) locations consistent with findings reported by Halls et al. (in preparation) for populations of fish caught in the vicinity of deep pools. These workers found that both larger species and larger individuals of the same species were present at higher latitudes possibly reflecting a greater abundance of spawning habitat in upstream locations and the fact that larger species have the capacity to migrate further upstream for refuge and spawning.

It remains uncertain why no consistent trends in relative abundance and biomass were found among sites, particularly those in close proximity to one another. This may be a consequence of bias introduced into the assessment for the reasons given above, or may reflect real local environmental and/or fishing effects on stocks. It is also important to bear in mind that given the inherent variability in the abundance and biomass of fish stocks in the LMB exemplified in the longer time series of equivalent indices for the Cambodian dai fishery, detecting significant trends in indices of this type



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will likely require many years of observations. For example, had the dai fishery been monitored only since 2004, there would be a high risk of committing a Type I error (i.e. falsely rejecting the null hypothesis when it is true) when testing for a significant trend in catch rates.

Upward trends in the richness indices may reflect a growth in the capacity of local fishers and supporting research agencies to identify species including the continuous development of species identification catalogues. The apparent declines in richness at the Lao sites were observed over fewer estimates than the other sites and may simply reflect the effects of natural variation, rather than longer-term sustained declines. For more robust trend assessments, species diversity indices such as the Shannon-Weiner Index, 'H ' (with 95% CI) could be compared among or between sites of interest by month where similar sampling effort (fishing days) with a common gear type (e.g. gillnet) is observed, and by treating the monthly catch rates of individual fishers at each site as sample replicates. This would avoid potential bias resulting from the effects of seasonal migration, gear selectivity and variation in sampling effort.

Except for the index of relative biomass at Sang Var on the Tonle Sap, any flood effects on the multispecies assemblage beyond this location were undetectable. As discussed further in Section 6.3.5, this may reflect the precision of the index estimates and the lack of contrast (low variance) in the flood index observations. Alternatively, fish stocks exploited at sites beyond Sang Var may not utilise the TS-GL system for feeding. Evidence of fish migrations between the TS-GL system and the fisher catch monitoring sites is examined in Section 6.

Figure 21 Estimates of indices of average fish abundance, biomass and mean weight in February each year,

plotted as a function of the flood index for the six sites in Cambodia.


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5 Larvae Density Monitoring Programme

5.1 Introduction

Many fish species in the Mekong River are believed to migrate upstream to spawn (Poulsen et al., 2004; Baird et al., 2003). The spawned eggs and larvae then drift back to populate the river and floodplains downstream. These upstream migrations may help to counter the downstream drift of young life stages or enhance dispersal over a range of suitable downstream habitat, as well as improve the survival rates of developing progeny (Lucas and Baras, 2001; Welcomme, 1985).

The density of larvae in the drift provides an index of the reproductive success and the likely levels of recruitment of young fish to stocks each year. In populations of fish with high natural mortality rates comprising few age groups (cohorts) typical of many of the small species of cyprinid that dominate landings in the LMB, annual recruitment of fish will also have a significant influence on fish yields each year.

Predicting recruitment is notoriously difficult since it is driven by a combination of the size of the spawning stock, spawning success and larvale survival. Spawning success and larvale survival may be influenced by a host of environmental factors including hydrological conditions, food availability and predator density. Monitoring the density of fish larvae density therefore provides an effective means of predicting yields from fish populations comprising few cohorts.


In Cambodia, the Fisheries Administration (FiA) has been monitoring the density of fish larvae in the Mekong and Tonle Sap rivers since 2002 with technical and financial support from the MRC. Both larval sampling sites are located in Phnom Penh around the Chaktomuk area in Chrouy Changvar district (Figure 22).


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Figure 22 The location of the fish larvae density monitoring sites in Cambodia and Viet Nam

A standardised methodology has been employed to monitor relative larvae density each year based upon repeated 30 minutes sampling every six hours using a 1 m diameter bongo-net with a 1 mm mesh size, set 2 m from the surface of the river and 20–30 m from the river bank. The bongo net is equipped with a flow meter to measure the volume of filtered water. Larvae are removed from the cod-end of the net and preserved in formalin and subsequently identified to the lowest taxonomic level. Further details of the sampling and larvae density estimation methodology are described by Tharith et al. (2003).

In Viet Nam, the Research Institute for Aquaculture II (RIA2) has been monitoring fish larvae in the Mekong and Bassac rivers since 1999 with technical and financial support from the MRC. The two sites, both located in An Giang province close to the Cambodian border, are at Vinh Xuong on the Mekong River and at Quoc Thai on the Bassac River (Figure 22). Bagnets and later bongo nets were used to sample the ichthyoplankton for 2–3 hours during low water, twice per day. However, valid comparisons and interpretations of larval density estimates have been made difficult because different sampling periods and locations have been selected for monitoring in most years. Furthermore, at the time of publication, comprehensive error checking of the database was required because the structural integrity of the database was compromised when defined relationships between table fields were removed during software upgrades. Therefore only data for Cambodia are examined below.

5.3 Status and trends

5.3.1 Species Composition

At both sites, larvae belonging to the Henicorhynchus genus were found to be most abundant and dominate the larvale composition (Figure 23). Samples from the Tonle Sap contained a much more diverse larvae fauna where Esomus longimanus, Ichthyocampus carce, and Gobiopterus chuno and Krytopterus species were also relatively abundant. At the Mekong site, larvae of the Pangasius genus were also abundant.

Larvae Density Monitoring Programme


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Figure 23 Species composition of larvae samples taken from the Tonle Sap (above) and Mekong River (below) sampling sites 2002–2009.

Proportions represent average daily density between June and September averaged across all sampling years.

Corica laciniata

Cyclocheilichthys lagleri

Esomus longimanus

Gobiopterus chuno

Henicorhynchus siamensis

Henicorhynchus spp.

Ichthyocampus carce

Kryptopterus bicirrhis

Kryptopterus geminus

Kryptopterus schilbeides

Labiobarbus leptocheila

Other

Pangasius elongatus


Parambassis apogonoides

Puntius binotatus

Rasbora dusonensis

Rasbora myersi

Rasbora spilocerca

Species

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Cirrhinus caudimaculatus

Clupeoides borneensis

Corica laciniata


Henicorhynchus spp.

Ichthyocampus carce

Other

Pangasianodon hypophthalmus

Pangasius bocourti


Pangasius larnaudii

Pangasius macronema

Pangasius pangasius

Pangasius sp. 1

Pangasius sp. 2

Parambassis siamensis

Puntius orphoides

Sundasalanx mekongensis

The number of species reported in samples each year varied from 22 (2003) to 12,099 (2005) at the Tonle Sap site and from 83 (2003) to 130 (2004) at the Mekong site. However, the number of species recorded in samples each year was found to be strongly influenced by sampling effort (Figure 24) typical of an asymptotic species accumulation curve (Southwood and Henderson, 2000). No significant changes in the number of species identified in the samples were detected through time (p > 0.05) at either sampling location when the variation in the sampling effort (days) was accounted for, and after excluding years with fewer than 50 sampling days between June and September (2003 at

Figure 24 The number of species identified in larvae samples taken between June and September each year plotted as a function of the number of sampling days during the same period.

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both sites and also 2002 at the Mekong site). The number of species sampled per day was found to be marginally higher for the Tonle Sap (1.05 species/sampling day), compared to 0.85 for the Mekong (p = 0.02).

5.3.2 Trends (all species)

Larvae sampling periods and total sampling days varied between 2002 and 2009 (Figure 25). Sampling effort was intense during 2004, 2005 and 2008, but, few samples were taken during 2003. Typically the highest larvae densities were found between June and September each year corresponding to the period when waters flow in to the Tonle Sap towards the Great Lake. Sampling intensity was typically also high during this period and occurred daily during this period in 2008.



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Figure 25 Daily estimates of mean larvae density in the Tonle Sap and Mekong River, Cambodia, 2002–2009. Broken horizontal reference line at 1 larvae m-3 included to aid comparisons. Note loge scaling: Loge-transformed daily larvae density estimates for the Tonle Sap and Mekong River sampling locations

are significantly (p < 0.001) but weakly (r = 0.19) correlated.

Figure 26 Estimates of mean loge-transformed daily larvae density between June and September for the Mekong River (upper) and Tonle Sap (lower), 2002–2009.

Error bars give 95% confidence intervals around the mean.

Estimated means of the natural logarithms of daily larvae density between June and September have exhibited high inter-annual variation since the start of the monitoring programme (Figure 26). Geometric mean daily larvae densities were highest in 2004 and 2005 and lowest in 2003 and 2002 at the Mekong and Tonle Sap sampling sites respectively. Densities in 2008 were also relatively high.

Arithmetic mean daily larvae density was highest in 2004 at both sampling locations (Table 7 and Figure 27), suggesting that the arithmetic mean density estimate for the Tonle Sap site during 2004 was influenced by a few very high density observations. Arithmetic mean densities at the two locations are highly correlated (r = 0.93, p < 0.01).



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Table 7 Estimates of geometric (GM) and arithmetic (AM) mean daily larvae density at the Mekong and Tonle Sap sampling locations, Cambodia, between June and September, 2002–2009.

DAILY DENSITY (larvae/m3)*1000Mekong River Tonle Sap

Year n GM AM n GM AM2002 25 143 3,782 64 109 3912003 41 48 106 7 5,167 38,6372004 120 469 27,533 75 7,044 78,6572005 120 166 8,200 109 10,405 51,0792006 117 138 911 67 2,592 14,9512007 121 101 1,767 113 1,300 3,0422008 121 181 3,172 122 9,321 23,1182009 107 82 349 52 550 4,372

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Figure 27 Estimates of arithmetic mean daily larvae density (June–September), 2002 – 2009, all species.

5.3.3 Trends by species

Larvae densities sampled at the Tonle Sap peaked in 2005 for 15 out of the 18 species that have consistently exhibited high densities in the ichthyoplankton drift including Henicorhynchus siamensis (Figure 28). However, the density of larvae of other Henicorhynchus species, the most abundant species in the drift, peaked in 2004 and to a lesser extent in 2008. The density of larvae of several other species also showed a lesser peak during 2008. At the Mekong river sampling site, a similar pattern to that for the Tonle Sap was observed for Henicorhynchus siamensis and Henicorhynchus species although densities peaked during different years for the remaining four most abundant species identified in the drift (Figure 29).

Figure 28 Mean daily larvae density estimates (x 1000) between June and September, 2004–2009 for the Tonle Sap sampling site. Only those species with 5 or more observations and comprising more than 1% of the average larvae density between 2002 and 2009 are shown.

Reference line at 2005.



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Figure 29 Mean daily larvae density estimates (x 1000) between June and September, 2004–2009 for the Mekong River sampling site. Only those species with 5 or more observations and comprising more than 1% of the average larvae density between 2002 and 2009 are shown.

Reference line at 2005.

Figure 30

Frequency of peak larvae density by year for species recorded in samples from the Tonle Sap (upper figure) and Mekong River (lower figure) monitoring sites. Only those species recorded in at least five years between 2004 and 2009 are included.

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At the Tonle Sap sampling site, larvae density peaked in 2005 for more than 50% of the species recorded during at least five different years between June and September 2004 to 2009 (Figure 30). However, at the Mekong sampling location, larvae densities were found to peak during 2008 for almost 45 % of the species present in samples.

Densities peaked at both locations during 2005 for only four species and during 2008 for only 3 species (Table 8).

Table 8 Species exhibiting peaks in their larvae density estimates at the Mekong (MK) and Tonle Sap (TS) sampling locations in 2005 and 2008.

2005 2008Species name MK TS MK TSAcanthopsoides gracilentus +Acantopsis sp.1 + +Achiroides melanorhynchus +Amblyrhynchichthys micracanthus +Barbonymus altus +Barbonymus gonionotus +Chitala lopis +Cirrhinus microlepis + +Clupeichthys aesarnensis + +Clupeoides borneensis + +Corica laciniata + +Crossocheilus reticulatus + +Cyclocheilichthys furcatus +Cyclocheilichthys repasson +Cynoglossus feldmanni +Helicophagus leptorhynchus +Hemibagrus nemurus +Henicorhynchus siamensis + +Homaloptera zollingeri +Kryptopterus bicirrhis +Labeo chrysophekadion + +Labeo dyocheilus +Labiobarbus leptocheila +Labiobarbus siamensis + +Lobocheilos davisi +Mastacembelus armatus +Nemacheilus longistriatus + +Notopterus notopterus + +Ompok eugeneiatus + +Osteochilus melanopleurus +Osteochilus microcephalus + +Oxygaster pointoni + +Pangasianodon hypophthalmus +Pangasius bocourti + +Pangasius conchophilus +Pangasius elongatus +Pangasius macronema + +Pangasius pleurotaenia +



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Species name MK TS MK TSPangasius sp.1 + +Paralaubuca typus +Parambassis siamensis +Parambassis wolffii +Poropuntius malcolmi +Puntioplites proctozystron + +Rasbora dusonensis +Sikukia gudgeri +Syncrossus helodes + +Wallago attu + +Yasuhikotakia modesta +Yasuhikotakia morleti + +

At the Tonle Sap site, species that exhibited peak densities in 2005 predominantly belong to the Cyprinidae family, are typically small in size, and more than half are omnivorous (Table 9). In contrast, more than half of the species exhibiting peak densities in 2008 belong to the Pangasiidae family with medium, large or giant body lengths and almost half are carnivores. At the Mekong sampling site, species exhibiting peak densities in 2005 belong largely to the Clupeidae and Pangasiidae families, but, most are small omnivorous species. Peak larvae densities in 2008 were common for small carnivorous cyprinids and loaches (Cobitidae). However, no significant (p < 0.05) differences were detected between the maximum length of species exhibiting peak larvae densities in 2005 and those in 2008 at either sampling location.

Table 9 Characteristics of species exhibiting peak larvae densities in 2005 and 2008 at the Tonle Sap and Mekong River sampling locations.

TONLE SAP MEKONG RIVERFamily 2005 2008 2005 2008Ambassidae 1 1Bagridae 1Balitoridae 1 2Clupeidae 2 1 3 Cobitidae 3 3Cynoglossidae 1 Cyprinidae 13 2 2 11Mastacembelidae 1 Notopteridae 1 1 1Pangasiidae 3 7 3 1Siluridae 1 2Soleidae 1

Total 25 13 9 22

Size Category 2005 2008 2005 2008Giant 3 2 3Large 3 2 1 3Medium 4 6 3 2Small 15 3 5 14Total 25 13 9 22

Feeding Guild 2005 2008 2005 2008Carnivorous 8 6 2 11Herbivorous 3 1 1 4Omnivorous 14 6 6 7Total 25 13 9 22

5.4 Origin of ichthyoplankton drift

Among samples taken from the Mekong site in June, 2009, the estimated mean length of larvae of Henicorhynchus species was estimated to be 4 mm equivalent to a 7-day-old larvae, and 6–14 mm for Pangasius species, equivalent to 13-day-old larvae (Tharith pers comm.). If these larvae drifted passively with the flow at an average rate of 0.55 ms-1, then larvae of Henicorhynchus and Pangasius species could have drifted between approximately 300 km and 600 km respectively from upstream locations, which would include the Khone Falls area. However, it should be borne in mind that these distances are likely to be maximum since larvae may actively swim whilst in the drift and may be exposed to lower flows when near the banks or the bed of the river.

5.5 Summary and conclusions

In Cambodia, the density of fish larvae in the Mekong and Tonle Sap rivers has been monitored since 2002. Larvae density in the drift has also been monitored in Viet Nam in the Mekong and Bassac rivers since 1999 but concerns over the reliability of these data prevented their use here. Larvae sampled at these locations may have drifted over hundreds of kilometres from upstream locations.

At both the Mekong and Tonle Sap sampling locations in Cambodia, larvae belonging to the Henicorhynchus genus were found to be, on average, most numerically dominant in the drift. At the Mekong site, species belonging to the Pangasius genus were also abundant but, at the Tonle Sap site, these species were less abundant. Samples from the Tonle Sap contained relatively high abundances of several small and commercially unimportant species of barbs, pipefish and the gobies (e.g. Esomus longimanus, Ichthyocampus carce and Gobiopterus chuno). These species are often sedentary or occupy slow flowing waters (Froese and Pauly, 2010). Therefore, their larvae may be of a local origin. Differences in species composition between the two sites therefore probably reflect the transport of



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the larvae of highly migratory riverine species from the Mekong mainstream to the Tonle Sap where locally-spawned larvae of sedentary species are relatively abundant.

Average species richness each year was found to be marginally higher at the Mekong sampling site (91 species) compared to the Tonle Sap (80 species), but no significant trends in the number of species identified in the samples were detected through time at either sampling location after accounting for differences in sampling effort.

After 2003, when sampling occurred almost daily between June and September, the estimated arithmetic mean daily larvae density (all species combined) was highest in 2004 at both locations due mainly to significant densities of larvae from Henicorhynchus species. Densities of all species combined remained relatively high in 2005 at both sites. In 2005, contributions from Henicorhynchus species and H. siamensis to densities at the Tonle Sap site appeared modest, but, relatively large contributions were made by other species including those belonging to the Pangasius genus. At the Mekong site in 2005, densities of larvae belonging to I species and H. siamensis were significant. These species also contributed significantly to the larvae density observed at both sites in 2008.

Moreover, whilst contributions from Henicorhynchus species and H. siamensis tended to dominate inter-annual variation in larvae density for all species combined at both sites, the density of larvae belonging to other species at the Mekong site peaked most frequently in 2008. At the Tonle Sap site, the density of larvae belonging to other species peaked most frequently in 2005 but, also at a high frequency in 2008.

Assuming that larvae of migratory species found in the Tonle Sap were transported from the Mekong, as indicated by the strong correlation found between arithmetic mean daily larvae densities at the two sites, a similar pattern of variation in the frequency of peak densities might be expected between the two sites. Excluding data for 2005, the frequency of peak density at the two sites was found to be significantly correlated (r = 0.93, p < 0.05) supporting this assumption. Transport of larvae from the Mekong to the Tonle Sap in 2005 may have been high for many species as a result of particular hydrological conditions. Inflow (m-3/s-1) into the TS-GL system peaked in 2005, as did the rate at which the flood rose – the flood rise rate (FRR) (Figure 31). Furthermore, for those species present in samples each year between 2004 and 2009, larvae density in the Tonle Sap was found to be significantly dependent upon inflow rates (Table 10). Whilst larvae density estimated at the both sites account for flow (the volume of water sampled), larvae may become more concentrated in the Tonle Sap with higher inflows or may become more vulnerable to the sampling gear.

Table 10 ANOVA results to test the dependence of loge-transformed larvae density (LNTS) in the Tonle Sap on inflowing volume of water (Q) accounting for differences among species (SP).

TESTS OF BETWEEN-SUBJECTS EFFECTSSource Type III Sum of Squares df Mean Square F Sig.Corrected Model 264.977a 24 11.041 2.340 .001Intercept 5.918 1 5.918 1.254 .265Q 80.072 1 80.072 16.970 .000SP 183.126 23 7.962 1.687 .038Error 552.070 117 4.719Total 4998.891 142Corrected Total 817.047 141

Dependent Variable: LNTS

a. R Squared = .324 (Adjusted ' R ' Squared = .186)

The high frequency of peak larvae densities in the Mekong and Tonle Sap in 2008 may also be linked in some way to hydrology. It is noteworthy that flooding in 2008, when water levels exceed their mean, began relatively early (20/07/2008) and was also relatively long compared to the previous four years (Figure 31). These conditions may have been favourable for spawning giving rise to high average larvae density for many species.

Whilst the density of larvae for Henicorhynchus species and H. siamensis was also relatively high in 2008, it was exceptionally high in the Mekong in 2004 and remained high in 2005. An exceptionally high density of larvae of these species was also found at the Tonle Sap sampling site in 2004, but, the density was disproportionally lower in 2005 compared to that observed in the Mekong.

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Hydrology-related explanations for these exceptionally high densities are unlikely because conditions in 2004 were unremarkable except that the maximum water level for that year ranked third after 2005 and 2009 for the period 2004 to 2009 (Figure 32).

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Figure 32 Annual maximum water level at Pakse, Lao PDR and Kompong Luong in the Tonle Sap, Cambodia.

Figure 33 The generalized life-cycle and migration model for important whitefish species in the LMB.

6 Integrated analyses

6.1 Introduction

This section draws upon the data from all four monitoring programmes to explore further the dynamics of important migratory whitefish species in the LMB. The explorations are based upon a generalized life-cycle and migration model (Figure 33) reported to be applicable to many important riverine fish species (Poulsen et al., 2004; Baird et al., 2003). As water levels on floodplains including the TS-GL system begin to fall, typically by mid–October, fish begin to migrate to refuge habitat including deep pools in the main channel. These migrations peak in January when catch rates in the dai fishery reach a maximum during the fishing season (October–March). As water levels begin to rise again in April, fish begin upstream migrations to spawning habitat in the main channel and tributaries. The lee trap fishery targets these upstream spawning migrations. Spawning typically occurs in June or July corresponding to the time of flow reversal in the Tonle Sap and the start of floodplain inundation. Larvae and adults return (often drifting passively with the flow) to colonise downstream floodplain habitat where they feed and grow until water levels begin to fall again in October. Drifting larvae are sampled by the larvae monitoring programme between June and September. Other species may remain resident in the main channel or on the floodplain throughout the year, or may exhibit similar migratory behaviour but, over smaller distances. Other generalist species may adopt more opportunistic behaviour according to the prevailing conditions.


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6.2 Methodology

To examine the validity of the generalized life-cycle and migration model and to build improved understanding of the dynamics of fish stocks in the basin, the following were examined for selected species:

6.2.1 The timing and extent of fish migrations

Estimates of relative fish biomass indicated by mean daily fisher catch rates (kg/day) during each month were plotted as time series for each of the 10 sites monitored under both the AMCF and FEVM fisher catch monitoring programmes. The plots were then examined for patterns and trends through space and time to indicate the probable extent of migrations and thereby geographic range of the species. Peaks in catch rates trends were assumed to correspond to migrations of fish. For each species, the Pearson correlation coefficient was estimated for each pair of sites. Catch rates were loge-transformed to meet normality assumptions.

6.2.2 Spawning locations

Attempts were made to identify upstream sources of fish larvae sampled at Phnom Penh and thereby important spawning locations in the basin assuming that the density of larval fish increases as a linear function of the biomass of their spawning stock.

For the selected species, regression analysis was used to test the functional (linear) dependence of annual estimates of mean larvae density sampled at both the Mekong River and Tonle Sap (June–September) on mean spawning stock size indicated by estimates of the mean daily catch rates of fishers at their catch monitoring locations during the spawning season (April–September); and (ii) mean daily lee trap catch rates estimated during June each year. Estimates of mean larvae density were loge-transformed to meet normality assumptions. Larvae density estimates for 2002 and 2003 were excluded for the reasons described in Section 5.3.2.

Functional dependence would suggest that the larvae sampled from the drift are likely to have been spawned from fish at or above the upstream catch monitoring location. Strong dependence measured in terms of the coefficient of determination (R2) might indicate that the site is a particularly important spawning location. The results of the analysis were also used to help to determine the extent of fish migrations from the larvae monitoring location.

Because of incomplete survey coverage, indices of spawning stock size for Tay Son and Ban Xinh Xay fisher catch monitoring sites exclude observations for September 2004 and 2005, respectively. Estimates of relative spawning stock size at all ten fisher catch monitoring sites also exclude observations for April and May 2007. The results for these locations should therefore be treated with caution.

Because it often difficult to identify fish species at their larval stage, misidentification is likely to be common and it is often only possible to identify individuals to the genus level. Such groupings may therefore include several species belonging to the genus. For example the category, Henicorhynchus spp. used by the larvae density monitoring survey is likely to contain individuals of both Cirrhinus lobatus and Henicorhynchus siamensis. Therefore additional relationships were examined to account for these groupings and likely misidentifications.

6.2.3 Recruitment effects on stocks migrating from the TS-GL

The abundance or biomass of fish migrating from the TS-GL system during the flood recession (October–March) to dry season refuge habitat each year was hypothesized to be functionally dependent upon recruitment to the stock during the earlier flooding phase (June–September).

The number of fish larvae transported within the drift to the TS-GL system or to other downstream destinations between June and September provides a measure of relative recruitment strength each year or recruitment index (RI). The recruitment index in year ' y ' (RIy) is estimated as product of the mean daily larvae density, the estimated mean daily flow rate, Q, and the number of days in the period (122):

where δi is the larvae density estimate (larvae m-3) on day ' i ', and Qi is the flow (m-3 day-1) on day ' i '.

These estimates are relative rather than absolute measures of total transport because larvae densities are typically higher at depth than at the sampled surface waters (Hortle et al., 2005).

Regression analysis was used to test for the linear dependence of stock abundance and biomass for the multi-species assemblage, and for selected species, indicated by their catch rates in the dai fishery, on their recruitment index. Dai fishery catch rates were first loge-transformed to meet normality assumptions.

6.2.4 Extent of fish migrations from the TS-GL

For selected species, regression analysis was used to test the (linear) dependence of estimates of their relative spawning stock abundance and biomass at the fisher catch and lee trap monitoring sites on their respective abundance and biomass indices estimated for the dai fishery.

At the fisher catch and lee trap monitoring sites, relative stock size was indicated by average daily catch rates between April and September. At the dai fishery, this was indicated by average catch rates during the preceding dai fishing season (October to March). Catch rates at the 10 fisher catch and lee trap monitoring sites were first loge-transformed to meet normality assumptions. Linear dependence

30Sept 30Sept

∑δi ∑Qi RIy= i = 01June . i = 01June .122

n n

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was interpreted as indicating that the species at the location migrate from the TS-GL system.

As already described above, indices of spawning stock size for Tay Son and Ban Xinh Xay exclude observations for September 2004 and 2005, respectively. Estimates of relative spawning stock size at all ten fisher catch monitoring sites also excluded observations for April and May 2007. The results should therefore be also treated with caution.

6.2.5 Extent of flood effects on fish growth

The effect of flood extent and duration on fish growth in the TS-GL system was illustrated for the multispecies assemblage caught by the dai fishery as it migrated to refuge habitat during the flood recession (Section 2.5). Assuming that this is a localized effect, the geographic extent over which these flood effects are manifest in the growth (body weight) of fish sampled at other locations in the basin following the flood recession might indicate the migratory range of species. Regardless of its interpretation with respect to fish migrations, evidence of these flood effects on fish growth in other parts of the basin would have important implications for development activities in the basin that may modify flooding patterns.

For each selected species at the 10 fisher catch monitoring sites, regression analysis was used to test the linear dependence of their mean body weight in February each year (shortly after the flood recession in the TS-GL system) on the extent and duration of flooding in the TS-GL system indicated by the flood index. Estimates of mean weight were loge-transformed to meet normality assumptions.

Chi-square tests were used to test the null hypothesis that the frequency of positive and negative linear dependencies for the species-site combinations was equal, and where applicable, also equal across species and sites.

6.2.6 Management effects

As described in Section 2.6, workers have suggested that gear confiscations made in the TS-GL system may have contributed to the very high catch rates observed in the dai fishery in 2004–05 and particularly during 2005–06 by reducing rates of exploitation and thereby improving recruitment and yield-recruit.

Gear confiscations would be judged to be effective if rates of exploitation declined in response to the confiscations. Whilst there are no estimates of fishing mortality to examine this response, mean fish size may be used as a proxy. If gear confiscations are effective, an increase in mean fish weight might be expected as more fish could grow to a larger size before being captured. Catch rates in the dai fishery would also be expected to increase.

A general linear model (GLM) was used to test the linear dependence of mean fish weight in year ' y ' on the quantity of each gear confiscated in the same year, after accounting for the covariation

in the flood index – a variable known to affect fish growth in the TS-GL system, see (Section 2.5).

The linear dependence of dai catch rates (n/dai/season) in split year y/y+1 on the quantity of each gear confiscated in year ' y ' was also tested after accounting for the covariation in larval transport to the system each year ' y ' indicated by the arithmetic mean daily larvae density-based recruitment index, RIy. Given that most of the dai catch is landed in January or December, it was assumed that the effects of gear confiscations during year ' y ' would be detectable in the dai catch rates estimated for the split year y/y+1.

6.2.7 Selected species

Because the species reported under the monitoring programmes are numerous, it would be impractical to examine the correlations and functional dependencies described in Section 6.2.1– 6.2.5 for each. Instead, 12 species were selected for the assessments (Table 11) as follows. Species landed in the dai fishery were first ranked in descending order of their average percentage contribution to the catch each season (1997 – 2010). Those (30) species comprising on average, 95% of the catch each season were then selected. Species not also reported by the fisher catch monitoring programmes or the larvae monitoring programme were removed. Twelve species were then selected from those remaining based upon their ranked average contribution to the annual catch at the fisher catch monitoring sites and their presence at the lee trap fishery. When two or more species belonging to the same family and size category and sharing similar diet preferences were identified, the least abundant species were dropped (e.g. Yasuhikotakia modesta was selected in preference to Syncrossus helodes). This somewhat judicious selection process aimed to include the most abundant species reported by at least three of the four monitoring programmes whilst also ensuring that a range of different families of fish of different sizes and diet preferences were included.

Table 11 The species selected for the correlation/function analysis.

MONITORING PROGRAMME RANKING

Species name Diet Size cat-egory

Max. length (cm)

Dai Fishery

FCM Lee Trap

Larvae Tonle Sap

Larvae Mekong

Cirrhinus lobatus Herbivorous Small 20 1 5 5 8 1Henicorhynchus siamensis Herbivorous Small 20 4 1 5 15 4Labeo chrysophekadion Herbivorous Large 90 6 4 – 41 45Puntioplites proctozystron Omnivorous Small 30 8 28 – 21 40Cirrhinus microlepis Omnivorous Large 70 10 61 – 40 32Poropuntius malcolmi Omnivorous Medium 50 25 11 – 36 53Cosmochilus harmandi Omnivorous Giant 100 28 3 – 57 51Yasuhikotakia modesta Carnivorous Small 30 14 60 – 25 47Pangasius pleurotaenia Omnivorous Medium 40 15 75 3 11 18Pangasius larnaudii Omnivorous Giant 150 13 74 2 65 11Pangasius conchophilus Omnivorous Giant 120 30 7 1 56 13Hemibagrus nemurus Omnivorous Large 80 29 8 8 74 83

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6.3 Results

6.3.1 Fish migrations

Small cyprinids

Cirrhinus lobatus and H. siamensis show similar patterns of both inter and intra-annual variation in relative biomass (Figure 34). Biomass tends to peak in January each year at Sang Var on the Tonle Sap and one or two months later at Tay Son (for H. siamensis) perhaps indicating the migration time between these locations. Peaks are also evident each year at sites upstream of Sang Var in April or May, as far as Pres Bang (Sekong Tributary). These may reflect upstream spawning migrations to locations in these areas. Twenty-one significant correlations in monthly catch rates between monitoring sites were found for these two species (Annex Table 29). Monthly catch rates for H. siamensis were significantly correlated among sites from Sang Var to Ou Run and between Ou Run and Ban Thamuang (p < 0.05) possibly reflecting two discrete stocks above and below Ou Run close to the Khone Falls. For C. lobatus, significant correlations spanned more sites with less evidence of clusters of correlations above and below Ou Run perhaps more indicative of a single migratory population.

These two species also appear to exhibit similar patterns of migratory behaviour which are consistent with the migration and lifecycle model described above. Around the time of spawning, these species are particularly abundant in the mainstream at Ou Run and Koh Khne, and at the three tributaries sites in the Sesan basin: Pres Bang (Sekong River), Banfang (Sesan River); and Day Lo (Srepok River), suggesting that these are important spawning locations. Day Lo (Srepok River) appears to be the least important site, particularly in recent years. There is also some evidence that relative biomass of these two species has declined through time, particularly at Pres Bang. Furthermore, few fish appear to be caught upstream of the Khone Falls since June 2005.

Puntioplites proctozystron shows a much less predictable pattern of seasonal variation in relative biomass among the monitoring locations (Figure 35). These patterns show little similarity with those of C. lobatus and H. siamensis.

Monthly catch rates for P. proctozystron were significantly correlated between seven pairs of sites mostly clustered between Koh Khne and Banfang possibly indicating a relatively large but discrete population in this vicinity, with separate populations located upstream and downstream (Annex Table 29).

Judging by the absence of predictable patterns of abundance through space and time, Puntioplites proctozystron may undertake shorter migrations and have a more flexible reproductive behaviour. Relative biomass has shown considerable declines at most sites and particularly at the tributary sites (Pres Bang, Banfang, and Day Lo).

Medium and large cyprinids

Patterns of variation in relative biomass for Labeo chrysophekadion are also difficult to identify (Figure 35) although peaks in biomass are often evident around December and June–July probably associated with refuge and spawning migrations consistent with the generalised life cycle model described above. This species appears to be particularly abundant in the mainstream between the Tonle Sap and Ou Run (Stung Treng), in the Srepok River (Day Lo) as well as in central and northern Lao PDR (Ban Xinh Xay and Ban Pha O). It appears to be much less abundant in the Sesan and Sekong rivers. Monthly catch rates were significantly correlated among sites between Koh Khne and Ou Run, and between sites in this region and Ban Xinh Xay (Annex Table 29).

Generalisations about the pattern of variation in the relative biomass index for Cirrhinus microlepis were made difficult by the few observations available (Figure 36). Peaks in catch rates were evident in December or January each year but, peaks during other months were less regular. Significant correlations in monthly catch rates were found between Ban Xinh Xay and Day Lo, Koh Khne and Sang Var, as well as between Koh Khne and Sang Var and Ou Run and Banfang (Annex Table 29). There were few catches of this species beyond the Cambodian borders. There was no strong evidence to reject the applicability of the generalized life-cycle model.

Poropuntius malcolmi appears not to inhabit the Tonle Sap or floodplains at Tay Son but, is abundant upstream from at least Koh Khne (Figure 36). It was particularly abundant in the Srepok River where catch rates peak between September and November as waters recede from floodplains. Regular peaks between these events that might be indicative of spawning migrations were not readily identified. There was no obvious long-term trend in catch rates at any of the monitoring sites. Monthly catch rates were significantly correlated between six pairs of sites, most strongly between Ban Pha O and Ban Thamung (Annex Table 29). This species may migrate from the main channel to spawn in tributaries and floodplains in the Sesan basin before migrating back to dry season refuge habitat in the tributaries and the main channel.

Cosmochilus harmandi exhibited a similar pattern of variation in catch rates to L. chrysophekadion (Figure 37). This species appears to be particularly abundant in the mainstream at Ou Run and Koh Khne, and also in the Srepok River (Day Lo). Also like L. chrysophekadion it appears to be much less common in the Sesan and Sekong rivers. It is also abundant in central and northern Lao PDR at Ban Xinh Xay and Ban Pha O around August and September. Monthly catch rates were significantly correlated between seven pairs of sites located between Koh Khne and Ban Pha O (Annex Table 29). There was no obvious evidence of long-term declines in catch rates at the monitoring locations.

Loaches

Yasuhikotakia modesta is caught in almost every month at Sang Var (Tonle Sap) with peak catch rates observed from October to February December (Figure 37). Upstream, at Koh Khne and in the Sesan river basin tributaries, catch rates tend to peak in April or May. These patterns are similar to those of

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C. lobatus and H. siamensis and consistent with the generalized life-cycle model. Again, there are no obvious long-term trends in catch rates at the monitoring locations. Correlations in catch rates were significant but weak for four pairs of sites, including between Day Lo and Koh Khne and between Day Lo and Banfang (Annex Table 29).

Bagrid and Pangasiid catfish

Catch rates for Pangasius pleurotaenia in the Tonle Sap (Sang Var) peaked in August in most years (Figure 38). Upstream, catch rates tended to peak in either December or January, and between July and August. This species may therefore be entering tributaries and floodplains to prey on young fish and other food resources during the flood period, returning to dry season refuge habitat in the main channel at the end of the flood. No significant correlations in catch rates were found between sites (Annex Table 29). Only at Sang Var was there any evidence of a long-term decline in catch rates.

Pangasius larnaudii and P. conchophilus showed some similar patterns of variation in their catch rates (Figure 38 and Figure 39). Like P. pleurotaenia, catch rates for both species peaked in the Tonle Sap (Sang Var) in August as well as between December and January suggesting that they enter and exit the TS-GL system during these periods. Upstream, catch rates for P. conchophilus also peaked between April and May - this was particularly evident at Ban Xinh Xay but, also peaked between December and January in Cambodia. This species may therefore undertake spawning migrations from the main channel in Cambodia from April arriving at upstream spawning sites in northern Lao PDR in May. Adults and juveniles may then return downstream to floodplain habitat in Cambodia to feed on young fish and molluscs in August. Refuge migrations to the main channel are likely to occur between December and January as waters recede from the floodplains. Catch rates for P. larnaudii upstream of Sang Var also peaked in April at some sites but, overall patterns of variation are less consistent than for P. conchophilus. Furthermore, unlike P. conchophilus, P. larnaudii appeared to be virtually absent in landings in Lao PDR.

Catch rates for P. conchophilus showed no obvious decline during the monitoring period. For P. larnaudii, declines in catch rates were apparent at Banfang, Ou Run and Day Lo.

Hemibagrus nemurus was not reported in Cambodia or Viet Nam (Figure 39). In Luang Prabang (Ban Pha O), catch rates showed pronounced peaks between May and July possible representing spawning migrations. Catch rates at Ban Xinh Xay and Ban Thamuang were significantly correlated (Annex Table 29).

Figure 34 Loge-transformed average monthly fisher catch rates by site for Cirrhinus lobatus (left) and Henicorhynchus siamensis (right).

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Figure 35 Loge-transformed average monthly fisher catch rates by site for Labeo chrysophekadion (left) and Puntioplites proctozystron (right).

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Figure 36 Loge-transformed average monthly fisher catch rates by site for Cirrhinus microlepis (left) and Poropuntius malcolmi (right).

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Figure 37 Loge-transformed average monthly fisher catch rates by site for Cosmochilus harmandi (left) and Yasuhikotakia modesta (right).

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PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 20100.00.10.20.30.40.50.60.70.80.91.0

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 20100.00.1

0.20.30.40.5

0.6

ln C

PU

E (k

g/da

y)

Tay Son

Sang Var

Koh Khne

Day Lo

Ou Run

Banfang

Pres Bang

Ban Thamuang

Ban Xinh Xay

Ban Pha O

2003 2004 2005 2006 2007 2008 2009 2010 2011

Year

0.0000.0010.0020.0030.0040.0050.0060.0070.008

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000.010.020.030.040.050.060.070.08

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000

0.005

0.010

0.015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.0000.0010.0020.0030.0040.0050.0060.0070.0080.009

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000

0.001

0.002

0.003

0.004

0.005

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000

0.001

0.002

0.003

0.004

0.005

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.00

0.01

0.02

0.03

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000.020.040.06

0.080.100.12

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000

0.005

0.010

0.015

0.020

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000.01

0.020.030.040.05

0.06

ln C

PU

E (k

g/da

y)

Tay Son

Sang Var

Koh Khne

Day Lo

Ou Run

Banfang

Pres Bang

Ban Thamuang

Ban Xinh Xay

Ban Pha O

Figure 38 Loge-transformed average monthly fisher catch rates by site for Pangasius pleurotaenia (left) and Pangasius larnaudii (right).

2003 2004 2005 2006 2007 2008 2009 2010 2011

Year

0.000.010.020.030.040.050.060.070.080.09

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.00.10.20.30.40.50.60.70.80.9

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000.010.020.030.040.050.060.070.080.09

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.0

0.5

1.0

1.5

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.00.10.20.30.40.50.60.70.8

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000.010.020.030.040.050.060.070.080.09

ln C

PU

E (k

g/da

y)2003 2004 2005 2006 2007 2008 2009 2010 2011

0.0

0.1

0.2

0.3

0.4

0.5

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 2011

0.00

0.05

0.10

0.15

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000

0.005

0.010

0.015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 2011-0.00000015-0.00000010

-0.000000050.000000000.000000050.00000010

0.00000015

ln C

PU

E (k

g/da

y)

Tay Son

Sang Var

Koh Khne

Day Lo

Ou Run

Banfang

Pres Bang

Ban Thamuang

Ban Xinh Xay

Ban Pha O

2003 2004 2005 2006 2007 2008 2009 2010 2011

Year

0.000

0.001

0.002

0.003

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.00

0.05

0.10

0.15

0.20

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.0000.0010.0020.0030.0040.0050.0060.0070.008

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.00

0.01

0.02

0.03

0.04

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000.010.020.030.040.050.060.070.080.090.10

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.00

0.01

0.02

0.03

0.04

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000

0.0020.0040.0060.008

0.0100.012

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 2011-0.00000015-0.00000010-0.000000050.00000000

0.000000050.000000100.00000015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.00

0.01

0.02

0.03

0.04

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000

0.005

0.010

0.015

ln C

PU

E (k

g/da

y)

Tay Son

Sang Var

Koh Khne

Day Lo

Ou Run

Banfang

Pres Bang

Ban Thamuang

Ban Xinh Xay

Ban Pha O

Integrated analyses


Page 74

Figure 39 Loge-transformed average monthly fisher catch rates by site for Pangasius conchophilus (left) and Hemibagrus nemurus (right).

2003 2004 2005 2006 2007 2008 2009 2010

Year

-0.00000015-0.00000010

-0.000000050.000000000.000000050.00000010

0.00000015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010-0.00000015

-0.00000010-0.000000050.000000000.00000005

0.000000100.00000015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010

-0.00000010-0.00000015

-0.000000050.00000000

0.000000050.000000100.00000015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010-0.00000015-0.00000010-0.000000050.00000000

0.000000050.000000100.00000015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010-0.00000015-0.00000010-0.00000005

0.000000000.000000050.000000100.00000015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010-0.00000015-0.00000010

-0.000000050.000000000.000000050.00000010

0.00000015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010-0.00000015

-0.00000010-0.000000050.000000000.00000005

0.000000100.00000015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 20100.000.010.020.030.040.050.060.07

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 20100.00

0.05

0.10

0.15

0.20

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 20100.0

0.1

0.2

0.3

0.4

ln C

PU

E (k

g/da

y)

Tay Son

Sang Var

Koh Khne

Day Lo

Ou Run

Banfang

Pres Bang

Ban Thamuang

Ban Xinh Xay

Ban Pha O

2003 2004 2005 2006 2007 2008 2009 2010 2011

Year

0.0000.0010.0020.0030.0040.0050.0060.0070.008

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.0

0.1

0.2

0.3

0.4

0.5

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.00

0.05

0.10

0.15

0.20

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.00.10.20.30.40.50.60.70.80.91.0

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.0

0.5

1.0

1.5

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 2011-0.00000015-0.00000010

-0.000000050.000000000.000000050.00000010

0.00000015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.000

0.005

0.010

0.015

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.0

0.1

0.2

0.3

ln C

PU

E (k

g/da

y)

2003 2004 2005 2006 2007 2008 2009 2010 20110.0

0.5

1.0

1.5

2.0

ln C

PU

E (k

g/da

y)2003 2004 2005 2006 2007 2008 2009 2010 2011

0.000

0.005

0.010

0.015

ln C

PU

E (k

g/da

y)

Tay Son

Sang Var

Koh Khne

Day Lo

Ou Run

Banfang

Pres Bang

Ban Thamuang

Ban Xinh Xay

Ban Pha O

6.3.2 Spawning locations

Linear regressions were fitted to a possible 161 combinations of species-wise estimates of mean larvae density in Mekong River and spawning stock biomass at the lee trap fishery site, and at each of the 10 fisher catch monitoring locations included under both the AMCF and FEVM programmes. Larvae density was expected to increase (linearly) with spawning stock size, but this response was evident for just less than half of the species-site combinations, and only six regression coefficients were judged to be significant at the 5 % level (Table 12). With 161 regressions, at least six would be expected to be significant by chance alone.

The density of larvae belonging to the Henicorhynchus genus responded positively to their spawning stock biomass estimates at the lee trap fishery in Southern Lao PDR. The larvae density of P. pleurotaenia, P. conchophilus and H. nemurus also increased as a linear function of the spawning stock biomass index measured at the lee trap fishery. However, for P. larnaudii this response was significantly (p < 0.05) negative.

The density of larvae of P. pleurotaenia declined significantly with spawning stock biomass estimated for Pres Bang but, increased significantly with spawning stock biomass at Tay Son. The larvae density of P. conchophilus also increased significantly with stock biomass measured at Pres Bang. For Y. modesta the response was significantly negative at Sang Var.

No evidence was found to suggest that significant (p < 0.05) larvae density–spawning stock biomass responses for any particular species were consistently positive or negative among the monitoring sites.

Important spawning locations for all species, judged in terms of the observed and expected frequency of positive responses of larval density to spawning stock biomass, were not evident in the dataset.

Larvae density estimates at Tonle Sap increased with spawning stock size for 105 of the 182 species-site combinations-significantly more than would be expected by chance (p < 0.05) (Table 13).

The frequency of positive larvae density-spawning stock biomass responses at both Ban Pha O and for the lee trap fishery was significantly greater than would be expected by chance (p < 0.05) suggesting that important spawning locations may exist at or above these locations. However, only three of the 32 responses examined for these two locations were positive and significant at the 5 % level. Nine other significant responses were detected in the dataset, although five were negative and no consistent patterns were evident.

The density of larvae belonging to the Henicorhynchus genus responded positively (but not significantly) to their spawning stock biomass estimates at the lee trap fishery in southern Lao PDR consistent with the findings for larvae sampled from the Mekong River.

Integrated analyses


Page 76

Table 12

Coefficients of linear regressions betw

een estimates of larvae density in the M

ekong River at Phnom Penh and spaw

ning stock biomass at the 10 locations

included under both the AMC

F and FEVM fisher catch m

onitoring programm

es and at the Lee trap fishery in southern Lao PDR.

Larvae Species nam

eSSB

Species Nam

e

Ban Pha O

Ban Thamuang

Ban Xinh Xay

Banfang

Lee Trap

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Count (+)

Count (-)

Expected

Expected

p

Henicorhynchus siam

ensisH

enicorhynchus sp. .

4.3

1

00.5

0.50.32

Henicorhynchus siam

ensisH

enicorhynchus siamensis

-26.9-19.7

-973.3-71.6

-245.2

7.1-3.4

-17.512.4

-828.72

85

50.06

Labeo chrysophekadionLabeo chrysophekadion

-34.512.3

-4.3-5.2

-2.4

-1.2-1.0

-2.112.4

89.83

64.5

4.50.32

Puntioplites proctozystronPuntioplites proctozystron

-652.2

4.5-38.9

18.2

-23.6-64.6

3.3256.1

4.15

44.5

4.50.74

Cirrhinus m

icrolepisC

irrhinus microlepis

1045.1

-1.1

-6.0

38.3-0.1

20.5220.6

4

33.5

3.50.71

Cosm

ochilus harmandi

Cosm

ochilus harmandi

-1.91.0

-1.0-71.7

-13.5

-5.7-5.6

-10.7-34.7

1

84.5

4.50.02

Yasuhikotakia modesta


75.2-98.3

-464.3

-322.0

-93.5589.6

97.6-261.6*

-718.93

64.5

4.50.32

Pangasius pleurotaeniaPangasius pleurotaenia

1589.6

-15.9-89.0

60.6203.2

575.3-56.5

-5956.7*74.0

5831.9*6

45

50.53

Pangasius larnaudiiPangasius larnaudii

-84.5

40.4

-0.1*6.7

-53.61.5

8.4-11.3

4.95

44.5

4.50.74

Pangasius conchophilusPangasius conchophilus

-942.62.2

-0.5

0.0-3.7

-28.1-4.5

562*-11.9

3

64.5

4.50.32

Hem

ibagrus nemurus

Hem

ibagrus nemurus

-2.7-44.9

10.2

0.3

1

32

20.32

Henicorhynchus spp.

Cirrhinus lobatus

119.1161.0

845.021.9

150.9

1.8-1.6

57.3-265.9

7

24.5

4.50.10

Henicorhynchus spp.

Henicorhynchus siam

ensis28.1

40.3528.4

40.1

127.83.7

-4.735.8

3.8-43.7

82

55

0.06H

enicorhynchus spp.H

enicorhynchus sp.

1.2

10

0.50.5

0.32Pangasius sp.1

Pangasius pleurotaenia172.3

-10.8

-280.6-1.3

-134.8-517.0

27.1-1166.2

-59.94205.4

37

55

0.21Pangasius sp.1

Pangasius larnaudii

10.1

-47.90.0

25.6-63.0

-0.19.5

29.0-450.2

54

4.54.5

0.74Pangasius sp.1

Pangasius conchophilus-186.1

17.8-0.1

0.0

-15.4-29.7

-1.1338.5

-2.1

36

4.54.5

0.32Pangasius sp.2

Pangasius pleurotaenia-278.8

87.2

-59.2-138.7

-139.5497.1

-12.4-484.1

47.5-2523.1

37

55

0.21Pangasius sp.2

Pangasius larnaudii

-0.7

27.7-0.1

-10.5-1.4

3.8-8.2

-34.558.6

36

4.54.5

0.32Pangasius sp.2

Pangasius conchophilus56.4

-16.40.6

0.2

11.5-3.6

4.2-91.2

15.2

63

4.54.5

0.32

Count (+)

77

64

87

65

99

672

8980.5

80.50.18

C

ount (-)8

57

104

1011

128

85

Expected

7.56

6.57

68.5

8.58.5

8.58.5

5.5

Expected7.5

66.5

76

8.58.5

8.58.5

8.55.5

p

0.800.56

0.780.11

0.250.47

0.230.09

0.810.81

0.76

Note: * p < 0.05; ** p < 0.01.

Tabl

e 13

Coe

ffici

ents

of l

inea

r reg

ress

ions

bet

wee

n es

timat

es o

f lar

vae

dens

ity in

the

Tonl

e Sa

p at

Phn

om P

enh

and

spaw

ning

stoc

k bi

omas

s at t

he 1

0 lo

catio

ns in

clud

ed u

nder

bo

th th

e AM

CF

and

FEVM

fish

er c

atch

mon

itori

ng p

rogr

amm

es a

nd a

t the

Lee

trap

fish

ery

in so

uthe

rn L

ao P

DR.

Lar

vae

Spec

ies n

ame

SSB

Spe

cies

Nam

e

Ban Pha O

Ban Thamuang

Ban Xinh Xay

Banfang

Lee Trap

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Count (+)

Count (-)

Expected

Expected

p

Hen

icor

hync

hus s

iam

ensi

sH

enic

orhy

nchu

s sp.

2.2

10

0.5

0.5

0.32

Hen

icor

hync

hus s

iam

ensi

sH

enic

orhy

nchu

s sia

men

sis

-31.

4-3

2.5

-911

.8-7

7.5*

-267

.5**

2.0

2.9

-37.

65.

4-6

77.4

37

55

0.21

Labe

o ch

ryso

phek

adio

nLa

beo

chry

soph

ekad

ion

-14.

687

.26.

320

.9

5.3

4.9

1.6

-166

.5-2

8.3

-124

.86

45

50.

53Pu

ntio

plite

s pro

ctoz

ystro

nPu

ntio

plite

s pro

ctoz

ystro

n

-4

5.3

-38.

6

78.1

-31.

414

3.8

12.7

77.4

-8.9

44

44

1.00

Cir

rhin

us m

icro

lepi

sC

irrh

inus

mic

role

pis

2645

.9

37

.6

35.5

-75.

75.

37.

471

6.0

6

13.

53.

50.

06C

osm

ochi

lus h

arm

andi

Cos

moc

hilu

s har

man

di3.

9-2

.7-1

.181

6.8

13

.2-3

9.1

7.7

21.9

358.

9

63

4.5

4.5

0.32

Yasu

hiko

taki

a m

odes

taYa

suhi

kota

kia

mod

esta

631*

52.6

-1

174.

0

3151

.723

26.2

3301

.394

4.9

-753

.6-5

941.

66

34.

54.

50.

32Pa

ngas

ius p

leur

otae

nia

Pang

asiu

s ple

urot

aeni

a39

4.5

56

0.3

-115

5.9

220.

1-1

415.

8-1

378.

2-3

2.5

-701

9.8

-303

.079

76.7

46

55

0.53

Pang

asiu

s lar

naud

iiPa

ngas

ius l

arna

udii

-7

8.2

89

.6-0

.135

.4-1

16.6

0.8

5.3

-17.

9-4

57.6

45

4.5

4.5

0.74

Pang

asiu

s con

chop

hilu

sPa

ngas

ius c

onch

ophi

lus

778.

033

.10.

6

0.1

-13.

6-7

2.3

5.7

255.

314

.8

72

4.5

4.5

0.10

Hem

ibag

rus n

emur

usH

emib

agru

s nem

urus

-27.

5-1

12.5

*

-9.5

03

1.5

1.5

0.08

Hen

icor

hync

hus s

pp.

Cir

rhin

us lo

batu

s15

3.8

172.

910

67.3

5.4

94

.2-1

.0-1

.157

.429

3.6

7

24.

54.

50.

10H

enic

orhy

nchu

s spp

.H

enic

orhy

nchu

s sia

men

sis

30.2

51.5

667.

249

.7

110.

21.

1-3

.033

.10.

5-6

19.1

82

55

0.06

Hen

icor

hync

hus s

pp.

Hen

icor

hync

hus s

p.

0.

03

1

00.

50.

50.

32Pa

ngas

ius s

p.1

Pang

asiu

s ple

urot

aeni

a14

7.3

-2

4.9

-251

.543

.213

7.3

602.

7-3

7.1

-648

9.7

85.3

6863

.46

45

50.

53Pa

ngas

ius s

p.1

Pang

asiu

s lar

naud

ii

*-90

.3*

51

.50.

019

.7-9

9.9

3.1

8.8

-18.

1-2

50.1

54

4.5

4.5

0.74

Pang

asiu

s sp.

1Pa

ngas

ius c

onch

ophi

lus

1155

.6*

13.8

-0.1

0.

022

.6-5

2.9

5.5

-111

.53.

8

63

4.5

4.5

0.32

Pang

asiu

s sp.

2Pa

ngas

ius p

leur

otae

nia

547.

0

-116

.052

.8

381.

114

36.9

**-1

7.2

-302

1.0

219.

1*

53

44

0.48

Pang

asiu

s sp.

2Pa

ngas

ius l

arna

udii

-6

4.2

11

8.3*

8.

0-3

6.0

0.0

-5.2

-38.

4

34

3.5

3.5

0.71

Pang

asiu

s sp.

2Pa

ngas

ius c

onch

ophi

lus

906.

6-1

9.3

-0.9

58.8

*-1

8.6

3.4

-373

.6-7

.8

35

44

0.48

Pang

asiu

s sp.

3Pa

ngas

ius p

leur

otae

nia

2747

.9*

23

9.3

-454

.2

-236

.730

2.3

-126

.7-1

1752

.6*

-27.

1

35

44

0.48

Pang

asiu

s sp.

3Pa

ngas

ius l

arna

udii

-1

56.3

26

.00.

0-6

.4-1

27.3

12.3

13.1

-56.

19.

55

44.

54.

50.

74Pa

ngas

ius s

p.3

Pang

asiu

s con

chop

hilu

s19

73.2

33.8

1.8

0.

1-1

0.1

-76.

115

.0-2

19.8

42.5

6

34.

54.

50.

32C

ount

(+)

137

710

914

714

910

310

577

9191

0.04

Cou

nt (-

)3

78

62

613

610

96

Expe

cted

87

7.5

85.

510

1010

9.5

9.5

4.5

p0.

011.

000.

800.

320.

030.

070.

180.

070.

820.

820.

32

Not

e: *

p <

0.0

5; *

* p

< 0.

01

Integrated analyses


Page 78

6.3.3 Recruitment effects on stocks migrating from the TS-GL

The multi-species assemblage (all species combined)

The recruitment index for the entire multi-species assemblage varied by more than an order of magnitude during the monitoring period (Figure 40). The arithmetic mean density-based estimate was significantly higher in 2004 compared to the geometric equivalent. This is likely to reflect the very high density of Henicorhynchus species larvae estimated for that particular year (see Section 5.3.3). These extreme values would have a large influence on the arithmetic mean larvae density estimate compared to other years. Estimates for 2003 are unlikely to be either precise or accurate because of the small sample size that year. Estimates for 2002 may also be biased owing to the lack of observations during June when densities are typically high.

The abundance and biomass for the multi-species assemblage migrating from the TS-GL system with the receding flood waters each year between October and March indicated by the dai fishery catch rates were found to increase with the RI estimated for the earlier flooding period (June–September) (Figure 41).

0

5E+11

1E+12

2E+12

2E+12

3E+12

3E+12

4E+12

4E+12

2002 2003 2004 2005 2006 2007 2008 2009

Year

AM

Rec

ruitm

ent I

ndex

(lar

vae)

0

1E+11

2E+11

3E+11

4E+11

5E+11

6E+11

GM

Rec

ruitm

ent I

ndex

(lar

vae)

AM densityGM density

Figure 40 Estimates of the annual recruitment index, RI for the TS-GL system, 2002–2009 calculated as the product of the arithmetic mean (AM) or geometric mean (GM) daily larvae density estimate, the mean daily inflow of water and inflow duration (days).

The recruitment index estimates could comfortably support the estimated annual catch rates for the dai fishery even assuming that 90 % of the recruits were caught in the TS-GL system by other fisheries and if the average larvae survival rate each season was between 6 % and 7 %. This also assumes that the dai fishery catches approximately 80 % of the remaining recruits based upon depletion modeling results reported by Halls et al. (2011).

Applying fixed rates of survival of 2 % and 10 % to the geometric and arithmetic mean larvae density estimates respectively generates dai fishery catch rate predictions similar to those observed although high catch rates tend to be over-estimated and low catch rates under-estimated (Figure 42)

y = 4E-13x + 5.1594R2 = 0.7088

4

4.5

5

5.5

6

6.5

7

0 5E+11 1E+12 1.5E+12 2E+12 2.5E+12 3E+12 3.5E+12 4E+12

RI (AM)

ln D

ai C

PUE

(t/da

i/sea

son)

y = 3E-12x + 5.0419R2 = 0.8031

4

4.5

5

5.5

6

6.5

7

0 1E+11 2E+11 3E+11 4E+11 5E+11 6E+11

RI (GM)

ln D

ai C

PUE

(t/da

i/sea

son)

y = 2E-13x + 16.824R2 = 0.4494

16

16

17

17

17

17

17

18

18

18

18

0 5E+11 1E+12 1.5E+12 2E+12 2.5E+12 3E+12 3.5E+12 4E+12

RI (AM)

Dai

CPU

E (n

/dai

/sea

son)

y = 2E-12x + 16.679R2 = 0.6972

16

16.5

17

17.5

18

18.5

0 1E+11 2E+11 3E+11 4E+11 5E+11 6E+11

RI (GM)ln

Dai

CPU

E (t/

dai/s

easo

n)

Figure 41 Loge-transformed dai catch rates (2004–05 to 2009–10) plotted as a function of the annual recruitment index, RI estimated from (top row) arithmetic mean daily larvae density and (bottom row) geometric mean daily larvae density between June and September each year.

Integrated analyses


Page 80

Of course, the observed dai catch rates can be predicted without error by allowing the larvae survival rate to vary each year and minimizing the sum of squared deviations between the observed and predicted catch rates. After omitting observations for 2002 and 2003 for the reasons described above, the estimated arithmetic mean larvae survival rates are estimated to have varied from between approximately 1 % and 22 % assuming a constant removal proportion (0.9) by other fisheries in the TS-GL system (Figure 43). Larvae survival rates are likely to be lower than this because it was assumed that all fish caught in the TS-GL system were aged 0+. In reality, other age groups in the population will also be vulnerable to capture depending upon the longevity of the species.

0

200

400

600

800

1000

1200

1400

2002 2003 2004 2005 2006 2007 2008 2009

Season

CPU

E (t/

dai/s

easo

n)

Obs CPUEPred CPUE GM 10 % survivalPred CPUE AM 2 % survival

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

2004 2005 2006 2007 2008 2009

Year

Lara

ve s

urvi

val

Figure 42 Observed and predicted dai catch rates estimated as the product of the arithmetic (AM) or geometric mean (GM) daily larvae densities (June–September), the mean daily flow into the TS-GL system (June–September), the observed mean weight of fish caught each year and larvae survival rates (10 % for the GM daily larvae density estimate and 2 % of the AM equivalent). It is assumed that 90 % of the recruits are landed by other fisheries and that the dai fishery catches approximately 80 % of the remaining recruits.

Figure 43 Estimated larvae survival rates applied to the arithmetic mean larvae density to generate the observed dai catch rates for the observed mean fish weights between 2004 and 2009.

These predicted survival rates appear to vary with the RI according to a power function, suggesting that survival or mortality rates of larvae may be density-dependent (Wootton, 1990) (Figure 44). A similar response is found if geometric mean larvae density estimates are applied instead.

If this is the true underlying response of larvae survival rates to larvae density, then dai fishery catches and catch rates may be predicted from larvae densities monitored each year in the Tonle Sap, estimates of flow into the TS-GL system between June and September and observations or predictions of the mean fish weight (Figure 45). Mean fish weight can be predicted from the flood index exponential model described in Section 2.5.

y = 47678265.1742x-0.7753

R 2 = 0.9266

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

0 5E+11 1E+12 2E+12 2E+12 3E+12 3E+12 4E+12 4E+12

RI y

Pred

icte

d la

rvae

sur

viva

l

y = 0.7753x - 17.68

R 2 = 0.9266

0.0

1.0

2.0

3.0

4.0

5.0

6.0

24 25 26 27 28 29 30

ln RIy

Pred

icte

d la

rvae

mor

talit

y, M

Figure 44 Predicted survival rates of larvae plotted as a power function of the larvae recruitment index

(above) and equivalent instantaneous natural mortality rates plotted as a function of loge-transformed recruitment index (below). Estimates are for 2004–2009 generated using AM daily larvae density estimates.

Integrated analyses


Page 82

Alternatively, the regression models illustrated in Figure 41 and reproduced below (Figure 46) offer simpler models to estimate dai catch rates using only the RI as a predictor. These models elegantly encapsulate the effects of both larvae transport (a function of flow and larvae density) on fish recruitment (abundance), and flooding extent (a function of flow) on fish growth.

0

200

400

600

800

1000

1200

97-98

98-99

99-00

00-01

01-02

02-03

03-04

04-05

05-06

06-07

07-08

08-09

09-10

Season

CPU

E (t/

dai/s

easo

n)

Observed CPUE (t/dai/season)

Predicted CPUE (t/dai/season)

0

200

400

600

800

1000

1200

97-98

98-99

99-00

00-01

01-02

02-03

03-04

04-05

05-06

06-07

07-08

08-09

09-10

Season

CPU

E (t/

dai/s

easo

n)

Observed CPUE (t/dai/season)

Predicted CPUE (t/dai/season)

Figure 45 Observed versus predicted dai catch rates. The upper figure shows catch rates predicted using arithmetic mean larvae density estimates, the lower figure shows the geometric-mean based equivalent. Larvae survival rates are predicted to vary in the density-dependent manner illustrated in Figure 44 and its geometric-mean larvae density-based equivalent.

Selected species

As expected, coefficients for the regressions used to examine the linear dependence of relative abundance and biomass indices on their arithmetic mean daily larvae density-based recruitment index were also positive for all of the selected species except for the abundance index for Pangasius conchophilus and for Pangasius sp.1 versus P. pleurotaenia (Table 14). Regression coefficients were significant (p < 0.05) for estimates of the RI for Henicorhynchus species and dai catch rates for Cirrhinus lobatus, and for the combined catch rate observations for Cirrhinus lobatus and Henicorhynchus siamensis.

y = 4E-13x + 5.1594R2 = 0.7088

4

4.5

5

5.5

6

6.5

7

05E+11

1E+121.5E+12

2E+122.5E+12

3E+123.5E+12

4E+12

RI (AM)

ln D

ai C

PUE

(t/da

i/sea

son)

y = 3E-12x + 5.0419R2 = 0.8031

4

4.5

5

5.5

6

6.5

7

0 1E+11 2E+11 3E+11 4E+11 5E+11 6E+11

RI (GM)

ln D

ai C

PUE

(t/da

i/sea

son)

Figure 46 loge-transformed dai CPUE plotted as a function of the arithmetic (top) and geometric (bottom) mean daily larvae density-based recruitment index.

Both regressions are significant at p < 0.05.

Integrated analyses


Page 84

Table 14 Regression coefficients of the linear relationship between estimates of the arithmetic mean daily larvae density-based recruitment index and loge-transformed dai catch rates.

Larvae Species name Dai Species Name ln CPUE (t/dai/season) R2 ln CPUE

(n/dai/season) R2 Size

Henicorhynchus siamensis Henicorhynchus siamensis 2.20E-12 0.08 2.58E-12 0.08 SmallLabeo chrysophekadion Labeo chrysophekadion 3.50E-12 0.13 2.44E-12 0.05 LargePuntioplites proctozystron Puntioplites proctozystron 3.70E-12 0.58 2.68E-12 0.37 SmallCirrhinus microlepis Cirrhinus microlepis 6.50E-12 0.3 5.64E-12 0.34 LargePoropuntius malcolmi Poropuntius malcolmi 6.03E-12 0.48 5.22E-12 0.49 MediumCosmochilus harmandi Cosmochilus harmandi 9.92E-12 0.05 1.30E-11 0.15 GiantYasuhikotakia modesta Yasuhikotakia modesta 4.29E-12 0.32 4.56E-12 0.38 SmallPangasius pleurotaenia Pangasius pleurotaenia 6.66E-13 0.32 2.81E-13 0.09 MediumPangasius larnaudii Pangasius larnaudii 1.90E-11 0.14 1.28E-11 0.07 GiantPangasius conchophilus Pangasius conchophilus 1.63E-12 0.01 -3.95E-13 0 GiantHemibagrus nemurus Hemibagrus nemurus 6.20E-11 0.21 5.19E-11 0.14 LargeHenicorhynchus spp. Cirrhinus lobatus 0.40E-13* 0.67 3.69E-13 0.7 SmallHenicorhynchus spp. Henicorhynchus siamensis 3.80E-13 0.37 4.04E-13 0.28 SmallHenicorhynchus spp. Cirrhinus lobatus or

Henicorhynchus siamensis3.80E-13* 0.47 3.9E-13* 0.35 Small

Pangasius sp.1 Pangasius pleurotaenia 3.07E-12 0.13 -1.40E-13 0 MediumPangasius sp.1 Pangasius larnaudii 1.30E-11 0.29 7.83E-12 0.12 GiantPangasius sp.1 Pangasius conchophilus 1.19E-11 0.57 7.74E-12 0.32 GiantPangasius sp.2 Pangasius pleurotaenia 2.01E-10 0.25 7.57E-11 0.06 MediumPangasius sp.2 Pangasius larnaudii 4.80E-10 0.18 3.00E-10 0.08 GiantPangasius sp.2 Pangasius conchophilus 5.35E-10 0.52 3.63E-10 0.31 GiantPangasius sp.3 Pangasius pleurotaenia 2.66E-11 0.21 5.11E-12 0.01 MediumPangasius sp.3 Pangasius larnaudii 1.30E-10 0.63 1.03E-10 0.44 GiantPangasius sp.3 Pangasius conchophilus 6.08E-11 0.32 4.97E-11 0.28 Giant

Count (+) 23 21 Count (-) 0 2 Expected 10 10 Expected 10 10 p 0.00 0.00

Note: * p < 0.05; ** p < 0.01

6.3.4 Extent of fish migrations from the TS-GL

A possible 105 functional dependencies were tested for indices of relative biomass (Table 15) and a possible 99 for indices of stock abundance (Table 16). The difference in the number of possible regressions arose because the number of fish caught in the lee trap fishery was not monitored every year, see (Section 3.3). Relative spawning stock biomass at sites in the basin increased with relative stock biomass migrating from the TS-GL system for 51 species-site combinations – a frequency that could be expected by chance (Table 15). However, the frequency of positive regression coefficients for L. chysophekadion and P. malcolmi were both higher than would be expected by chance. Positive coefficients were also found for Henicorhynchus species landed by the lee trap fishery and C. lobatus and H. siamensis landed by the dai fishery – the latter significant at the 5 % level. Other coefficients judged to be significant (p < 0.05) were P. conchophilus at Ban Xinh Xay and Ou Run, C. lobatus at Koh Khne and Y. modesta at Tay Son.

The frequency of a positive response between relative spawning stock abundance for species at sites in the basin and estimates of their relative stock biomass migrating from TS-GL system could also have been expected by chance (Table 16). Only one (positive) coefficient (H. siamensis at Sang Var) was judged to be significant (p < 0.05).

Integrated analyses


Page 86

Table 15 Regression coefficients of the linear dependence of relative spaw

ning stock biomass at locations in the LM

B indicated by mean catch rates (kg/day) betw

een April and Septem

ber each year and estimates of relative stock biom

ass migrating from

the TS-GL each year indicated by dai fishery catch rates (t/dai/season) in the

preceding dai fishing season (October to M

arch).

Species name

Ban Pha O

Ban Thamuang

Ban Xinh Xay

Banfang

Lee Trap

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Count (+)

Count (-)

Expected

Expected

p

Cirrhinus lobatus

1.59E-069.58E-07

-6.83E-092.8E-06†

8.95E-071.68E-07

5.1E-06*

-5.38E-06-1.50E-06

-3.00E-07

64

55

0.53H

enicorhynchus siamensis

-2.39E-06-2.32E-06

-3.08E-085.2E

-06*†-2.97E-06

-6.74E-07-3.79E-08

-4.61E-06-1.47E-06

2.00E-061.42E-07

38

5.55.5

0.13Labeo chrysophekadion

3.66E-067.32E-06

1.14E-05

1.33E-053.58E-05

4.88E-051.32E-05

9.10E-071.96E-06

-1.36E-069

15

50.01

Puntioplites proctozystron-1.69E-06

-3.12E-06

-4.36E-06

1.34E-05-7.29E-06

1.27E-067.53E-05

-1.16E-073.08E-04

45

4.54.5

0.74C

irrhinus microlepis

-3.93E-07

2.98E-065.74E-07

1.33E-061.58E-05

-1.07E-061.89E-06

5

23.5

3.50.26

Poropuntius malcolm

i2.23E-04

1.19E-044.83E-06

3.50E-06

-7.28E-052.01E-05

5.18E-056.99E-07

71

44

0.03C

osmochilus harm

andi-6.05E-05

3.06E-042.64E-05

-7.09E-07

-2.23E-061.64E-05

2.47E-06-2.28E-06

-1.19E-06

45

4.54.5

0.74Yasuhikotakia m

odesta-1.95E-06

-2.09E-06

-5.30E-08

-2.38E-071.26E-07

-1.46E-07-4.81E-07

3.39E-071.90E

-07*3

64.5

4.50.32

Pangasius pleurotaenia-9.48E-07

3.81E-06

-1.5E-04-1.56E-06

-1.60E-06-3.39E-07

1.86E-06-1.47E-08

-5.69E-061.60E-08

37

55

0.21Pangasius larnaudii

-1.30E-05

-1.2E-04

-1.98E-06-5.96E-06

-6.22E-084.67E-05

-1.06E-05-5.75E-06

5.86E-062

74.5

4.50.10

Pangasius conchophilus-1.24E-05

-0.0014.32E

-04*4.4E-04

-1.80E-05

3.70E-061.14E

-04*-4.30E-07

7.43E-06

54

4.54.5

0.74H

emibagrus nem

urus-1.55E-04

-1.71E-05-1.09E-05

-1.4E-04

04

22

0.05C

ount (+)3

45

34

47

83

55

5154

52.552.5

0.77C

ount (-)8

54

36

74

38

51

Expected5.5

4.54.5

35

5.55.5

5.55.5

53

Expected5.5

4.54.5

35

5.55.5

5.55.5

53

p0.13

0.740.74

1.000.53

0.370.37

0.130.13

1.000.10

Note: * p < 0.05; ** p < 0.01. †R

egressed with catch rates for H

enicorhynchus species for the lee trap fishery.

Tabl

e 16

Regr

essi

on c

oeffi

cien

ts o

f the

line

ar d

epen

denc

e of

rela

tive

abun

danc

e of

spaw

ning

stoc

k si

ze a

t loc

atio

ns in

the

LMB

indi

cate

d by

mea

n ca

tch

rate

s

(n

/day

) bet

wee

n Ap

ril a

nd S

epte

mbe

r eac

h ye

ar a

nd e

stim

ates

of r

elat

ive

abun

danc

e of

the

stoc

k m

igra

ting

from

the

TS-G

L ea

ch y

ear i

ndic

ated

by

dai

fishe

ry c

atch

rate

s (n/

dai/s

easo

n) in

the

prec

edin

g da

i fish

ing

seas

on (O

ctob

er to

Mar

ch).

Spec

ies n

ame

Ban Pha O

Ban Thamuang

Ban Xinh Xay

Banfang

Lee Trap

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Count (+)

Count (-)

Expected

Expected

p

Cir

rhin

us lo

batu

s4.

82E-

085.

20E-

08-1

.56E

-09

-1.

13E-

075.

53E-

083.

05E-

07-2

.45E

-07

1.44

E-08

-5.4

0E-0

9

63

4.5

4.5

0.32

Hen

icor

hync

hus s

iam

ensi

s-2

.53E

-07

-4.3

3E-0

7-4

.11E

-09

--6

.83E

-08

-1.4

9E-0

82.

83E-

07-1

.78E

-07

-5.7

2E-0

93.

97E

-07*

-7.7

0E-0

82

85

50.

06La

beo

chry

soph

ekad

ion

-2.0

1E-0

86.

58E-

08-1

.84E

-07

-7.

17E-

087.

27E-

08-5

.99E

-08

-6.1

9E-0

75.

11E-

08-1

.48E

-07

-2.1

6E-0

74

65

50.

53Pu

ntio

plite

s pro

ctoz

ystro

n-1

.86E

-07

1.

92E-

07-

-1.2

4E-0

6-5

.98E

-07

-1.0

5E-0

6-1

.57E

-07

-2.3

9E-0

65.

81E-

08-5

.03E

-06

27

4.5

4.5

0.10

Cir

rhin

us m

icro

lepi

s6.

86E-

11

-

1.41

E-07

1.89

E-08

7.97

E-07

4.29

E-07

-1.0

1E-0

75.

02E-

07

61

3.5

3.5

0.06

Poro

punt

ius m

alco

lmi

-4.0

3E-0

4-3

.10E

-04

1.75

E-07

--2

.44E

-06

-8.6

6E-0

62.

02E-

052.

37E-

064.

25E-

07

4

44

41.

00C

osm

ochi

lus h

arm

andi

-3.7

2E-0

7-7

.77E

-06

2.17

E-08

--8

.26E

-08

1.70

E-07

1.51

E-06

-2.8

3E-0

64.

21E-

07-1

.04E

-06

4

54.

54.

50.

74Ya

suhi

kota

kia

mod

esta

1.65

E-08

-1.7

5E-0

6

-1.

10E-

08-3

.95E

-08

4.16

E-08

-2.2

0E-0

8-5

.76E

-09

9.16

E-08

1.76

E-07

54

4.5

4.5

0.74

Pang

asiu

s ple

urot

aeni

a-2

.00E

-07

2.

11E-

07-

1.97

E-07

-3.8

9E-0

8-7

.00E

-08

3.25

E-07

4.98

E-08

-2.4

5E-0

61.

30E-

085

44.

54.

50.

74Pa

ngas

ius l

arna

udii

3.

55E-

09

--2

.20E

-07

5.06

E-07

-2.5

9E-0

73.

14E-

061.

39E-

067.

18E-

06-3

.62E

-08

53

44

0.48

Pang

asiu

s con

chop

hilu

s-6

.76E

-07

1.11

E-05

8.23

E-05

-

-6.9

0E-0

62.

80E-

061.

34E-

053.

06E-

079.

03E-

05

62

44

0.16

Hem

ibag

rus n

emur

us-1

.50E

-05

-4.6

6E-0

6-2

.93E

-06

-

03

1.5

1.5

0.08

Cou

nt (+

)3

45

-5

57

56

62

4950

5050

0.92

Cou

nt (-

)8

54

-5

64

65

44

Expe

cted

5.5

4.5

4.5

-5

5.5

5.5

5.5

5.5

53

Expe

cted

5.5

4.5

4.5

-5

5.5

5.5

5.5

5.5

53

p0.

130.

740.

74-

1.00

0.76

0.37

0.76

0.76

0.53

0.41

Not

e: *

p <

0.0

5; *

* p

< 0.

01. †

Reg

ress

ed w

ith c

atch

rate

s for

Hen

icor

hync

hus s

peci

es fo

r the

lee

trap

fishe

ry.

Integrated analyses


Page 88

6.3.5 Extent of flood effects on fish growth

Of the 29 functional dependencies of fish growth on flooding extent and duration that could be tested, less than half were positive and at a frequency that could be expected by chance (Table 17). Only two responses, both negative, were judged significant (p < 0.05).

Table 17 Regression coefficients of the linear dependence of m

ean body weight of species sam

pled at fisher catch monitoring locations in

the basin during February each year on the flood extent and duration in the TS-GL system

indicated by the flood index.

Species name

Ban Xinh Xay

Banfang

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Count (+)

Count (-)

Expected

Expected

p

Cirrhinus lobatus

-1.9E

-06*

3.5E-07

-8.9E-07

1

21.5

1.50.56

Henicorhynchus siam

ensis

-1.4E-06

-3.5E-06

-1.2E-06*

-3.7E-061.5E-05

14

2.52.5

0.18Labeo chrysophekadion

-3.2E-07

-4.2E-073.9E-06

-1.2E-06

1

32

20.32

Puntioplites proctozystron

-1.2E-06

2.3E-063.8E-06

2

11.5

1.50.56

Cirrhinus m

icrolepis

-7.0E-06

-5.0E-07

0

21

10.16

Poropuntius malcolm

i

-3.2E-06-1.1E-06

1.0E-05

1

21.5

1.50.56

Cosm

ochilus harmandi

-2.4E-06

1.5E-076.3E-07

1.7E-06

31

22

0.32Yasuhikotakia m

odesta

1.7E-07

1

00.5

0.50.32

Pangasius larnaudii

5.3E-06

1

00.5

0.50.32

Pangasius conchophilus-2.1E-06

-3.7E-06

1.2E-06

1

21.5

1.50.56

Count (+)

00

12

60

21

1217

14.514.5

0.35C

ount (-)3

34

21

13

0Expected

1.51.5

2.52

3.50.5

2.50.5

Expected1.5

1.52.5

23.5

0.52.5

0.5p

0.080.08

0.181.00

0.060.32

0.650.32

Note: * p < 0.05; ** p < 0.01.

6.3.6 Management effects and recruitment

The dependence of mean fish weight caught in the dai fishery on the number of gear units confiscated could not be detected for any gear type confiscated. For gears for which a significant number of confiscations were made (e.g. fence traps, cylindrical traps), dai catch rates were found to respond significantly (p < 0.01) but negatively to the quantity confiscated after accounting for the estimated variation in recruitment each year. For the remaining gears, the quantity confiscated had no significant effect on dai catch rates (Table 18).

Therefore, gear confiscations appear not to have a detectable effect on either rates of exploitation or fish biomass. Furthermore, no obvious relationship was found between the index of recruitment to the TS-GL system in year y+1 and the biomass of fish migrating from the system indicated by dai catch rates in y/y+1 that would be expected to contribute to, or form, the spawning stock in year y+1 (Figure 47).

Table 18 Results of the GLM to test the dependence of dai catch rates on the quantity of fence (FENCE) confiscated each year after accounting for variation in recruitment (RIAMTSY).

Tests of Between-Subjects Effects Tests of Between-Subjects Effects

Dependent Variable: Dai CPUE (n/dai/season)

1.432E+15b 2 7.158E+14 41.465 .007 82.931 .9912.092E+15 1 2.092E+15 121.217 .002 121.217 1.0008.191E+14 1 8.191E+14 47.451 .006 47.451 .9901.173E+15 1 1.173E+15 67.982 .004 67.982 .9995.178E+13 3 1.726E+137.080E+15 61.483E+15 5

SourceCorrected ModelInterceptFENCERIAMTSYErrorTotalCorrected Total

Type III Sumof Squares df Mean Square F Sig.

Noncent.Parameter

ObservedPowera

Computed using alpha = .05a.

R Squared = .965 (Adjusted R Squared = .942)b.

Dependent Variable: Dai CPUE (n/dai/season)

4.2E+07 3833442 11.010 .002 30005906.10 54405353.87 11.010 1.000-27.595 4.006 -6.888 .006 -40.344 -14.846 6.888 .990

1.200E-05 .000 8.245 .004 7.366E-06 1.663E-05 8.245 .999

ParameterInterceptFENCERIAMTSY

B Std. Error t Sig. Lower Bound Upper Bound95% Confidence Interval Noncent.

ParameterObserved

Powera

Computed using alpha = .05a.

Parameter Estimates

Integrated analyses


Page 90

Figure 47 Recruitment in year y+1 and spawning stock biomass (SSB) indicated by dai catch rates in season y/y+1.

In spite of a relatively small SSB indicated by dai catch rates in 03–04, recruitment in 2004 was very high. Recruitment in 2005 was also relatively high for an above average spawning stock biomass but, very low in 2006 in spite of a very high SSB. The high biomass of spawners in 2006 was not however evident in the lee trap fishery. Because the fisher catch monitoring was not undertaken in 2006 it was not possible to confirm if this high SSB was evident at other locations in the LMB. The recruits (recruitment index) generated per the spawner index - an indicator of egg survival or spawning success, therefore appears to have been very high in 2004 before declining in 2005 and further still to more typical levels during and after 2006 (Figure 48).

Figure 48 Recruits (RI) per spawner index plotted through time.

6.4 Summary and conclusions

The small cyprinids examined exhibited broadly similar patterns of spatial and intra-annual variation in relative biomass consistent with the generalized migration and lifecycle model. Migrations of Cirrhinus lobatus and H. siamensis appear to extend as far upstream as Luang Prabang. Stung Treng province, Cambodia and the three tributaries in the Sesan basin appear to be important spawning locations for these species. Day Lo (Srepok River) appears to be the least important site, particularly in recent years. The relative biomass of these two species appears to have declined recently, particularly at Pres Bang. Furthermore, few fish of these species appear to have been caught upstream of the Khone Falls since June 2005. Catch rate correlations among pairs of sites suggest that C. lobatus may comprise a single stock with migrations from at least Koh Khne to northern Lao PDR. For H. siamensis, clusters of significant catch rates correlations above and below Ou Run might indicate that this species comprises two populations mainly distributed above and below the Khone Falls.

The biomass of the other small cyprinid examined (Puntioplites proctozystron) was also relatively high in 2004 and 2005 compared to the following years particularly at the tributary sites (Pres Bang, Banfang, and Day Lo). Yasuhikotakia modesta was found to be abundant in the Tonle Sap with catch rates peaking at the start and end of flooding. Peaks in catch rates, indicative migrations were evident during the spawning period in the Srepok River.

The relative biomass of medium and large cyprinids examined also appeared to be relatively higher in 2004 and 2005 compared to the following years. Labeo chrysophekadion was reported at all the

Integrated analyses


Page 92

monitoring sites but, was particularly abundant in northern Cambodia and northern Lao PDR possibly indicating the presence of two stocks.

Pangasius conchophilus was found to be particularly abundant in Ou Run and Ban Xinh Xay. It appeared mainly utilize the Srepok River in the Sesan basin. The relative biomass of this species showed no obvious decline during the monitoring period. However, at some sites for the other pangasiid species, biomass appeared to be relatively higher in 2004 and 2005 compared to the following years.

It therefore appears that most species largely conform to the general life cycle model described in Section 6.1 although the bagrid catfish examined (Hemibagrus nemurus) appeared to be found only in Lao PDR and therefore probably undertakes only limited migrations. The biomass index of most species examined appeared to be relatively higher in 2004 and 2005, than during the following months.

Attempts to identify spawning locations from comparisons of temporal variation in larvae density sampled at Phnom Penh with relative spawning stock biomass at the fisher catch monitoring sites were largely unsuccessful. Statistically significant functional dependence between larvae density and spawning stock size could be detected for only a small number of species-site combinations examined.

It may be that our indices of spawning stock size estimated for the fisher catch monitoring locations, and/or our estimates of larvae density for other species were simply too imprecise to detect the hypothesised response and thereby to identify potentially important spawning migration routes or locations.

The multi-species assemblage recruitment index estimated for the TS-GL system varied by more than an order of magnitude between 2004 and 2009, and was highest in 2004 and 2005. Dai catch rates during this period increased significantly in response to the recruitment index. These estimated annual fluxes of larvae (recruits) could comfortably support the estimated annual catch rates for the dai fishery even assuming that 90 % of the recruits were caught in the TS-GL system by other fisheries and if the average larvae survival rate each season was between 6 % and 7 %. It was also demonstrated that larvae survival may be density-dependent. The RI may prove to be a useful predictor of dai catch rates because it encapsulates the effects of both larvae transport (a function of flow and larvae density) on fish recruitment (abundance), and flooding extent (a function of flow) on fish growth.

As expected, dai catch rates for the selected species also increased in response to their recruitment index except for P. conchophilus and for P. pleurotaenia compared with larvae for Pangasius sp.1. The response was significant (p < 0.05) for C. lobatus and for C. lobatus and H. siamensis combined for estimates of the RI for Henicorhynchus species. As discussed in Section 6.3.2 it is likely that our estimates of larvae density were simply too imprecise to detect significant responses of abundance or biomass to the RI for other species. Coefficients of determination (R2) were however higher for small and medium-sized cyprinids compared to large and giant cyprinid and catfish species (Figure 49). This would be expected on the grounds that recruitment in smaller, short-lived species will have a greater influence on population abundance and biomass compared to populations of larger, longer-lived species comprising several recruited cohorts (age-groups).

Conclusions about the extent of fish migrations from the GL-TS system to other parts of the basin could not be drawn due to the lack of significant responses between estimates of spawning stock biomass at the fisher catch and lee trap monitoring locations, and the dai fishery on the Tonle Sap. The lack of significant responses may have arisen as a consequence of few and imprecise estimates of relative stock size for species landed at the 11 monitoring locations and by the dai fishery. These estimates are likely to be imprecise particularly for the fisher catch monitoring locations because only a very small proportion of the stock is likely to be sampled at each site. The lee trap is likely to sample a larger proportion of the stock. In this respect it is therefore noteworthy that positive regression coefficients for species landed at this fishery were observed for the most abundant species landed by the dai fishery i.e. C. lobatus and H. siamensis.

Giant Large Medium Small0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

R-s

quar

ed

Figure 49 Mean R2 value with S.E bars by size category for the species listed in. Table 14 (except Panagsius sp.1–3) for linear regressions between estimates of the arithmetic mean daily larvae density-based recruitment index and loge-transformed dai catch rates (t/dai/season).

Integrated analyses


Page 94

Unlike the significant dependence of mean weight (fish growth) on the flood index illustrated in Section 2.5 for the multispecies assemblage caught in the dai fishery, flooding effects on fish growth could not be detected among the selected species caught at the AMCF and FEVM fisher catch monitoring locations. This is probably unsurprising given that, unlike the dai fishery, mean weight estimates at these sites were available between only 2004 and 2010. During this period, there was relatively little variation in the flood index (Figure 50). Only when this variation increases, do flood effects on growth become detectable. In other words, the estimates of mean weight are likely to have been too imprecise to detect the flood effect on growth.

Gear confiscations by the Cambodian FiA had no detectable effect on either the mean size or relative biomass of fish migrating from the GL-TS system after accounting for the effects of the flood and recruitment indices.

No obvious relationship was found between the index of the size of the spawning stock migrating out of the GL-TS system each year and the subsequent index of recruitment back into the system.

It is therefore concluded that recruits per the spawner index–an indicator of egg survival or spawning success, was very high in 2004 before declining in 2005 and further still to more typical levels during and after 2006.

0

0.005

0.01

0.015

0.02

0.025

0 200000 400000 600000 800000 1000000 1200000

FI (km2 days)

Mea

n w

eigh

t (kg

)

03-04 to 09-10

97-98 to 02-03

Figure 50 Mean weight of fish caught by the dai fishery plotted as a function of the TS-GL Flood Index (FI) for (i) 2003–04 to 2009–10 with fitted regression model (red solid circles with broken line) and for (ii) 1997–98 to 2009–10 with fitted exponential model (open circles and solid line).

7 Conclusions and Recommendations

Whilst a comprehensive review of the fish and fisheries of the LMB has recently been published (MRC, 2010) this document describes the first attempt to compile and analyses, in an integrated manner, data and information generated by the four routine fisheries monitoring programmes that have been supported by the MRC Fisheries Programme since as early as 1994.

Time series of indices of relative fish assemblage diversity, abundance, biomass, mean weight, and recruitment have been illustrated and tabulated for up to 54 locations throughout the LMB, providing a valuable baseline for management performance evaluation and impact assessment purposes.

Trends in these indicators have been examined for the multispecies assemblage as well as for abundant species at more than 12 locations. Spatial and temporal patterns in these indicators have also been examined in an attempt to improve understanding of the migrations and dynamics of fish stocks in the LMB.

No compelling evidence was found of declines in indices of the relative biomass or average fish size (weight) of the multispecies assemblage seasonally utilizing the TS-GL system, or significant change in its species composition that might be attributable to increasing fishing pressure in response to a growing population. No significant downward trend in relative annual fish biomass was detected for species sampled from the lee trap fishery as they attempt to migrate through the Hoo Som Yai channel at the Khone Falls in southern Lao PDR. Furthermore, no consistent trends in the indices of relative abundance, biomass or species richness were observed among the 10 fisher catch monitoring locations that have been monitored between 2003 and 2010. However, relative fish biomass at many monitoring locations in the basin including the dai fishery, and reproductive success indicated by the recruitment index (RI) monitored at Phnom Penh, Cambodia for species with a drifting larval stage, appeared to be relatively low after 2005–06 compared to previous years. Since June 2005, few C. lobatus and H. siamensis were reported upstream of the Khone Falls. Moreover, their relative biomass and particularly that of P. proctozystron also appears to have declined significantly through time, notably at Pres Bang (Sekong River). It remains uncertain whether these trends reflect real declines in stock abundance or behavioral change. These differences were less evident for the larger cyprinid and pangasiid species examined suggesting that recent rates of recruitment in the small cyprinid populations may have been influential rather that local environmental factors. It remains to be seen whether fish biomass in the system will recover to previous levels.

Therefore, whilst "absence of proof is not proof of absence" (Hortle et al., 2004: 9), and assuming overall levels of fishing effort have remained relatively unchanging, the assertion that the diversity and abundance of the multispecies assemblage has declined significantly in the basin would appear to remain contentious. Even populations of some species that are included on the IUCN list of


Page 96

endangered species that seasonally utilize the TS-GL system in Cambodia have shown no apparent decline in relative biomass indicated by the dai fishery catch rates (Figure 51). These conclusions appear consistent with those drawn by MRC (2010); Baird and Flaherty (2004).

Populations of the largest species in the basin (e.g. Pangasianodon gigas) are particularly vulnerable to over-exploitation. These species are not the target of the fisheries examined here but, are sometimes caught incidentally in small numbers. However, having declined in size in response to over-exploitation by a targeted fishery during the late 1980’s, the population of P. gigas species has recently showed signs of recovery (Lorenzen et al., 2006).

Most species examined appear to exhibit life cycles and migrations that are largely consistent with the general life cycle model described in Section 6.1. Migrations of some species including C. lobatus and H. siamensis, P. proctozystron, P. malcolmi, C. harmandi, P. conchophilus and P. pleurotaenia appear to extend long distances upstream, at least as far as Luang Prabang. At least for C. lobatus and H. siamensis this was supported by positive correlations between catches rates observed in the dai and lee trap fisheries and between larvae density estimates at Phnom Penh and catch rates observed in the lee trap fishery. Labeo chrysophekadion was particularly abundant in northern Cambodia and northern Lao PDR possibly indicating the presence of two stocks.

The migrations of other species such as C. microlepis, P. larnaudii appeared less extensive and Hemibagrus nemurus was reported only in Lao PDR, suggesting that it undertakes only limited migrations. Y. modesta whilst abundant in the Tonle Sap appears to be less migratory than previously believed (e.g. Halls and Kshatriya 2009; Poulsen et al., 2004).

0

1

10

100

1000

10000

97-98 99-00 01-02 03-04 05-06 07-08 09-10

Season

ln C

PUE

(kg/

dai/s

easo

n)

Catlocarpio siamensisPangasius sanitwongseiProbarbus jullieniProbarbus labeamajor

Figure 51 Relative biomass of some important Mekong species on the IUCN list of endangered species

indicated by dai fishery catch rates.

Whilst fish migrations from the TS-GL system appear to be strongly linked to the lunar cycle as suggested by earlier workers (Baird et al., 2003), a similar response was not evident at the lee trap fishery in southern Lao PDR for the multi-species assemblage. Rather the rise in water level appears to stimulate the migrations of non-pangasiid species. The converse appears to exist for pangasiid species that appear to be caught in larger quantities at lower flows. Using catch observations over relatively short periods of the rising water phase combined with local ecological knowledge, Baird et al. (2004) also concluded that the migrations of P. conchophilus at the Falls were not correlated with lunar cycles. However, contrary to the findings presented here, they also concluded that the migrations of pangasiid species respond positively to rising water levels. Further investigations appear necessary to confirm or reject the existence of these responses.

Statistical attempts to identify spawning locations in the LMB were largely unsuccessful. However, visual examination of the spatial and temporal variation in fisher catch rates suggested that Stung Treng province, Cambodia and the three tributaries in the Sesan basin appear to be important spawning locations for small cyprinids. The Srepok River also appears to provide important habitat for medium and large species of cyprinid: Labeo chrysophekadion, Poropuntius malcolmi and Cosmochilus harmandi. The Sesan and Sekong rivers also appear to provide important habitat for Pangasiid catfish. However, unlike for cyprinids, the Srepok appears relatively unimportant for all three species examined and P. conchophilus was not reported at Banfang (Sekong River). Age distributions of larvae sampled at Phnom Penh combined with estimates of drift rates also placed spawning locations in the vicinity of, or above, the Khone falls for Henicorhynchus and pangasiid species.

The abundance and biomass of the multispecies assemblage that seasonally utilizes the TS-GL system responds significantly to the transport of larvae from upstream spawning locations. The growth experienced by these larvae and their parents appears to be dependent upon the spatial and temporal availability of food resources in the system determined by flooding extent and duration as indicated by the flood index (FI). The flood index explains much of the observed variation in the indices of the biomass of fish migrating from the system each year to dry season refuge habitat as indicated by the catch rates observed for the dai fishery in the Tonle Sap. Relative fish biomass in the system was exceptionally high during the 2004–05 and 2005–06 fishing seasons. It is likely that very high levels of recruitment were responsible for this variation since growth rates were as expected for the FI. In 2004 larvae were mostly Henicorhynchus species but, in 2005 larvae from other species were also transported into the system in abundance.

It has been shown that the estimated annual fluxes of larvae (recruits) to the system could comfortably support the dai fishery even assuming that 90 % of the recruits were caught in the TS-GL system by other fisheries and if the average larvae survival rate each season was less than 10 %.

The estimated response of fish biomass to larvae transport suggests that larvae survival (mortality) may be density-dependent. Density-dependent mortality (DDM) could be a consequence of competition for food leading to starvation or increased predation. Fish with reduced growth rates are exposed to predators for a longer time or fish may have to spend more time feeding and moving which may increase exposure to predators (Myers and Cadigan, 1993).

Conclusions and Recommendations


Page 98

The transport of larvae to the system indicated by the recruitment index (RI) may provide a simple predictor of dai catch rates because it encapsulates the effects of both larvae transport (a function of flow and larvae density) on fish recruitment (abundance) and flooding extent (a function of flow) on fish growth.

What factors might be responsible for high rates of recruitment observed in 2004 and 2005? Recruitment to the system is likely to be dependent upon the biomass of the spawning stock, spawning success, larvae survival after hatching, and rates of transport.

Reducing rates of exploitation and allowing fish to grow to maturity are often primary goals of fishery managers in their attempts to increase spawning stock biomass and thereby recruitment. It was therefore disappointing that the significant efforts made by the FiA to confiscate illegal gear in the TS-GL system had apparently no detectable effect on the relative biomass of fish migrating from the system each year–an index of next year’s spawning stock biomass. Exceptionally high rates of recruitment may have over-shadowed the effects of these management efforts to the extent that they were undetectable. Experimentation may be necessary to confirm the effects of gear confiscations, perhaps in the context of more adaptive management approaches (Hilborn and Walters, 1992). However, it is noted that the confiscation of more than 1,000 km of fine mesh fence in 2008 had no discernible benefits for recruitment or dai catch rates.

Even if gear confiscations had a detectable effect on spawning stock size, it remains uncertain if it would have benefited recruitment because the high rates of recruitment estimated in 2004 and 2005 were apparently produced by only small to above average-size spawning stock sizes assuming that the dai fishery provides a reliable index of spawning stock biomass. Moreover, no obvious relationship was found between this index of spawning stock biomass each year and the subsequent index of recruitment back into the system. These high rates of recruitment were therefore probably the result of favourable conditions for spawning, and larvae survival or transport, or for a combination thereof.

The rate at which water levels rose and flowed into the system were relatively high in 2005, and second only to the rates observed in 2002. This may have stimulated upstream spawning migrations and benefited larvae survival and transport. It is noteworthy that the relative biomass of 9 of the 14 species monitored at the lee trap fishery, which targets the spawning migrations of fish, also peaked in 2005. Relative stock size during the spawning period (June–September) at the majority of fisher catch monitoring locations in 2004 and 2005 also appeared to be among the highest recorded. Fish larvae may also have been exposed to predation for a shorter period of time and would be more likely to arrive at downstream food resources before exhausting their yolk sacs. However, reasons for the very high rates of recruitment estimated for Henicorhynchus species in 2004 remain perplexing. A closer examination of hydrological and water quality parameters across the geographic range of these species and particularly during the spawning season at likely spawning locations, including the Sesan basin, appears warranted. This exploration of potential environmental influences might also help to explain why recruitment was also relatively successful for many species in 2008.

Given its apparent importance for cyprinids and pangasiid catfish that make significant contributions to the yield from the LMB, greater consideration might be given to conserving tributary habitat during basin development planning in the future. More research is also needed to understand the role of tributaries in the LMB in the lifecycles of important species.

Attempts to identify the location of spawning sites, the extent of fish migrations and hydrological influences on fish stocks were hampered by the imprecise estimates of fish abundance, biomass and mean weight at the fisher catch monitoring locations, and larvae density at the monitoring locations in Cambodia. Lack of variation in the flood index over the period examined also hampered the detection of hydrological influences. For selected species, a power analysis (Zar, 1984) would help guide future target sample sizes at these monitoring locations to detect acceptable minimum detectable differences for management performance evaluation and impact assessment purposes.

To improve the accuracy of estimates of the relative biomass of fish migrating through the channel each year, it is recommended that monitoring should be undertaken throughout the period when traps are active, possibly between as early as April to as late as October. If resources permit, attempts should also be made to estimate the total number of traps operating at the falls each year, including those downstream of the monitoring site since these will also affect (upstream) catch rates in the HSY channel and may help to explain variation in spawning or recruitment success.

The fisher catch monitoring programmes provide a cost-effective means by which to monitor the status and trends of fisheries resources in the basin. In addition to performing the power analysis described above, the standardization of databases including their structure, field names, queries and reports would greatly benefit future integrated analyses of the data generated by this monitoring programme. Consideration might also be given to adopting standard ‘look-up tables’ for species, gears and habitats, greater automated error checking in data entry forms and user restrictions on what entries and changes can be made.

Recruitment in the system appears to be an overwhelming factor affecting the dynamics of fish stocks in the LMB. Sustaining larvae monitoring programmes will therefore be necessary to monitor and interpret trends in fisheries resources in the future. Monitoring larvae density and flows into the TS-GL system may also provide a simple basis with which to predict dai fishery yield and catch rates.

Sampling procedures adopted by the larvae monitoring programme in Viet Nam should be reviewed and possibly standardized with those used at the Cambodian monitoring location to allow for valid comparisons between the two locations. The integrity, accuracy and utility of the existing data require careful checking and scrutiny. Database queries should be written to estimate larvae density and annual recruitment indices within the database accounting for changes to sampling methods including bongo net diameter which changed from 0.5 m to 1.0 m after 2003. These activities are regarded as priorities since recruitment appears to be the main source of variation in the multi-species assemblage and landings in the basin. Any additional sources of data and information concerning recruitment in the basin should therefore be considered. Whilst it currently appears sound and well

Conclusions and Recommendations


Page 100

managed, it is also recommended that a standard set of queries be prepared for the Cambodian larvae monitoring programme database thereby avoiding the need for cumbersome external spreadsheet calculations.

Finally, it is recommended that manuals be prepared for the databases developed for each of the four monitoring programmes describing the details of their content (including field descriptions and units of measurement), structure, and all calculations performed by data entry forms, queries and reports.

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Baird, I.G.; Flaherty, M.S. and Phylavanh, B. (2003). Rhythms Of The River: Lunar Phases and Migrations of Small Carps (Cyprinidae) In The Mekong River. Nat. Hist. Bull. Siam Soc, 51(1): 5-36.

Baran, E. (2005). Cambodian Inland Fisheries. Facts, figures and context. WorldFish Center and Inland Fisheries and Development Institute, Phnom Penh, Cambodia, 49pp.

Baran, E.; Baird, I.G. and Cans, G. (2005). Fisheries bioecology at the Khone Falls (Mekong River, southern Laos). World Fish Center, 84pp.

Baran, E.; Van Zalinge, N. and Ngor, P.B. (2001). Analysis of the Cambodian Bagnet "Dai" fishery data. ICLARM, Penang, Malaysia, Mekong River Commission Secretariat and Department of Fisheries, Phnom Penh, Cambodia, Penang, Malaysia, 50pp.

Chevey, P. and Le Poulain, F. (1940). La pêche dans les eaux douces du Cambodge 5e mémoire. Travaux de L'Institut Océanographique de L'Indochine, 195pp.

Chomchanta, P.; Vongphasouk, P.; Soukhaseum, V.; Soulignavong, C.; Saadsy, B. and T.J. Warren (2000). Migration studies and CPUE data collection in southern Lao PDR. 1994–2000. Mid-Project Summary Report. Prepared for: The Living Aquatic Resources and Research Center (LARReC), Vientiane, Lao PDR, 25pp.

Doan, V.T.; Lam, N.C.; Mai, T.T.C. and K.G. Hortle (2006). Trial monitoring of fishers in the Mekong Delta Viet Nam. In: (Burnhill, T.J. and T.J. Warren eds.) Proceedings of the 7th Technical Symposium on Mekong Fisheries, Ubon Ratchathani, 15th – 17th November 2005: 61-70.

Fily, M. and d'Aubenton, F. (1965). Cambodge - Grand Lac Tonle Sap - Technologie des Pêches 1962-1963. République Française, Minisţère des Affaires Etrangères, service de coopération technique.

Froese, R. and Pauly, D. Editors (2010). FishBase. World Wide Web electronic publication. www.fishbase.org, version (05/2010).


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Gotelli, N.J. and Colwell, R.K. (2001). Quantifying biodiversity: procedures and pitfalls in the measurement and comparison of species richness. Ecology Letters, 4: 379-391.

Halls, A.S. et al. (in preparation). Deep pools as dry season fish habitat in the lower Mekong basin – a quantitative assessment.

Halls, A.S.; Paxton, B.R.; Hall, N.; Peng Bun, N.; Lieng, S.; Pengby, N.; and So, N (2013). The Stationary Trawl (Dai) Fishery of the Tonle Sap-Great Lake, Cambodia. MRC Technical Paper No. 32, Mekong River Commission, Phnom Penh, Cambodia, 142pp.

Halls, A.S. & Paxton, B.R. (2012). The Stationary Trawl (Dai) Fishery of the Tonle Sap-Great Lake System, Cambodia. In: R. Welcomme, J. Valbo-Jorgensen & A.S. Halls (eds.) Inland fisheries evolution and management – case studies from four continents. FAO Fisheries and Aquaculture Technical Paper, 579, Rome: FAO.

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Ann

ex

Tabl

e 19

Stat

istic

s of c

onfis

catio

n an

d de

stru

ctio

n of

ille

gal fi

shin

g ge

ars (

2000

to 2

009)

.

No

Item

sU

nit

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

1Fi

ne m

esh

net f

ence

m4,

000

1,0

92,9

41

1,7

56,0

35

447

,402

6

72,2

07

467

,821

1

,096

,570

1

,188

,249

2

Fine

mes

h ne

t cyl

indr

ical

trap

Uni

ts 2

5 4

1 2

3,93

1 2

1,71

4 1

1,28

7 1

7,43

5 9

,951

6

,673

4

,019

3

Boa

tsU

nits

20

1

4D

ai ta

rget

cat

fish

fry

Cod

end

Uni

ts 6

3 5

5

Bam

boo

fenc

em

324

,015

9

9,39

6 4

0,78

8 5

1,67

8 6

Bru

sh p

ark

Uni

ts 5

2,56

5 7

6,80

5 9

1,38

8 1

9,42

0 7

Fine

mes

h se

ine

Uni

ts 1

6

1

28

1,6

10

3,5

68

3,6

20

33

84

2

8D

ai tr

ey p

ra m

sao

(cap

ture

smal

l fr

y of

pan

gasi

us sp

p.)

Uni

ts 9

9 1

3 2

8 1

06

125

6

1 1

9

9D

ai T

rey

linh

(thyn

nicg

thys

th

ynno

ides

)U

nits

22

9

5

141

4

7 1

38

163

10U

on o

s (se

ine)

Uni

ts 1

8

4 9

2 3

3 11

Uy

tow

ed b

y en

gine

(mos

quito

net

to

wed

by

engi

ne to

cap

ture

smal

l fis

h)

units

5

12Ex

plos

ive

Uni

ts13

Pois

onU

nits

14C

hhib

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wl w

ith e

ngin

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mar

ine)

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t 7

5

8 3

7

15Pa

ir tra

wle

rsU

nits

3

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shin

g in

the

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n ar

eaU

nits

17El

ectro

fish

ing

Uni

ts 1

1

6 5

,684

7

,364

1

1,51

6 1

1,98

6 1

,075

5

,312

18

Han

dle

for e

lect

rofis

hing

U

nits

2

19En

gine

Uni

ts 1

1 20

Nor

rav

(Arr

ow sh

ape

trap)

Uni

ts 1

5,43

5 3

65

21Po

le fo

r bam

boo

fenc

eU

nits

200

2

64,7

38

166

,390

1

77,5

26

293

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22

Rel

ease

of s

mal

l fish

, m

ixed

spec

ies

Pcs.

320,

720,

354

41,

149,

500

36,

485,

345

112,

482,

000

292,

356,

840

11,

741,

950

1,6

51,0

00

Kg

& 5

4856

&

444

50

24C

onfis

cate

d tra

ctor

Uni

ts7

10

Sour

ce: F

iA, C

ambo

dia

Annex


Page 106

Table 20 Percentage contributions of fish species to total catch weight reported under the fisher catch monitoring programmes, all gears and habitats.

CAMBODIA LAO PDR THAILAND VIET NAM

Species AMCF FEVM AMCF FEVM AMCF FEVM AMCF FEVM Average % Count

Henicorhynchus siamensis 13.2 1.2 12.3 0.8 2.1 7.0 3.6 6.7 5.9 8Clupeoides borneensis 0.0 17.0 0.0 5.7 3Cosmochilus harmandi 1.4 2.7 9.5 8.7 6.5 6.2 0.0 0.1 4.4 8Labeo chrysophekadion 3.5 3.6 11.5 3.7 6.7 1.7 1.6 0.6 4.1 8Cirrhinus lobatus 6.5 4.6 12.8 0.1 0.7 1.1 0.5 0.9 3.4 8Hemibagrus spilopterus 8.2 2.9 0.4 0.9 3.3 6.8 0.8 3.3 7Pangasius conchophilus 1.6 2.4 6.3 8.4 2.7 4.5 0.4 0.1 3.3 8Hemibagrus nemurus 3.8 0.9 3.2 3.1 2.7 4Phalacronotus apogon 4.9 1.5 0.4 2.7 4.3 0.6 6.0 0.2 2.6 8Puntioplites falcifer 2.3 6.0 1.5 0.8 2.5 0.5 3.9 2.5 7Poropuntius malcolmi 3.9 7.6 1.0 0.9 4.1 1.9 0.0 0.0 2.4 8Anabas testudineus 0.4 0.8 0.0 1.6 0.3 2.1 10.7 2.3 7Helicophagus waandersii 2.6 4.5 0.8 5.4 0.1 0.0 2.2 6Wallago attu 1.7 0.1 2.7 0.2 0.2 0.2 11.9 0.0 2.1 8Barbonymus gonionotus 2.4 0.2 0.4 0.4 1.6 0.3 5.4 6.0 2.1 8Cyprinus carpio carpio 0.1 0.0 0.4 13.4 0.5 1.4 0.1 0.0 2.0 8Polynemus dubius 0.2 0.2 0.1 0.0 3.5 7.5 1.9 6Scaphognathops stejnegeri 0.9 2.2 1.1 6.2 2.1 0.1 0.0 1.8 7Nibea soldado 1.8 1.8 1Netuma thalassina 0.0 0.0 0.0 0.0 0.7 9.5 1.7 6Macrobrachium sp. 3.3 0.1 1.7 2Pangasius macronema 0.8 3.0 0.6 2.0 3.8 0.3 1.2 1.8 1.7 8Hemibagrus wyckioides 1.4 2.0 0.7 4.2 3.6 0.5 0.0 0.1 1.5 8Bagarius yarrelli 0.9 0.2 3.1 6.8 1.1 0.1 0.0 0.0 1.5 8Paralaubuca riveroi 2.5 0.5 1.5 2Helicophagus leptorhynchus 2.9 1.9 0.9 0.2 1.5 4Mystus mysticetus 0.5 0.1 0.1 0.0 0.9 0.6 3.1 6.1 1.4 8Puntioplites proctozystron 1.7 0.4 0.2 0.4 1.3 0.5 0.2 5.1 1.2 8Hypsibarbus lagleri 0.6 1.4 0.2 5.1 1.8 0.5 0.0 0.0 1.2 8Macrognathus siamensis 0.1 0.1 0.0 0.1 0.0 2.1 5.6 1.1 7Bagarius bagarius 0.0 0.1 0.0 6.6 1.6 0.7 0.0 0.0 1.1 8Labiobarbus lineatus 2.2 0.0 0.4 0.0 1.0 0.1 3.2 1.7 1.1 8Notopterus notopterus 0.2 0.7 0.0 0.0 0.7 3.7 2.5 0.3 1.0 8Pangasius djambal 0.0 0.0 4.1 2.0 0.0 0.0 1.0 6Labeo erythropterus 1.9 0.1 1.0 2Channa striata 1.4 2.0 0.2 0.0 0.9 0.9 2.2 0.4 1.0 8Boesemania microlepis 0.7 0.7 0.0 1.0 2.5 1.0 5Phalacronotus bleekeri 1.7 3.3 0.5 1.3 0.2 0.4 0.0 0.2 1.0 8Syncrossus helodes 0.1 0.3 0.4 0.0 6.1 0.0 0.6 0.0 1.0 8Hemibagrus filamentus 0.6 1.4 1.8 0.0 0.9 4


Coilia macrognathos 0.0 0.5 2.1 0.9 3Arius maculatus 0.0 0.0 0.0 0.0 0.1 5.0 0.9 6Probarbus jullieni 0.4 0.2 0.2 3.3 2.2 0.2 0.0 0.0 0.8 8Paralaubuca typus 1.4 0.6 1.3 0.0 0.4 0.2 2.4 0.1 0.8 8Sikukia gudgeri 0.0 1.6 0.8 2Syncrossus beauforti 0.0 1.5 0.8 2Mystus singaringan 2.0 0.2 0.1 0.5 0.3 1.4 0.8 0.7 7Thynnichthys thynnoides 0.6 0.6 0.3 3.0 0.0 0.0 0.7 6Cyclocheilichthys enoplus 2.0 1.4 0.1 0.1 0.6 0.2 1.1 0.4 0.7 8Puntius spilopterus 1.5 0.0 0.7 2Pangasius krempfi 0.4 0.1 1.0 1.3 0.1 0.1 0.3 2.7 0.7 8Gyrinocheilus pennocki 3.7 0.4 0.2 0.0 0.0 0.0 0.7 6Hypsibarbus wetmorei 0.4 0.9 0.7 2.0 1.3 0.1 0.0 0.0 0.7 8Rasbora daniconius 0.7 0.7 1Coilia lindmani 0.0 0.0 2.0 0.7 3Osteogeneiosus militaris 0.0 0.0 2.0 0.7 3Osteochilus vittatus 0.2 1.5 0.1 0.6 3Cyclocheilichthys armatus 0.7 1.1 0.0 0.0 0.8 2.0 0.0 0.1 0.6 8Belodontichthys truncatus 0.9 1.3 0.5 0.0 0.4 0.6 1.0 0.0 0.6 8Yasuhikotakia modesta 0.2 1.4 0.1 0.1 0.4 1.8 0.4 0.1 0.6 8Cirrhinus microlepis 2.1 0.8 0.1 0.1 1.1 0.0 0.2 0.0 0.5 8Acanthopsis sp.5 0.0 0.0 0.0 3.2 0.0 0.0 0.5 6Ompok bimaculatus 0.1 0.2 0.0 0.3 0.5 1.9 0.6 0.5 7Pangasius elongatus 0.2 0.5 0.1 0.2 0.1 0.0 0.8 2.2 0.5 8Hampala macrolepidota 0.3 0.4 0.2 0.1 0.1 0.0 2.8 0.2 0.5 8Labiobarbus siamensis 0.5 2.2 0.1 0.4 0.0 0.3 0.0 0.5 7Hypsibarbus vernayi 0.9 0.0 0.1 1.3 1.2 0.0 0.0 0.5 7Cyclocheilichthys furcatus 0.4 0.4 0.4 0.1 1.9 0.1 0.0 0.7 0.5 8Yasuhikotakia eos 0.1 0.9 0.5 2Cynoglossus microlepis 0.1 0.2 0.0 2.0 0.2 0.5 5Hypostomus plecostomus 0.0 0.9 0.5 2Pristolepis fasciata 0.1 0.8 0.0 0.0 0.5 0.5 1.3 0.5 0.5 8Channa marulioides 0.3 0.6 0.5 2Pangasius larnaudii 0.6 1.1 0.1 0.0 0.1 1.1 0.2 0.5 7Pangasius pleurotaenia 0.1 0.4 0.1 0.2 1.0 0.2 0.0 1.6 0.5 8Hypsibarbus pierrei 0.9 0.0 0.4 2Chitala ornata 0.2 0.1 0.1 0.8 0.3 1.9 0.0 0.0 0.4 8Puntius brevis 0.0 0.0 0.0 1.7 0.4 4Chitala blanci 0.8 1.6 0.0 0.1 0.1 0.0 0.4 6Cirrhinus cirrhosus 0.0 0.0 0.2 0.3 0.2 2.5 0.0 0.0 0.4 8Barbonymus altus 0.6 0.2 0.6 0.3 1.1 0.3 0.1 0.0 0.4 8Phalacronotus micronemus 0.5 0.3 0.4 2Pseudapocryptes elongatus 0.4 0.4 1

Annex


Page 108


Labeo dyocheilus 0.8 0.8 0.4 0.5 0.5 0.0 0.0 0.0 0.4 8Parambassis siamensis 0.0 0.0 1.8 0.0 0.0 0.4 5Clarias batrachus 0.2 0.7 0.0 0.1 0.4 0.2 1.1 0.1 0.4 8Osteochilus hasseltii 0.1 0.6 0.0 0.0 1.1 0.2 0.3 6Hypophthalmichthys molitrix 0.2 0.0 0.1 0.0 0.0 2.2 0.2 0.1 0.3 8Parachela siamensis 0.3 0.3 1Argyrosomus sp. 0.3 0.3 1Pangasius bocourti 0.1 0.3 0.3 0.5 0.5 0.6 0.2 0.1 0.3 8Clarias macrocephalus 0.1 0.4 0.0 0.2 0.0 1.4 0.1 0.3 7Hemiarius stormii 0.3 0.3 1Cyclocheilichthys repasson 0.6 0.6 0.1 0.0 0.9 0.2 0.0 0.0 0.3 8Trichogaster trichopterus 0.1 0.1 0.0 0.1 0.1 0.3 1.5 0.3 7Luciosoma bleekeri 0.1 0.2 0.0 0.8 0.0 0.9 0.0 0.3 7Yasuhikotakia lecontei 0.0 0.6 0.3 2Hampala dispar 0.1 1.0 0.1 0.0 1.0 0.0 0.0 0.0 0.3 8Scaphognathops bandanensis 0.1 0.3 0.3 0.1 1.0 0.0 0.1 0.3 7Labiobarbus leptocheila 0.0 0.5 0.3 2Probarbus labeamajor 0.2 0.1 0.2 0.0 1.4 0.2 0.0 0.0 0.3 8Hypsibarbus suvattii 0.3 0.3 1Hemisilurus mekongensis 0.2 0.8 0.2 0.6 0.1 0.3 0.0 0.0 0.3 8Amblyrhynchichthys micracanthus

0.2 0.9 0.2 0.3 0.1 0.0 0.3 0.0 0.3 8

Bagarius suchus 0.1 0.4 1.0 0.1 0.2 0.0 0.0 0.3 7Kryptopterus cheveyi 0.1 0.6 0.8 0.1 0.2 0.1 0.1 0.0 0.3 8Parambassis wolffii 0.2 0.6 0.0 0.2 0.3 0.3 5Rasbora tornieri 0.4 0.3 0.0 0.3 3Cyclocheilichthys lagleri 0.3 0.3 1Pangasius spp. 0.3 0.3 1Mastacembelus armatus 0.4 0.6 0.1 0.0 0.0 0.1 0.7 0.1 0.2 8Acanthopsis sp.2 0.2 0.2 1Mystus atrifasciatus 0.1 0.4 0.2 2Yasuhikotakia sp. cf. lecontei 0.0 0.0 0.0 1.6 0.0 0.1 0.0 0.2 7Mekongina erythrospila 0.6 0.2 0.2 0.6 0.1 0.0 0.0 0.2 7Glossogobius giuris 0.0 0.0 0.9 0.0 0.2 4Cirrhinus molitorella 0.1 0.1 1.0 0.4 0.1 0.0 0.0 0.0 0.2 8Bangana behri 0.5 0.2 0.2 0.1 0.5 0.1 0.0 0.2 7Puntius orphoides 0.1 0.5 0.0 0.0 0.0 0.6 0.2 6Osteochilus melanopleurus 0.4 0.6 0.0 0.0 0.2 0.1 0.1 0.3 0.2 8Osphronemus exodon 0.5 0.5 0.0 0.0 0.0 0.2 5Pangasianodon hypophthalmus 0.4 0.2 0.0 0.0 0.0 0.1 0.5 0.2 0.2 8Belodontichthys dinema 0.3 0.1 0.2 2Oxyeleotris marmorata 0.1 0.2 0.0 0.1 0.2 0.8 0.0 0.0 0.2 8Pangasius mekongensis 0.0 0.4 0.2 2


Labeo rohita 0.0 0.1 0.0 0.1 0.2 0.6 0.6 0.0 0.2 8Wallago micropogon 0.3 0.2 0.0 0.2 0.5 0.0 0.0 0.2 7Lobocheilos melanotaenia 0.2 0.7 0.1 0.0 0.0 0.3 0.0 0.0 0.2 8Brachirus orientalis 0.1 0.5 0.0 0.0 0.0 0.4 0.2 0.2 7Barbonymus schwanenfeldii 0.2 1.0 0.1 0.0 0.1 0.0 0.0 0.0 0.2 8Bagrichthys obscurus 0.4 0.7 0.0 0.1 0.0 0.0 0.0 0.0 0.2 8Mystacoleucus greenwayi 0.0 0.3 0.2 2Channa micropeltes 0.3 0.3 0.1 0.3 0.0 0.0 0.2 6Xenentodon cancila 0.0 0.1 0.0 0.0 0.3 0.7 0.0 0.2 7Dasyatis laosensis 0.1 0.0 0.0 0.5 0.3 0.0 0.0 0.2 7Osteochilus lini 0.0 0.0 0.5 0.2 0.0 0.2 0.1 6Pseudomystus siamensis 0.2 0.4 0.0 0.0 0.2 0.1 5Rasbora septentrionalis 0.0 0.3 0.1 2Betta smaragdina 0.1 0.1 1Clupeichthys aesarnensis 0.1 0.0 0.0 0.1 0.7 0.0 0.1 6Macrochirichthys macrochirus 0.7 0.1 0.0 0.0 0.2 0.0 0.0 0.1 7Cirrhinus jullieni 0.1 0.2 0.3 0.2 0.0 0.2 0.0 0.1 7Probarbus labeaminor 0.3 0.0 0.1 2Clupisoma sinense 0.0 0.2 0.2 0.1 0.1 0.2 0.2 0.1 0.1 8Glossogobius aureus 0.1 0.1 0.1 2Pseudolais micronemus 0.2 0.2 0.1 0.0 0.0 0.3 0.1 6Cyclocheilichthys apogon 0.2 0.1 0.1 2Monopterus albus 0.0 0.1 0.1 0.1 0.5 0.1 0.0 0.1 7Mystus bocourti 0.3 0.5 0.0 0.0 0.0 0.2 0.0 0.0 0.1 8Bagrichthys majusculus 0.4 0.0 0.0 0.1 3Osphronemus goramy 0.1 0.4 0.0 0.1 0.0 0.1 5Leiognathus sp. 0.1 0.1 1Oreochromis niloticus 0.0 0.0 0.0 0.0 0.3 0.3 0.0 0.3 0.1 8Hemibagrus wyckii 0.2 0.3 0.1 0.0 0.0 0.1 0.2 0.0 0.1 8Kryptopterus limpok 0.1 0.1 1Clarias gariepinus 0.2 0.0 0.1 0.0 0.0 0.0 0.4 0.1 0.1 8Plotosus canius 0.0 0.0 0.0 0.3 0.2 0.1 5Bangana sp. 0.4 0.0 0.0 0.1 0.2 0.0 0.0 0.1 7Colossoma macropomum 0.0 0.2 0.1 2Heteropneustes kemratensis 0.1 0.1 1Parapocryptes serperaster 0.1 0.1 1Barbichthys nitidus 0.0 0.0 0.0 0.6 0.0 0.0 0.1 6Harpadon nehereus 0.0 0.2 0.1 2Yasuhikotakia morleti 0.0 0.2 0.1 2Hemiarius verrucosus 0.3 0.0 0.0 0.0 0.0 0.0 0.3 0.1 7Raiamas guttatus 0.2 0.1 0.1 0.2 0.1 0.0 0.0 0.1 7Parachela williaminae 0.1 0.1 1Paralaubuca barroni 0.2 0.0 0.1 2

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Channa melasoma 0.1 0.1 0.4 0.0 0.0 0.0 0.1 6Mystus albolineatus 0.0 0.2 0.2 0.0 0.1 4Eleotris fusca 0.2 0.0 0.1 2Mixed species Thai Catch 0.1 0.1 1Don't Know 0.2 0.0 0.1 2Datnioides undecimradiatus 0.1 0.3 0.0 0.0 0.0 0.0 0.1 0.1 7Poropuntius deauratus 0.1 0.0 0.1 0.3 0.0 0.0 0.0 0.1 7Mystus multiradiatus 0.0 0.2 0.0 0.1 3Leptobarbus hoevenii 0.1 0.2 0.0 0.2 0.0 0.0 0.1 6Bagrichthys macropterus 0.1 0.1 1Yasuhikotakia caudipunctata 0.0 0.1 0.1 2Acanthopsis sp.1 0.1 0.0 0.0 0.1 0.2 0.1 5Osteochilus schlegelii 0.1 0.0 0.0 0.3 0.0 0.1 0.0 0.1 7Pangasius pangasius 0.2 0.0 0.0 0.1 3Chitala lopis 0.1 0.2 0.0 0.0 0.1 0.0 0.0 0.1 7Garra cambodgiensis 0.1 0.1 1Boleophthalmus boddarti 0.1 0.1 1Lycothrissa crocodilus 0.0 0.2 0.0 0.0 0.0 0.0 0.1 0.1 7Arius venosus 0.1 0.1 1Pangasianodon gigas 0.0 0.0 0.0 0.2 0.2 0.0 0.0 0.1 7Mystus gulio 0.0 0.1 0.1 2Kryptopterus geminus 0.1 0.1 0.0 0.0 0.2 0.0 0.1 0.0 0.1 8Channa gachua 0.0 0.2 0.0 0.0 0.0 0.1 5Macrobrachium rosenbergii 0.1 0.1 1Cyclocheilichthys heteronema 0.1 0.0 0.1 2Rasbora borapetensis 0.0 0.0 0.0 0.2 0.0 0.1 5Hyporhamphus limbatus 0.0 0.0 0.0 0.0 0.0 0.3 0.0 6Garra fasciacauda 0.0 0.0 0.0 0.2 0.0 0.0 0.0 6Rasbora trilineata 0.0 0.0 0.0 0.0 0.2 0.0 0.0 6Tor tambroides 0.0 0.0 0.0 0.1 0.0 4Tenualosa thibaudeaui 0.1 0.0 0.1 0.0 0.1 0.0 0.0 0.0 7Kryptopterus schilbeides 0.0 0.0 1Kryptopterus palembangensis 0.0 0.0 1Laides longibarbis 0.0 0.1 0.1 0.0 0.0 0.0 5Laides hexanema 0.1 0.0 0.0 2Tor laterivittatus 0.0 0.0 0.0 0.1 0.0 4Liza vaigiensis 0.0 0.1 0.0 0.0 3Oryzias minutillus 0.0 0.0 1Puntioplites bulu 0.0 0.2 0.0 0.0 0.0 0.0 5Polynemus melanochir 0.0 0.0 1Puntius binotatus 0.0 0.0 0.0 2Mugil cephalus 0.0 0.0 0.0 0.2 0.0 0.0 5Glossogobius sparsipapillus 0.0 0.0 1


Puntius rhombeus 0.1 0.0 0.0 0.1 0.0 0.0 5Rasbora myersi 0.0 0.0 0.0 2Arius sp. 0.0 0.1 0.0 2Tor sinensis 0.0 0.0 0.0 0.1 0.0 0.0 5Batrachomoeus trispinosus 0.0 0.1 0.0 2Catlocarpio siamensis 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 7Ctenopharyngodon idella 0.0 0.0 1Yasuhikotakia longidorsalis 0.0 0.0 1Scleropages formosus 0.0 0.1 0.0 2Mystus wolffii 0.0 0.0 1Albulichthys albuloides 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.0 7Paralaubuca harmandi 0.0 0.0 0.0 2Macrognathus circumcinctus 0.0 0.0 0.0 0.0 0.1 0.0 0.0 6Coilia dussumieri 0.0 0.0 0.0 2Brachirus harmandi 0.0 0.0 0.0 0.0 0.1 0.0 0.0 6Rasbora hobelmani 0.0 0.0 1Pangasius sanitwongsei 0.0 0.0 0.1 0.0 0.0 4Achiroides melanorhynchus 0.0 0.0 1Osteochilus microcephalus 0.1 0.1 0.0 0.0 0.0 0.0 0.0 6Corica soborna 0.0 0.0 1Rasbora aurotaenia 0.0 0.0 0.0 0.0 3Trichogaster microlepis 0.0 0.0 0.0 0.0 3Crossocheilus atrilimes 0.0 0.0 0.1 0.0 0.0 0.0 0.0 6Labiobarbus sp. cf. lineatus 0.0 0.0 0.0 0.0 0.0 0.0 5Piaractus brachypomus 0.0 0.0 1Trypauchen vagina 0.0 0.0 1Tetraodon barbatus 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6Allenbatrachus grunniens 0.0 0.0 1Ketengus typus 0.0 0.0 1Aaptosyax grypus 0.0 0.0 0.0 0.1 0.0 4Kryptopterus bicirrhis 0.0 0.0 0.1 0.0 0.0 0.0 0.0 6Nuchequula blochii 0.0 0.0 1Anguilla marmorata 0.0 0.0 0.0 0.1 0.0 0.0 0.0 6Mussels 0.0 0.0 1Gobiopterus brachypterus 0.0 0.0 0.0 2Dasyatis zugei 0.0 0.0 1Acanthopsoides delphax 0.1 0.0 0.0 0.0 0.0 4Hypophthalmichthys nobilis 0.1 0.0 0.0 0.0 0.0 0.0 5Tor ater 0.0 0.0 1Corica laciniata 0.0 0.0 0.0 2Lates calcarifer 0.0 0.0 0.0 0.0 3Oxyeleotris siamensis 0.0 0.0 1Butis butis 0.0 0.0 1

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Toxotes microlepis 0.0 0.0 0.0 0.0 0.0 0.0 5Taenioides anguillaris 0.0 0.0 1Ophisternon bengalense 0.0 0.0 0.0 2Puntius jacobusboehlkei 0.0 0.0 1Trichogaster pectoralis 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7Osteochilus waandersii 0.0 0.0 0.0 0.0 0.0 0.0 5Botia spp. Thai Catch/Mkt 0.0 0.0 1Megalops cyprinoides 0.0 0.0 0.0 0.0 0.0 0.0 5Schistura procera 0.0 0.0 1Pseudobagarius similis 0.0 0.0 1Scatophagus argus 0.0 0.0 0.0 0.1 0.0 0.0 5Scomberomorus sp. 0.0 0.0 1Ambassis buruensis 0.0 0.0 1Saurida sp. 0.0 0.0 1Inimicus didactylus 0.0 0.0 1Pisodonophis boro 0.0 0.0 1Eleutheronema tetradactylum 0.0 0.0 0.0 2Ompok hypophthalmus 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6Pangasius sp. 0.0 0.0 0.0 0.0 3Esomus metallicus 0.0 0.0 0.0 0.0 0.0 4Congresox talabonoides 0.0 0.0 0.0 2Sikukia stejnegeri 0.0 0.0 1Tenualosa toli 0.0 0.0 0.0 0.0 0.0 4Gastropoda B 0.0 0.0 1Gobiidae sp3. 0.0 0.0 1Puntioplites waandersi 0.0 0.0 0.0 0.0 0.0 0.0 5Puntius partipentazona 0.0 0.0 1Mastacembelus favus 0.0 0.0 1Tor tambra 0.0 0.0 0.0 2Scomberomorus sinensis 0.0 0.0 0.0 0.0 3Tetraodon baileyi 0.0 0.0 1Muraenesox cinereus 0.0 0.0 0.0 2Acanthocobitis sp. cf. bilotorio 0.0 0.0 0.0 2Gymnothorax tile 0.0 0.0 1Parambassis apogonoides 0.0 0.0 0.0 2Longiculter siahi 0.0 0.0 0.0 2Trichopsis schalleri 0.0 0.0 1Macrognathus semiocellatus 0.0 0.0 0.0 2Cyprinidae spp. 0.0 0.0 1Stigmatogobius sadanundio 0.0 0.0 1Syncrossus sp. cf. beauforti 0.0 0.0 0.0 0.0 3Henicorhynchus ornatipinnis 0.0 0.0 0.0 2Setipinna melanochir 0.0 0.0 1


Channa lucius 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6Mystus micracanthus 0.0 0.0 0.0 2Chela laubuca 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7Mystacoleucus atridorsalis 0.0 0.0 0.0 2Cynoglossus feldmanni 0.0 0.0 1Channa marulia 0.0 0.0 0.0 0.0 0.0 0.0 0.0 6Bangana elegans 0.0 0.0 0.0 2Yasuhikotakia sidthimunki 0.0 0.0 0.0 0.0 3Mystacoleucus marginatus 0.0 0.0 0.0 0.0 3Homaloptera vulgaris 0.0 0.0 1Sphyrna lewini 0.0 0.0 1Neolissochilus blanci 0.0 0.0 0.0 0.0 0.0 4Puntius leiacanthus 0.0 0.0 1Discherodontus ashmeadi 0.0 0.0 0.0 0.0 0.0 0.0 5Clarias meladerma 0.0 0.0 0.0 2Macrognathus taeniagaster 0.0 0.0 1Platycephalus indicus 0.0 0.0 1Poecilia reticulata 0.0 0.0 1Nemapteryx caelata 0.0 0.0 0.0 0.0 3Plicofollis argyropleuron 0.0 0.0 1Netuma bilineata 0.0 0.0 1Carcharhinus leucas 0.0 0.0 1Luciocyprinus striolatus 0.0 0.0 0.0 0.0 0.0 0.0 5Misgurnus anguillicaudatus 0.0 0.0 1Acanthopsoides gracilentus 0.0 0.0 0.0 0.0 3Neolissochilus stracheyi 0.0 0.0 0.0 2Mystacoleucus chilopterus 0.0 0.0 0.0 0.0 3Snails 0.0 0.0 1Himantura imbricata 0.0 0.0 1Lepidocephalichthys hasselti 0.0 0.0 1Toxotes chatareus 0.0 0.0 0.0 0.0 0.0 4Lobocheilos gracilis 0.0 0.0 1Periophthalmodon schlosseri 0.0 0.0 1Cryptarius truncatus 0.0 0.0 1Yasuhikotakia splendida 0.0 0.0 1Laocypris hispida 0.0 0.0 1Sundasalanx mekongensis 0.0 0.0 1Rasbora paviana 0.0 0.0 0.0 0.0 3Oreochromis mossambicus 0.0 0.0 1Rice field crabs 0.0 0.0 0.0 2Onychostoma fusiforme 0.0 0.0 1Gobiidae sp1. 0.0 0.0 1Sphyraena sp. 0.0 0.0 1

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Tetraodon fluviatilis 0.0 0.0 1Poropuntius consternans 0.0 0.0 0.0 2Brachirus sp. 0.0 0.0 1Pseudomystus stenomus 0.0 0.0 1Crossocheilus reticulatus 0.0 0.0 0.0 2Lobocheilos quadrilineatus 0.0 0.0 1Rasbora pauciperforata 0.0 0.0 1Tetraodon leiurus 0.0 0.0 0.0 2Stolephorus commersonnii 0.0 0.0 1Metzia lineata 0.0 0.0 1Datnioides polota 0.0 0.0 0.0 2Anguilla bicolor 0.0 0.0 1Clupisoma longianalis 0.0 0.0 1Rastrelliger brachysoma 0.0 0.0 0.0 2Unknown species 0.0 0.0 1Platycephalus sp. 0.0 0.0 1Aquatic or semiaquatic birds 0.0 0.0 1Saurida undosquamis 0.0 0.0 1Clarias sp. 0.0 0.0 1Epalzeorhynchos frenatum 0.0 0.0 1Troglocyclocheilus khammouanensis

0.0 0.0 1

Sorsogona tuberculata 0.0 0.0 1Rasbora atridorsalis 0.0 0.0 1Achiroides leucorhynchos 0.0 0.0 1Butis gymnopomus 0.0 0.0 1Serpenticobitis zonata 0.0 0.0 1Clarias cataractus 0.0 0.0 0.0 0.0 3Nandus oxyrhynchus 0.0 0.0 0.0 2Trachurus sp. 0.0 0.0 1Gambusia affinis 0.0 0.0 0.0 0.0 3Hyporhamphus intermedius 0.0 0.0 1Redigobius balteatus 0.0 0.0 1Pangio myersi 0.0 0.0 1Pangasius nasutus 0.0 0.0 1Cosmochilus cardinalis 0.0 0.0 0.0 2Xenentodon canciloides 0.0 0.0 1Taenioides cirratus 0.0 0.0 1Schistura athos 0.0 0.0 1Tor polylepis 0.0 0.0 1Balitora tchangi 0.0 0.0 1Zenarchopterus clarus 0.0 0.0 1Cyclochelichthys sp. 0.0 0.0 1


Gobiidae sp2. 0.0 0.0 1Hemiarius sona 0.0 0.0 1Amblyceps mucronatum 0.0 0.0 1Lobocheilos davisi 0.0 0.0 1Adult frogs and toads 0.0 0.0 1Epalzeorhynchos munense 0.0 0.0 0.0 2Pareuchiloglanis gracilicau-data

0.0 0.0 1

Tetraodon cochinchinensis 0.0 0.0 1Mystus rhegma 0.0 0.0 1Chanos chanos 0.0 0.0 1Neodontobutis aurarmus 0.0 0.0 1Mahidolia mystacina 0.0 0.0 1Monodactylus argenteus 0.0 0.0 1Cynoglossus lingua 0.0 0.0 0.0 2Trichopsis vittata 0.0 0.0 1Helostoma temminkii 0.0 0.0 1Salt crab 0.0 0.0 1Hexanematichthys sagor 0.0 0.0 0.0 2Lutjanus johnii 0.0 0.0 1Macrognathus maculatus 0.0 0.0 1Coilia rebentischii 0.0 0.0 1Carangoides armatus 0.0 0.0 1Strongylura incisa 0.0 0.0 1Glyptothorax fuscus 0.0 0.0 1Odontamblyopus tenuis 0.0 0.0 1Small shrimps 0.0 0.0 1Rhinogobius albimaculatus 0.0 0.0 1Terapon puta 0.0 0.0 1Carangidae sp1. 0.0 0.0 1Vanmanenia serrilineata 0.0 0.0 1Betta splendens 0.0 0.0 1Hemibarbus labeo 0.0 0.0 1Sinilabeo discognathoides 0.0 0.0 1Monotretus turgidus 0.0 0.0 1Clarias nieuhofii 0.0 0.0 1Tetraodon suvattii 0.0 0.0 1Danio albolineatus 0.0 0.0 1Meretrix lyrata 0.0 0.0 1Synaptura commersonnii 0.0 0.0 1Balantiocheilos ambusticauda 0.0 0.0 0.0 2Apocryptodon madurensis 0.0 0.0 1Eugnathogobius oligactis 0.0 0.0 1Bostrychus sinensis 0.0 0.0 0.0 2

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Paraplagusia bilineata 0.0 0.0 1Mystus sp. Red spots Viet Nam 0.0 0.0 1Selaroides leptolepis 0.0 0.0 0.0 2Rhizoprionodon acutus 0.0 0.0 1Taenioides gracilis 0.0 0.0 1Arius microcephalus 0.0 0.0 1Clupeidae sp1. 0.0 0.0 1Tetraodon biocellatus 0.0 0.0 1Poropuntius speleops 0.0 0.0 1Pangio filinaris 0.0 0.0 1Dermogenys siamensis 0.0 0.0 1Stolephorus indicus 0.0 0.0 1Ceratoglanis pachynema 0.0 0.0 1Stolephorus dubiosus 0.0 0.0 1

Note: * p < 0.05; ** p < 0.01


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VILLAGE NAME 2003 2004 2005 2007 2008 2009 2010

Site AMCF FEVM Country Province District AMCF FEVM River Name Habitat Type Order 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 21 1 Lao PDR Bokeo Houixay Ban Done Mekong River Mainstream 1 2 89 686 631 572 775 1913 2374 2887 1150 990 2023 1653 1544 123 114 339 1582 1 Lao PDR Luangprabang Ban Hat Ya Ban Hat Gna Ou River Tributary 2 80 82 68 1154 67 164 129 151 183 206 173 109 226 256 3573 1 1 Lao PDR Luangprabang Luangprabang Ban Pha O Ban Pha O Mekong River Mainstream 3 40 84 78 95 120 82 58 67 92 182 44 45 65 10 20 74 64 69 42 49 64 120 105 119 101 93 119 158 115 664 1 Lao PDR Borikhamxay Paksan Ban Nam Ngieb Ngieb River Tributary 4 82 100 46 33 34 51 55 102 105 74 72 70 89 62 14 9 6 5 25 15 12 325 1 1 Lao PDR Borikhamxay Paksan Ban Xinh Xay Ban Sinhxay Mekong River Mainstream 5 43 157 199 216 206 305 374 267 215 235 232 182 148 201 99 188 96 157 304 267 160 100 207 177 196 298 242 183 124 119 150 112 338 131 174 237 2186 1 Thailand Nongkhai Sri Chiangmai Pa-sak Mekong River Mainstream 6 21 32 82 164 99 35 13 50 177 1 Thailand Nongkhai Sri Chiangmai Huasai Mekong River Mainstream 7 59 68 84 62 19 31 154 97 51 9 13 36 248 1 Thailand Loei Chiangkhan Chiangkhan Chiangkhan Mekong River Mainstream 8 74 9 40 195 201 31 75 120 11 102 26 42 15 319 25 47 21 11 39 675 18 55 86 469 1 Thailand Loei Chiangkhan Noy Noy Mekong River Mainstream 9 89 91 15 31 10 21 39 14 121 495 79 150 38 27 12 20 35 110 125 1151 186 14010 1 1 Lao PDR Vientiane Hatxayfong Ban Thamuang Ban Thamuang Mekong River Mainstream 10 6 26 53 29 61 79 82 65 44 81 45 41 50 27 111 440 426 223 152 218 90 82 144 112 119 110 167 98 34611 1 Thailand Nongkhai Tha Bo Donmee Donmee Huai Mong River Tributary 11 0 19 15 73 74 20 585 57 100 179 48 71 3267 2513 177 64 29 49 89 122 57 75 1812 1 Thailand Nongkhai Tha Bo Thadang Thadang Huai Mong River Tributary 12 34 56 99 82 69 5 65 95 90 119 109 67 132 151 227 179 135 125 220 233 150 212 7013 1 Thailand Nakornpanom Sri Songkhram Tha Bo Tha Bo Songkhram River Floodplain 13 168 85 825 9198 275 1 15 327 240 334 309 491 2292 768 284 198 174 584 468 211 17314 1 Thailand Nakornpanom Tha Utain Chaiyaburi Chaiyaburi Mekong River Mainstream 14 48 123 204 71 34 9 9 74 109 68 74 46 19 30 70 86 78 98 97 66 82 62 1915 1 Lao PDR Khammouane Thakek Ban Mouang Sum Mekong River Mainstream 15 104 120 223 213 196 392 350 482 358 332 326 271 219 247 15216 1 Lao PDR Kham Mouan Tha Ngam Tha Ngam Mekong River Floodplain 1617 1 Thailand Sakolnakorn Phon Nakeaw Phaphang Mekong River Floodplain 17 34 25 75 42 25 39 29 2918 1 Thailand Sakolnakorn Wang Yam Nongbeung Mekong River Floodplain 18 5 7 22 24 26 48 115 2819 1 Thailand Nakornphanom Na Keah Pi man thay Mekong River Floodplain 19 15 46 40 33 28 4 54 49 720 1 Thailand Nakornphanom Tad Phanom Ban Nam Kum Mekong River Mainstream 20 107 36 12 15 8 6 42 272 350 38 33 106 19321 1 Thailand Mukdaharn Wan Yai Song-khon Mekong River Mainstream 21 31 22 496 97 67 44 159 28 27 45 35 70 2822 1 Thailand Mukdaharn Muang Nalair Mekong River Mainstream 22 72 38 36 69 15 30 91 109 5523 1 Thailand Ubon Ratchathani Khemarat Ladcharoen Ladcharoen Mekong River Mainstream 23 191 99 78 174 95 214 252 115 47 202 328 258 97 56 55 100 80 86 53 935 189 112 182 285 7924 1 1 Cambodia Stung Treng Siem Pang Pres Bang Pres Bang Sekong River Tributary 24 94 69 28 83 83 71 130 41 49 66 86 94 53 130 86 100 83 63 38 30 56 166 41 95 185 173 219 244 86 167 124 158 54 84 113 94 87 76 203 100 105 68 68 78 65 97 75 58 37 43 50 51 74 57 53 53 41 84 104 111 92 93 106 8025 1 1 Cambodia Ratanakiri Veounsai Banfang Fang Sesan River Tributary 25 93 168 76 38 72 105 146 90 99 82 90 87 84 186 132 41 147 167 52 27 43 36 39 29 28 51 39 103 33 44 97 43 5 73 54 74 90 47 87 68 78 77 113 71 107 75 52 108 104 155 83 84 110 110 118 100 119 84 96 125 138 131 119 13926 1 1 Cambodia Stung Treng Talarborivat Ou Run Ou Run Mekong River Mainstream 26 304 611 235 228 298 154 141 197 310 165 107 145 520 574 297 224 224 104 92 62 202 13 85 149 180 305 213 153 119 96 59 80 33 334 202 194 62 135 268 194 94 180 446 383 323 265 247 190 218 169 170 406 230 374 491 724 823 1207 352 282 272 237 286 26827 1 Cambodia Stung Treng Stung Treng Kang Memai Mekong River Mainstream 27 76 341 53 11 72 95 134 172 248 124 144 150 288 411 125 54 74 42 12 10 20 50 56 50 47 273 62 30 20 22 16 8 128 1 1 Cambodia Ratanakiri Lum Phat Day Lo Day Lo Srepork River Tributary 28 72 28 31 37 63 153 275 353 436 408 333 411 186 440 579 268 129 172 111 333 438 374 161 197 136 95 75 225 90 185 219 191 32 253 293 89 235 753 706 507 170 440 443 172 305 302 444 393 632 738 554 465 401 664 448 196 372 457 303 263 189 618 720 58529 1 Cambodia Stung Treng Sesan Sre Sronok Srepork River Tributary 29 98 68 25 26 85 183 367 214 403 198 184 178 143 177 149 120 188 12230 1 1 Cambodia Kra Tie Sambo Koh Khne Koh khne Mekong River Mainstream 30 110 311 499 156 211 415 528 341 264 274 171 337 199 290 201 244 265 179 81 83 102 273 202 148 222 123 287 65 151 100 135 61 22 194 183 281 163 156 164 170 291 127 150 87 121 205 155 226 220 198 236 176 162 183 251 213 251 208 265 213 258 463 257 30531 1 Cambodia Kra Tie Sambo Sandan Mekong River Mainstream 31 251 329 343 615 89 143 104 190 273 276 667 756 496 837 741 322 101 55 66 166 283 218 253 367 287 130 377 339 78 91 58 57 4232 1 Cambodia Kampong Cham Kroch Chmar Pram Mekong River Mainstream 32 147 382 252 193 1247 596 321 247 248 158 249 336 540 821 290 272 205 586 805 672 1153 1121 638 581 541 752 702 1173 471 562 827 572 26233 1 Cambodia Kandal Ponhea Leu Peamchumnik Tonle Sap Floodplain 33 227 178 100 74 1568 92 432 46 53 50 42 41 61 2934 1 1 Cambodia Kandal Ponhea Leu Sang Var Sang Var Tonle Sap Tributary 34 169 142 160 90 75 35 61 49 53 43 45 26 25 29 56 17 18 47 23 56 52 64 86 52 28 21 82 80 14 29 38 18 1 70 147 161 99 74 74 60 475 447 311 132 115 157 144 71 123 66 77 117 1162 937 231 64 100 159 134 128 72 186 114 1715 1835 1 Cambodia Kandal Sa Ang Baren Tonle Sap Floodplain 35 269 290 170 93 62 203 216 510 200 130 257 412 582 499 273 55 118 253 301 469 464 288 241 322 293 330 232 25 71 144 358 449 5036 1 Cambodia Kandal Leuk Dek Kbal Chroy Mekong River Floodplain 36 119 653 614 333 370 510 444 399 244 204 256 239 321 392 213 196 162 151 172 242 248 216 214 378 311 331 212 130 170 150 228 200 4437 1 Viet Nam An Giang An Phu Phuoc Hung Bassac River Mainstream 37 3 244 214 258 435 599 224 210 181 131 127 204 145 190 131 424 536 391 727 225 273 208 229 65 290 487 571 30138 1 Viet Nam An Giang An Phu Ap 2 Ap 2 Bassac River Mainstream 38 28 51 231 547 609 384 726 285 409 268 147 391 226 194 395 862 540 516 469 356 531 307 170 260 377 365 544 397 488 541 245 548 2339 1 Viet Nam Dong Thap Hong Ngu An Binh A Mekong River Mainstream 39 122 270 337 862 1274 780 1378 464 447 320 205 238 836 1048 1503 902 1817 153 734 781 629 344 430 577 1822 1444 1424 51040 1 Viet Nam Dong Thap Tam Nong Phu Duc Mekong River Floodplain 40 66 859 1287 46 1043 11772 7440 3263 1700 871 433 170 1189 1632 1538 2370 2737 4866 5261 1084 514 520 708 724 1599 2806 3013 5468 7467 766641 1 Viet Nam An Giang Cho Moi My Thuan My Thuan Bassac River Mainstream 41 81 66 41 326 2028 2391 2629 581 515 466 630 632 511 477 423 478 374 1375 1338 755 467 1942 1 Viet Nam An Giang Phu Tan Vam Nao Vam Nao Vam Nao canal Tributary 42 12 26 473 1654 1926 1517 453 345 371 518 263 187 50 112 284 544 287 188 502 326 463 410 508 665 2139 2595 2397 1166 630 3543 1 Viet Nam Dong Thap An Phu Thap Muoi Mekong River Floodplain 43 670 1192 1101 949 1163 1592 1388 872 694 620 601 605 58644 1 Viet Nam An Giang Tri Ton An Tuc Mekong River Floodplain 44 3 75 95 147 147 244 126 116 58 73 69 46 14 32 231 266 207 565 1609 587 317 333 379 82 310 607 1180 114145 1 Viet Nam Tien Giang Chau Thanh Kim Son Mekong River Mainstream 45 393 62 30 54 37 10 53 183 147 8 193 17 1746 1 Viet Nam Tien Giang Go Cong Tay Phu Thanh Mekong River Mainstream 46 14 298 285 73 16 26 29 38 33 27 19 31 45 39 29 24 30 40 40 40 36 24 20 15 29 14 33 34 36 37 2847 1 Viet Nam Vinh Long TX Vinh Long 39/9A Tran Phu Mekong River Mainstream 47 12 224 432 225 252 189 286 336 392 524 603 34548 1 1 Viet Nam An Giang Thoai Son Tay Son Tay Son Bassac River Floodplain 48 8 115 107 219 245 104 79 30 77 55 64 45 52 73 85 331 573 928 814 467 426 288 229 246 251 283 240 38 626 705 598 507 333 213 217 217 182 174 132 316 813 889 685 509 346 263 2249 1 Viet Nam Vinh Long Vung Liem Thanh Binh Mekong River Mainstream 49 10 313 283 127 113 107 246 272 293 155 271 254 274 349 200 250 280 251 183 157 76 211 186 274 288 193 203 162 169 146 2050 1 Viet Nam Vinh Long Vung Liem Lang Lang Mekong River Mainstream 50 61 76 90 103 129 136 260 367 274 461 432 489 279 183 190 161 170 180 311 330 224 255 378 269 186 169 202 186 298 258 195 151 1 Viet Nam Vinh Long Tra On Khu 9 Bassac River Mainstream 51 9 304 203 176 146 105 280 249 237 209 235 248 483 230 9052 1 Viet Nam Tra Vinh Chau Thanh Dai Thon Mekong River Mainstream 52 47 47 44 83 74 127 77 90 115 120 6653 1 Viet Nam Tra Vinh Tieu Can Khom Dinh Bassac River Mainstream 53 26 371 267 239 222 121 299 196 139 62 265 174 44 98 31 90 234 270 214 288 368 165 185 479 60 90 141 71 12154 1 Viet Nam Tra Vinh Tieu Can Khom 3 Khom 3 Bassac River Estuary 54 170 746 719 668 740 732 930 780 782 540 1505 654 765 601 790 801 1380 694 917 797 744 843 1250 994 633 1056 1227 1294 1382 1206 1638 1281 9

Table 21 Monthlyestimatesofcatchweight(kg)atthefishercatchmonitoringsites(2003–2010)

VILLAGE NAME 2003 2004 2005 2007 2008 2009 2010

Site AMCF FEVM Country Province District AMCF FEVM River Name Habitat Type Order 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 21 1 Lao PDR Bokeo Houixay Ban Done Mekong River Mainstream 1 4 1974 39158 27815 36420 27928 82293 46277 75539 47795 45021 310466 258556 191743 12862 15192 38280 389282 1 Lao PDR Luangprabang Ban Hat Ya Ban Hat Gna Ou River Tributary 2 534 466 299 130 136 108 107 146 314 721 579 588 815 424 1463 1 1 Lao PDR Luangprabang Luangprabang Ban Pha O Ban Pha O Mekong River Mainstream 3 1359 566 552 956 1983 1495 646 756 662 617 692 958 1777 172 175 137 75 49 50 53 254 336 163 282 620 886 270 355 207 3424 1 Lao PDR Borikhamxay Paksan Ban Nam Ngieb Ngieb River Tributary 4 1239 1463 704 595 412 413 397 1227 6311 644 825 1703 1876 686 215 91 84 71 87 78 78 615 1 1 Lao PDR Borikhamxay Paksan Ban Xinh Xay Ban Sinhxay Mekong River Mainstream 5 194 731 534 618 648 1129 941 472 473 487 392 385 366 588 223 413 252 616 1116 621 875 371 358 315 270 465 469 515 312 355 542 492 1489 418 422 382 2716 1 Thailand Nongkhai Sri Chiangmai Pa-sak Mekong River Mainstream 6 25 14 182 1942 1905 12 4 11 47 1 Thailand Nongkhai Sri Chiangmai Huasai Mekong River Mainstream 7 274 178 69 643 45 777 2019 1114 74 8 31 21 508 1 Thailand Loei Chiangkhan Chiangkhan Chiangkhan Mekong River Mainstream 8 258 42 169 978 1441 158 603 115 20 41 7 11 14 129 75 27 14 4 88 95 33 27 17 119 1 Thailand Loei Chiangkhan Noy Noy Mekong River Mainstream 9 69 211 45 55 81 313 867 468 2223 11529 133 312 15 153 255 311 599 1468 4471 6417 220 86610 1 1 Lao PDR Vientiane Hatxayfong Ban Thamuang Ban Thamuang Mekong River Mainstream 10 50 597 1053 1242 2353 2419 1744 585 357 544 705 518 369 488 150 116 111 72 46 93 91 99 1922 2189 1563 102 51 30 10011 1 Thailand Nongkhai Tha Bo Donmee Donmee Huai Mong River Tributary 11 7 322 720 7952 10813 3638 65083 1730 3792 16170 1730 2348 109261 143418 22947 3778 2943 7423 11109 10356 4370 6589 226012 1 Thailand Nongkhai Tha Bo Thadang Thadang Huai Mong River Tributary 12 623 4236 3481 37526 7657 429 1086 1329 2651 4178 1422 958 1976 2398 7221 2223 2142 3510 8757 2942 1146 1209 94913 1 Thailand Nakornpanom Sri Songkhram Tha Bo Tha Bo Songkhram River Floodplain 13 802 1717 48449 236983 4464 1 4 2751 7030 6998 5351 9408 207494 71316 11558 7239 6798 7057 6393 1857 981014 1 Thailand Nakornpanom Tha Utain Chaiyaburi Chaiyaburi Mekong River Mainstream 14 301 201 73 80 21 137 23 44 1006 2692 983 79 6 19 116 773 315 61 189 1846 957 27 815 1 Lao PDR Khammouane Thakek Ban Mouang Sum Mekong River Mainstream 15 921 2255 944 891 673 3700 931 871 2559 280 313 881 577 511 20416 1 Lao PDR Kham Mouan Tha Ngam Tha Ngam Mekong River Floodplain 1617 1 Thailand Sakolnakorn Phon Nakeaw Phaphang Mekong River Floodplain 17 829 610 2348 897 540 670 587 59218 1 Thailand Sakolnakorn Wang Yam Nongbeung Mekong River Floodplain 18 161 216 358 499 959 1263 12048 85519 1 Thailand Nakornphanom Na Keah Pi man thay Mekong River Floodplain 19 72 738 565 428 636 73 1136 1318 17720 1 Thailand Nakornphanom Tad Phanom Ban Nam Kum Mekong River Mainstream 20 2658 839 344 187 188 270 1549 9523 9135 1902 1437 4705 674621 1 Thailand Mukdaharn Wan Yai Song-khon Mekong River Mainstream 21 193 41 29355 4943 42 68 2435 653 14 56 80 217 2322 1 Thailand Mukdaharn Muang Nalair Mekong River Mainstream 22 21 49 25 28 7 11 46 36 1623 1 Thailand Ubon Ratchathani Khemarat Ladcharoen Ladcharoen Mekong River Mainstream 23 101 117 118 99 50 642 146 1415 36 92 107 78 77 47 53 38 33 48 30 4812 275 93 49 51 2524 1 1 Cambodia Stung Treng Siem Pang Pres Bang Pres Bang Sekong River Tributary 24 113 155 460 261 869 3293 1826 2318 1782 1940 2673 2113 2185 3289 2524 4749 3794 3103 1373 1032 356 647 182 3123 892 1970 1643 1255 763 1249 775 915 119 818 954 1104 1739 1757 680 393 504 834 427 725 488 327 431 823 422 236 248 579 233 572 626 1025 592 1341 1071 1521 1538 1786 1322 130925 1 1 Cambodia Ratanakiri Veounsai Banfang Fang Sesan River Tributary 25 239 570 341 269 669 1228 1520 866 1531 1278 1222 1389 1140 3514 1767 614 607 4037 971 344 490 546 1766 719 536 962 679 417 289 380 1846 345 89 2827 872 1503 1949 884 1075 2031 2752 2369 2336 2023 3415 1378 765 1585 5513 2704 2745 1532 2005 3864 4388 2952 2285 1566 1880 4237 4604 2942 6359 362626 1 1 Cambodia Stung Treng Talarborivat Ou Run Ou Run Mekong River Mainstream 26 194 323 101 169 377 392 554 588 689 453 1800 2396 1506 1140 3215 1259 456 350 76 58 156 22 166 267 171 257 192 145 267 89 65 76 36 11035 1556 1381 555 817 749 403 1921 3029 7781 8761 4260 974 490 1045 1029 1390 383 518 602 10699 13737 34884 28072 27803 3222 2091 2669 1050 753 62127 1 Cambodia Stung Treng Stung Treng Kang Memai Mekong River Mainstream 27 1250 2639 1323 533 846 764 1807 677 739 513 5197 7405 11055 7071 1345 776 936 695 533 127 305 2500 3032 3778 3460 8205 1026 360 478 742 485 121 328 1 1 Cambodia Ratanakiri Lum Phat Day Lo Day Lo Srepork River Tributary 28 290 142 109 151 545 1109 1233 705 493 1057 1884 1523 1595 2035 1625 720 703 609 233 677 1322 1188 174 113 243 700 319 423 279 528 588 707 94 1004 634 1098 713 2815 1426 2139 445 1299 1443 819 1502 868 666 1111 1239 1519 1056 1238 1038 1767 1911 1341 1444 1860 1776 1073 1805 2867 1672 132229 1 Cambodia Stung Treng Sesan Sre Sronok Srepork River Tributary 29 524 369 244 279 828 1781 3220 1363 1078 1143 1479 1641 1593 2125 2353 1535 1499 134130 1 1 Cambodia Kra Tie Sambo Koh Khne Koh khne Mekong River Mainstream 30 1506 1520 191 229 1361 1168 2411 1627 1251 1260 818 1841 1534 2365 1867 1517 903 681 784 279 154 873 469 466 13562 3134 7812 734 260 271 548 598 314 9768 439 578 339 1055 1345 1064 1125 550 713 1920 2101 1217 430 636 713 575 1070 1060 999 1180 1460 3694 4749 439 428 550 726 1115 607 75831 1 Cambodia Kra Tie Sambo Sandan Mekong River Mainstream 31 8 45 454 201 781 2122 2970 1668 2219 1724 4555 9357 12400 8788 17786 7426 3023 1613 1442 679 2316 1763 9631 5756 9855 3171 8308 13974 2327 1571 584 553 5232 1 Cambodia Kampong Cham Kroch Chmar Pram Mekong River Mainstream 32 194 189 36 33 755 5720 9641 6164 6833 3897 8041 12492 21469 12788 3151 4683 4253 29190 22231 20230 40290 37805 15424 34089 23549 21737 15535 35550 29767 20371 17944 14746 802333 1 Cambodia Kandal Ponhea Leu Peamchumnik Tonle Sap Floodplain 33 463 1814 4729 3321 2293 2748 1241 2285 2821 2500 1524 2448 4018 193034 1 1 Cambodia Kandal Ponhea Leu Sang Var Sang Var Tonle Sap Tributary 34 292 189 42 206 465 317 1285 1897 2006 1611 1756 1108 762 611 650 466 515 996 793 817 1005 2547 1140 1404 1201 1187 1798 883 649 3004 2589 363 11 1546 3091 3504 4853 1290 1364 1857 34054 42683 8795 3492 2184 5530 4966 1844 2904 1035 1052 2603 161810 86645 4923 1102 1736 3367 2800 3792 2133 22388 1579 226214 277035 1 Cambodia Kandal Sa Ang Baren Tonle Sap Floodplain 35 80 137 131 125 164 1155 1156 347 357 3646 7818 16328 32754 24660 10598 2351 8769 20834 11513 12135 14506 8359 7919 13594 14434 15060 9108 915 4658 6708 7931 14851 129936 1 Cambodia Kandal Leuk Dek Kbal Chroy Mekong River Floodplain 36 274 484 333 248 984 1007 930 1787 1264 627 356 2183 3315 4834 2227 1003 594 831 1223 1503 1424 981 1042 11590 6884 7690 3614 727 587 610 855 1398 25137 1 Viet Nam An Giang An Phu Phuoc Hung Bassac River Mainstream 37 220 11060 9891 29394 40994 21555 10913 10682 9489 8204 7324 5912 6007 29482 17393 26551 23378 7813 19662 6880 6919 5675 5907 1383 21461 17399 14800 698738 1 Viet Nam An Giang An Phu Ap 2 Ap 2 Bassac River Mainstream 38 121 487 9638 47647 27591 17452 37504 5865 5208 1512 834 1913 1318 6123 26108 44707 29782 26877 17884 2145 3033 1817 940 1406 4719 8265 33090 32574 23771 19869 1629 2493 11139 1 Viet Nam Dong Thap Hong Ngu An Binh A Mekong River Mainstream 39 9996 32701 26670 83923 87274 74652 180458 39244 28161 19485 12943 34727 90450 87445 78944 55784 204923 9212 64678 93154 105786 28600 38808 68577 179497 101819 94798 2548940 1 Viet Nam Dong Thap Tam Nong Phu Duc Mekong River Floodplain 40 698 3346 5362 173 45097 536114 338733 150521 74300 29504 11792 4119 20677 10057 11266 63091 111657 95367 54827 12641 7218 6728 9846 10550 14069 17269 19777 90399 59607 6105841 1 Viet Nam An Giang Cho Moi My Thuan My Thuan Bassac River Mainstream 41 931 819 518 38003 216853 230134 306540 14070 13195 10363 12391 13111 12252 11684 10246 10985 20533 114176 107208 26222 14959 45242 1 Viet Nam An Giang Phu Tan Vam Nao Vam Nao Vam Nao canal Tributary 42 200 1850 33209 132597 129720 91030 9046 1322 114 138 4171 10059 2238 7430 19279 20848 1556 1134 3309 5718 13813 12437 13131 19096 126795 157614 152790 40683 18329 67143 1 Viet Nam Dong Thap An Phu Thap Muoi Mekong River Floodplain 43 28052 37332 56447 59833 61504 88599 69482 42150 29059 28731 26992 27977 2349944 1 Viet Nam An Giang Tri Ton An Tuc Mekong River Floodplain 44 1212 2515 3871 60554 49539 110849 60305 59240 31932 38047 34929 19507 5317 8086 11310 20421 24708 72392 241124 74698 45331 47645 57828 12860 36212 56167 81029 6641745 1 Viet Nam Tien Giang Chau Thanh Kim Son Mekong River Mainstream 45 6841 1613 21318 30849 29160 9331 67159 256966 155988 3181 161607 9351 193946 1 Viet Nam Tien Giang Go Cong Tay Phu Thanh Mekong River Mainstream 46 1263 13053 19472 6868 3743 6162 6960 7175 6093 4261 2682 4253 6936 6866 4982 4533 5111 6495 5308 5040 4556 4325 2306 1636 2733 1272 4072 6874 5867 5598 339647 1 Viet Nam Vinh Long TX Vinh Long 39/9A Tran Phu Mekong River Mainstream 47 153 3201 6085 5727 6051 4889 5167 3485 11384 18377 26470 1590148 1 1 Viet Nam An Giang Thoai Son Tay Son Tay Son Bassac River Floodplain 48 138 1973 1071 7283 9622 4021 1078 823 4737 4317 5442 3451 3739 3739 2999 18558 25794 47849 40262 14763 16464 11425 11474 17076 17013 13471 7406 489 31275 31422 25574 15398 15803 9357 8600 13051 13054 10485 6096 14171 37166 41011 33427 17316 10044 12147 105049 1 Viet Nam Vinh Long Vung Liem Thanh Binh Mekong River Mainstream 49 530 6912 4207 7692 8787 8231 17346 20661 18342 18228 33348 39453 47049 56986 39191 49353 49101 37547 36785 34360 15602 44421 36315 58026 59287 42336 36715 31357 34749 27964 538750 1 Viet Nam Vinh Long Vung Liem Lang Lang Mekong River Mainstream 50 2732 4162 6413 5598 5093 5919 9728 10809 6545 9473 12271 12359 11625 8614 9259 7615 7465 7438 11961 6809 4601 5594 15769 14139 11060 11581 10827 9144 4585 10772 10414 6321 2951 1 Viet Nam Vinh Long Tra On Khu 9 Bassac River Mainstream 51 125 4218 2958 10591 18631 12730 68098 40326 31135 114136 56185 64764 50127 23859 764652 1 Viet Nam Tra Vinh Chau Thanh Dai Thon Mekong River Mainstream 52 1523 2042 10722 26288 16994 20518 14457 15064 19909 27683 1892153 1 Viet Nam Tra Vinh Tieu Can Khom Dinh Bassac River Mainstream 53 511 7865 6011 34971 37888 33484 47455 28774 19781 9403 49771 34232 8882 21343 7072 28864 55952 51260 47168 50745 14867 33608 40682 111736 12768 22395 30206 18813 3414854 1 Viet Nam Tra Vinh Tieu Can Khom 3 Khom 3 Bassac River Estuary 54 4802 31515 18880 10563 11800 14601 13303 14120 24121 18672 35419 17922 19752 16670 22350 22918 30661 16828 21117 18365 18639 20511 23205 20597 15626 21710 29922 32214 49793 31451 44843 33828 446

Table 22 Monthlyestimatesofthenumberoffishcaughtatthefishercatchmonitoringsites(2003–2010)

VILLAGE NAME 2003 2004 2005 2007 2008 2009 2010

Site AMCF FEVM Country Province District AMCF FEVM River Name Habitat Type Order 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 21 1 Lao PDR Bokeo Houixay Ban Done Mekong River Mainstream 1 0.438 0.045 0.018 0.023 0.016 0.028 0.023 0.051 0.038 0.024 0.022 0.007 0.006 0.008 0.010 0.007 0.009 0.0042 1 Lao PDR Luangprabang Ban Hat Ya Ban Hat Gna Ou River Tributary 2 0.150 0.176 0.227 8.875 0.494 1.520 1.208 1.034 0.582 0.285 0.299 0.185 0.278 0.604 2.4453 1 1 Lao PDR Luangprabang Luangprabang Ban Pha O Ban Pha O Mekong River Mainstream 3 0.030 0.148 0.141 0.099 0.060 0.055 0.090 0.089 0.138 0.294 0.064 0.047 0.037 0.061 0.112 0.540 0.854 1.408 0.831 0.922 0.250 0.356 0.646 0.422 0.163 0.105 0.442 0.446 0.555 0.1934 1 Lao PDR Borikhamxay Paksan Ban Nam Ngieb Ngieb River Tributary 4 0.066 0.068 0.065 0.056 0.084 0.123 0.139 0.084 0.017 0.115 0.087 0.041 0.048 0.090 0.065 0.098 0.073 0.068 0.286 0.197 0.149 0.5175 1 1 Lao PDR Borikhamxay Paksan Ban Xinh Xay Ban Sinhxay Mekong River Mainstream 5 0.222 0.215 0.373 0.350 0.318 0.270 0.397 0.566 0.454 0.482 0.593 0.474 0.405 0.341 0.443 0.456 0.382 0.255 0.273 0.430 0.183 0.271 0.577 0.563 0.727 0.641 0.517 0.356 0.397 0.336 0.276 0.227 0.227 0.314 0.412 0.621 0.8036 1 Thailand Nongkhai Sri Chiangmai Pa-sak Mekong River Mainstream 6 0.832 2.286 0.448 0.084 0.052 2.942 3.250 4.536 4.3257 1 Thailand Nongkhai Sri Chiangmai Huasai Mekong River Mainstream 7 0.214 0.380 1.217 0.096 0.412 0.040 0.077 0.087 0.683 1.063 0.408 1.738 0.4868 1 Thailand Loei Chiangkhan Chiangkhan Chiangkhan Mekong River Mainstream 8 0.287 0.210 0.239 0.200 0.140 0.196 0.125 1.045 0.568 2.480 3.771 3.836 1.050 2.471 0.336 1.752 1.507 2.625 0.439 7.109 0.556 2.055 5.059 4.2009 1 Thailand Loei Chiangkhan Noy Noy Mekong River Mainstream 9 1.290 0.429 0.332 0.571 0.125 0.066 0.045 0.030 0.054 0.043 0.597 0.482 2.553 0.177 0.047 0.063 0.058 0.075 0.028 0.179 0.845 0.16110 1 1 Lao PDR Vientiane Hatxayfong Ban Thamuang Ban Thamuang Mekong River Mainstream 10 0.130 0.043 0.050 0.024 0.026 0.033 0.047 0.112 0.124 0.149 0.064 0.079 0.135 0.056 0.740 3.797 3.837 3.090 3.315 2.347 0.984 0.823 0.075 0.051 0.076 1.080 3.276 3.267 3.45811 1 Thailand Nongkhai Tha Bo Donmee Donmee Huai Mong River Tributary 11 0.057 0.058 0.020 0.009 0.007 0.005 0.009 0.033 0.026 0.011 0.028 0.030 0.030 0.018 0.008 0.017 0.010 0.007 0.008 0.012 0.013 0.011 0.00812 1 Thailand Nongkhai Tha Bo Thadang Thadang Huai Mong River Tributary 12 0.054 0.013 0.028 0.002 0.009 0.012 0.060 0.071 0.034 0.029 0.077 0.070 0.067 0.063 0.031 0.080 0.063 0.036 0.025 0.079 0.131 0.175 0.07413 1 Thailand Nakornpanom Sri Songkhram Tha Bo Tha Bo Songkhram River Floodplain 13 0.210 0.049 0.017 0.039 0.062 0.950 3.650 0.119 0.034 0.048 0.058 0.052 0.011 0.011 0.025 0.027 0.026 0.083 0.073 0.114 0.01814 1 Thailand Nakornpanom Tha Utain Chaiyaburi Chaiyaburi Mekong River Mainstream 14 0.160 0.612 2.799 0.884 1.605 0.067 0.400 1.682 0.108 0.025 0.075 0.581 3.183 1.600 0.601 0.111 0.248 1.613 0.512 0.036 0.086 2.285 2.31315 1 Lao PDR Khammouane Thakek Ban Mouang Sum Mekong River Mainstream 15 0.113 0.053 0.236 0.239 0.292 0.106 0.376 0.554 0.140 1.185 1.042 0.307 0.380 0.483 0.74716 1 Lao PDR Kham Mouan Tha Ngam Tha Ngam Mekong River Floodplain 1617 1 Thailand Sakolnakorn Phon Nakeaw Phaphang Mekong River Floodplain 17 0.041 0.041 0.032 0.046 0.046 0.058 0.050 0.04918 1 Thailand Sakolnakorn Wang Yam Nongbeung Mekong River Floodplain 18 0.033 0.032 0.061 0.048 0.027 0.038 0.010 0.03319 1 Thailand Nakornphanom Na Keah Pi man thay Mekong River Floodplain 19 0.205 0.063 0.070 0.076 0.044 0.051 0.048 0.037 0.03820 1 Thailand Nakornphanom Tad Phanom Ban Nam Kum Mekong River Mainstream 20 0.040 0.042 0.035 0.080 0.042 0.024 0.027 0.029 0.038 0.020 0.023 0.022 0.02921 1 Thailand Mukdaharn Wan Yai Song-khon Mekong River Mainstream 21 0.162 0.534 0.017 0.020 1.602 0.647 0.065 0.043 1.936 0.800 0.431 0.323 1.22222 1 Thailand Mukdaharn Muang Nalair Mekong River Mainstream 22 3.405 0.780 1.428 2.468 2.157 2.691 1.972 3.019 3.41323 1 Thailand Ubon Ratchathani Khemarat Ladcharoen Ladcharoen Mekong River Mainstream 23 1.888 0.844 0.662 1.760 1.908 0.333 1.728 0.081 1.310 2.193 3.063 3.301 1.257 1.187 1.043 2.621 2.427 1.790 1.777 0.194 0.688 1.203 3.722 5.580 3.14824 1 1 Cambodia Stung Treng Siem Pang Pres Bang Pres Bang Sekong River Tributary 24 0.834 0.447 0.062 0.320 0.096 0.022 0.071 0.018 0.028 0.034 0.032 0.044 0.024 0.039 0.034 0.021 0.022 0.020 0.028 0.029 0.159 0.256 0.223 0.031 0.207 0.088 0.133 0.194 0.113 0.134 0.159 0.173 0.458 0.102 0.118 0.085 0.050 0.043 0.298 0.254 0.208 0.082 0.159 0.107 0.133 0.295 0.174 0.070 0.087 0.181 0.203 0.088 0.318 0.100 0.085 0.051 0.069 0.063 0.098 0.073 0.060 0.052 0.080 0.06125 1 1 Cambodia Ratanakiri Veounsai Banfang Fang Sesan River Tributary 25 0.390 0.295 0.222 0.140 0.108 0.085 0.096 0.104 0.065 0.064 0.073 0.062 0.073 0.053 0.075 0.067 0.241 0.041 0.053 0.079 0.087 0.067 0.022 0.041 0.053 0.053 0.058 0.248 0.116 0.116 0.052 0.125 0.061 0.026 0.062 0.049 0.046 0.053 0.081 0.034 0.028 0.033 0.048 0.035 0.031 0.055 0.068 0.068 0.019 0.057 0.030 0.055 0.055 0.029 0.027 0.034 0.052 0.053 0.051 0.030 0.030 0.044 0.019 0.03826 1 1 Cambodia Stung Treng Talarborivat Ou Run Ou Run Mekong River Mainstream 26 1.569 1.893 2.328 1.348 0.790 0.393 0.254 0.336 0.450 0.365 0.059 0.061 0.345 0.504 0.092 0.178 0.491 0.296 1.206 1.076 1.296 0.600 0.513 0.560 1.054 1.186 1.108 1.058 0.446 1.077 0.912 1.053 0.910 0.030 0.130 0.141 0.112 0.165 0.357 0.482 0.049 0.059 0.057 0.044 0.076 0.272 0.505 0.182 0.212 0.122 0.444 0.784 0.382 0.035 0.036 0.021 0.029 0.043 0.109 0.135 0.102 0.226 0.380 0.43127 1 Cambodia Stung Treng Stung Treng Kang Memai Mekong River Mainstream 27 0.061 0.129 0.040 0.021 0.085 0.124 0.074 0.255 0.335 0.241 0.028 0.020 0.026 0.058 0.093 0.070 0.079 0.060 0.022 0.083 0.066 0.020 0.019 0.013 0.014 0.033 0.060 0.084 0.041 0.029 0.033 0.064 0.27828 1 1 Cambodia Ratanakiri Lum Phat Day Lo Day Lo Srepork River Tributary 28 0.248 0.197 0.287 0.247 0.116 0.138 0.223 0.500 0.884 0.386 0.177 0.270 0.116 0.216 0.356 0.373 0.183 0.283 0.474 0.492 0.332 0.315 0.926 1.742 0.559 0.136 0.234 0.533 0.321 0.351 0.373 0.271 0.339 0.252 0.462 0.081 0.330 0.268 0.495 0.237 0.382 0.338 0.307 0.210 0.203 0.348 0.667 0.354 0.510 0.486 0.524 0.376 0.386 0.376 0.234 0.146 0.258 0.246 0.171 0.245 0.105 0.215 0.431 0.44329 1 Cambodia Stung Treng Sesan Sre Sronok Srepork River Tributary 29 0.188 0.185 0.104 0.094 0.103 0.103 0.114 0.157 0.374 0.173 0.124 0.109 0.090 0.083 0.063 0.078 0.125 0.09130 1 1 Cambodia Kra Tie Sambo Koh Khne Koh khne Mekong River Mainstream 30 0.073 0.205 2.610 0.683 0.155 0.356 0.219 0.210 0.211 0.218 0.209 0.183 0.130 0.123 0.107 0.161 0.294 0.263 0.103 0.298 0.660 0.312 0.432 0.318 0.016 0.039 0.037 0.089 0.582 0.370 0.246 0.103 0.069 0.020 0.418 0.486 0.482 0.148 0.122 0.160 0.259 0.231 0.210 0.045 0.058 0.168 0.360 0.356 0.308 0.345 0.221 0.166 0.162 0.155 0.172 0.058 0.053 0.473 0.620 0.388 0.356 0.415 0.424 0.40331 1 Cambodia Kra Tie Sambo Sandan Mekong River Mainstream 31 31.363 7.307 0.755 3.060 0.113 0.068 0.035 0.114 0.123 0.160 0.146 0.081 0.040 0.095 0.042 0.043 0.033 0.034 0.046 0.244 0.122 0.124 0.026 0.064 0.029 0.041 0.045 0.024 0.034 0.058 0.099 0.103 0.80632 1 Cambodia Kampong Cham Kroch Chmar Pram Mekong River Mainstream 32 0.760 2.023 6.987 5.841 1.652 0.104 0.033 0.040 0.036 0.041 0.031 0.027 0.025 0.064 0.092 0.058 0.048 0.020 0.036 0.033 0.029 0.030 0.041 0.017 0.023 0.035 0.045 0.033 0.016 0.028 0.046 0.039 0.03333 1 Cambodia Kandal Ponhea Leu Peamchumnik Tonle Sap Floodplain 33 0.491 0.098 0.021 0.022 0.684 0.034 0.348 0.020 0.019 0.020 0.027 0.017 0.015 0.01534 1 1 Cambodia Kandal Ponhea Leu Sang Var Sang Var Tonle Sap Tributary 34 0.580 0.749 3.805 0.437 0.161 0.111 0.048 0.026 0.026 0.027 0.026 0.024 0.033 0.048 0.085 0.037 0.034 0.047 0.029 0.069 0.052 0.025 0.076 0.037 0.024 0.018 0.045 0.090 0.022 0.010 0.015 0.051 0.109 0.045 0.047 0.046 0.020 0.058 0.054 0.032 0.014 0.010 0.035 0.038 0.053 0.028 0.029 0.039 0.042 0.063 0.073 0.045 0.007 0.011 0.047 0.058 0.058 0.047 0.048 0.034 0.034 0.008 0.072 0.008 0.00635 1 Cambodia Kandal Sa Ang Baren Tonle Sap Floodplain 35 3.367 2.117 1.301 0.744 0.378 0.176 0.187 1.469 0.560 0.036 0.033 0.025 0.018 0.020 0.026 0.023 0.013 0.012 0.026 0.039 0.032 0.034 0.030 0.024 0.020 0.022 0.025 0.027 0.015 0.021 0.045 0.030 0.03836 1 Cambodia Kandal Leuk Dek Kbal Chroy Mekong River Floodplain 36 0.433 1.349 1.843 1.344 0.376 0.507 0.477 0.224 0.193 0.326 0.720 0.110 0.097 0.081 0.095 0.196 0.272 0.181 0.141 0.161 0.174 0.220 0.206 0.033 0.045 0.043 0.059 0.179 0.289 0.245 0.266 0.143 0.17437 1 Viet Nam An Giang An Phu Phuoc Hung Bassac River Mainstream 37 0.013 0.022 0.022 0.009 0.011 0.028 0.020 0.020 0.019 0.016 0.017 0.035 0.024 0.006 0.008 0.016 0.023 0.050 0.037 0.033 0.040 0.037 0.039 0.047 0.014 0.028 0.039 0.04338 1 Viet Nam An Giang An Phu Ap 2 Ap 2 Bassac River Mainstream 38 0.227 0.105 0.024 0.011 0.022 0.022 0.019 0.049 0.078 0.177 0.176 0.204 0.171 0.032 0.015 0.019 0.018 0.019 0.026 0.166 0.175 0.169 0.181 0.185 0.080 0.044 0.016 0.012 0.021 0.027 0.150 0.220 0.20839 1 Viet Nam Dong Thap Hong Ngu An Binh A Mekong River Mainstream 39 0.012 0.008 0.013 0.010 0.015 0.010 0.008 0.012 0.016 0.016 0.016 0.007 0.009 0.012 0.019 0.016 0.009 0.017 0.011 0.008 0.006 0.012 0.011 0.008 0.010 0.014 0.015 0.02040 1 Viet Nam Dong Thap Tam Nong Phu Duc Mekong River Floodplain 40 0.094 0.257 0.240 0.265 0.023 0.022 0.022 0.022 0.023 0.030 0.037 0.041 0.058 0.162 0.137 0.038 0.025 0.051 0.096 0.086 0.071 0.077 0.072 0.069 0.114 0.162 0.152 0.060 0.125 0.12641 1 Viet Nam An Giang Cho Moi My Thuan My Thuan Bassac River Mainstream 41 0.087 0.080 0.079 0.009 0.009 0.010 0.009 0.041 0.039 0.045 0.051 0.048 0.042 0.041 0.041 0.044 0.018 0.012 0.012 0.029 0.031 0.04242 1 Viet Nam An Giang Phu Tan Vam Nao Vam Nao Vam Nao canal Tributary 42 0.058 0.014 0.014 0.012 0.015 0.017 0.050 0.261 3.255 3.755 0.063 0.019 0.022 0.015 0.015 0.026 0.184 0.166 0.152 0.057 0.034 0.033 0.039 0.035 0.017 0.016 0.016 0.029 0.034 0.05343 1 Viet Nam Dong Thap An Phu Thap Muoi Mekong River Floodplain 43 0.024 0.032 0.020 0.016 0.019 0.018 0.020 0.021 0.024 0.022 0.022 0.022 0.02544 1 Viet Nam An Giang Tri Ton An Tuc Mekong River Floodplain 44 0.002 0.030 0.025 0.002 0.003 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.003 0.004 0.020 0.013 0.008 0.008 0.007 0.008 0.007 0.007 0.007 0.006 0.009 0.011 0.015 0.01745 1 Viet Nam Tien Giang Chau Thanh Kim Son Mekong River Mainstream 45 0.058 0.039 0.001 0.002 0.001 0.001 0.001 0.001 0.001 0.002 0.001 0.002 0.00946 1 Viet Nam Tien Giang Go Cong Tay Phu Thanh Mekong River Mainstream 46 0.011 0.023 0.015 0.011 0.004 0.004 0.004 0.005 0.005 0.006 0.007 0.007 0.006 0.006 0.006 0.005 0.006 0.006 0.008 0.008 0.008 0.006 0.008 0.009 0.011 0.011 0.008 0.005 0.006 0.007 0.00847 1 Viet Nam Vinh Long TX Vinh Long 39/9A Tran Phu Mekong River Mainstream 47 0.079 0.070 0.071 0.039 0.042 0.039 0.055 0.096 0.034 0.028 0.023 0.02248 1 1 Viet Nam An Giang Thoai Son Tay Son Tay Son Bassac River Floodplain 48 0.058 0.058 0.100 0.030 0.025 0.026 0.074 0.037 0.016 0.013 0.012 0.013 0.014 0.019 0.028 0.018 0.022 0.019 0.020 0.032 0.026 0.025 0.020 0.014 0.015 0.021 0.032 0.078 0.020 0.022 0.023 0.033 0.021 0.023 0.025 0.017 0.014 0.017 0.022 0.022 0.022 0.022 0.020 0.029 0.034 0.022 0.02149 1 Viet Nam Vinh Long Vung Liem Thanh Binh Mekong River Mainstream 49 0.018 0.045 0.067 0.016 0.013 0.013 0.014 0.013 0.016 0.008 0.008 0.006 0.006 0.006 0.005 0.005 0.006 0.007 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.006 0.005 0.005 0.005 0.00450 1 Viet Nam Vinh Long Vung Liem Lang Lang Mekong River Mainstream 50 0.022 0.018 0.014 0.018 0.025 0.023 0.027 0.034 0.042 0.049 0.035 0.040 0.024 0.021 0.021 0.021 0.023 0.024 0.026 0.048 0.049 0.046 0.024 0.019 0.017 0.015 0.019 0.019 0.041 0.028 0.025 0.031 0.03651 1 Viet Nam Vinh Long Tra On Khu 9 Bassac River Mainstream 51 0.072 0.072 0.069 0.017 0.008 0.008 0.004 0.006 0.008 0.002 0.004 0.004 0.010 0.010 0.01252 1 Viet Nam Tra Vinh Chau Thanh Dai Thon Mekong River Mainstream 52 0.031 0.023 0.004 0.003 0.004 0.006 0.005 0.006 0.006 0.004 0.00353 1 Viet Nam Tra Vinh Tieu Can Khom Dinh Bassac River Mainstream 53 0.051 0.047 0.044 0.007 0.006 0.004 0.006 0.007 0.007 0.007 0.005 0.005 0.005 0.005 0.004 0.003 0.004 0.005 0.005 0.006 0.025 0.005 0.005 0.004 0.005 0.004 0.005 0.004 0.00454 1 Viet Nam Tra Vinh Tieu Can Khom 3 Khom 3 Bassac River Estuary 54 0.035 0.024 0.038 0.063 0.063 0.050 0.070 0.055 0.032 0.029 0.042 0.037 0.039 0.036 0.035 0.035 0.045 0.041 0.043 0.043 0.040 0.041 0.054 0.048 0.041 0.049 0.041 0.040 0.028 0.038 0.037 0.038 0.019

Table 23 Monthlyestimatesofthemeanweight(kg)offishcaughtatthefishercatchmonitoringsites(2003–2010)


VILLAGE NAME 2003 2004 2005 2007 2008 2009 2010

Site AMCF FEVM Country Province District AMCF FEVM River Name Habitat Type Order 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 21 1 Lao PDR Bokeo Houixay Ban Done Mekong River Mainstream 1 3 52 32 34 32 30 33 31 32 32 31 28 35 31 8 9 9 52 1 Lao PDR Luangprabang Ban Hat Ya Ban Hat Gna Ou River Tributary 2 9 8 19 34 24 18 14 17 30 28 40 33 34 32 333 1 1 Lao PDR Luangprabang Luangprabang Ban Pha O Ban Pha O Mekong River Mainstream 3 25 24 25 24 24 30 20 28 30 23 26 24 30 20 9 17 20 11 16 14 23 24 17 21 26 17 15 18 11 164 1 Lao PDR Borikhamxay Paksan Ban Nam Ngieb Ngieb River Tributary 4 52 47 57 43 41 49 46 56 50 48 58 54 57 60 22 28 24 30 36 28 23 315 1 1 Lao PDR Borikhamxay Paksan Ban Xinh Xay Ban Sinhxay Mekong River Mainstream 5 33 35 47 39 44 45 39 41 42 39 42 51 37 57 25 16 19 17 22 24 7 11 18 29 23 21 29 39 31 28 25 25 25 21 14 18 166 1 Thailand Nongkhai Sri Chiangmai Pa-sak Mekong River Mainstream 6 5 9 19 12 7 8 4 3 37 1 Thailand Nongkhai Sri Chiangmai Huasai Mekong River Mainstream 7 29 27 18 32 12 17 27 27 18 3 5 12 128 1 Thailand Loei Chiangkhan Chiangkhan Chiangkhan Mekong River Mainstream 8 14 8 16 12 11 5 17 13 6 11 1 1 5 8 7 3 3 1 9 10 7 7 2 29 1 Thailand Loei Chiangkhan Noy Noy Mekong River Mainstream 9 8 7 6 3 16 19 19 8 21 24 9 8 6 10 7 9 17 12 10 15 10 1810 1 1 Lao PDR Vientiane Hatxayfong Ban Thamuang Ban Thamuang Mekong River Mainstream 10 7 12 20 18 17 16 18 17 14 20 16 18 17 15 13 14 12 13 14 18 13 7 8 8 7 10 10 9 1211 1 Thailand Nongkhai Tha Bo Donmee Donmee Huai Mong River Tributary 11 1 10 23 31 35 25 27 24 27 29 37 13 42 42 30 23 17 25 19 24 22 22 2312 1 Thailand Nongkhai Tha Bo Thadang Thadang Huai Mong River Tributary 12 9 14 26 21 10 14 14 16 21 12 15 19 39 24 27 25 21 23 23 18 8 5 113 1 Thailand Nakornpanom Sri Songkhram Tha Bo Tha Bo Songkhram River Floodplain 13 44 43 63 38 28 1 1 23 46 35 34 33 39 34 23 26 15 34 31 12 2114 1 Thailand Nakornpanom Tha Utain Chaiyaburi Chaiyaburi Mekong River Mainstream 14 8 25 19 14 6 4 4 3 19 17 14 14 5 11 15 20 14 2 4 13 13 4 315 1 Lao PDR Khammouane Thakek Ban Mouang Sum Mekong River Mainstream 15 24 39 30 34 25 35 33 30 35 26 23 24 31 29 1216 1 Lao PDR Kham Mouan Tha Ngam Tha Ngam Mekong River Floodplain 1617 1 Thailand Sakolnakorn Phon Nakeaw Phaphang Mekong River Floodplain 17 23 17 26 17 21 20 16 1518 1 Thailand Sakolnakorn Wang Yam Nongbeung Mekong River Floodplain 18 10 12 15 16 18 16 15 1519 1 Thailand Nakornphanom Na Keah Pi man thay Mekong River Floodplain 19 8 15 19 30 31 15 34 55 1820 1 Thailand Nakornphanom Tad Phanom Ban Nam Kum Mekong River Mainstream 20 44 27 11 9 17 8 21 29 33 19 27 28 2221 1 Thailand Mukdaharn Wan Yai Song-khon Mekong River Mainstream 21 16 8 15 13 11 10 19 5 4 4 6 14 822 1 Thailand Mukdaharn Muang Nalair Mekong River Mainstream 22 4 5 3 5 4 5 9 5 423 1 Thailand Ubon Ratchathani Khemarat Ladcharoen Ladcharoen Mekong River Mainstream 23 22 19 18 11 17 27 19 16 9 16 14 7 13 10 8 6 8 9 9 14 32 14 10 6 424 1 1 Cambodia Stung Treng Siem Pang Pres Bang Pres Bang Sekong River Tributary 24 9 7 12 27 46 52 60 58 57 56 58 63 62 58 55 47 33 53 34 28 20 22 15 24 23 35 33 27 34 39 39 41 16 74 61 52 61 69 61 43 48 43 31 44 39 36 35 47 38 39 24 50 40 45 54 58 50 52 56 46 43 46 36 3625 1 1 Cambodia Ratanakiri Veounsai Banfang Fang Sesan River Tributary 25 11 16 17 16 48 62 63 62 51 57 51 50 46 87 51 41 55 45 22 22 31 30 25 24 24 34 30 35 32 27 34 27 13 52 46 57 54 37 41 45 53 60 59 60 61 52 49 61 56 53 61 43 54 48 52 64 52 42 45 57 52 41 38 4126 1 1 Cambodia Stung Treng Talarborivat Ou Run Ou Run Mekong River Mainstream 26 25 33 26 47 56 60 63 49 55 34 54 56 63 72 65 64 58 45 32 22 37 8 35 24 31 34 31 38 36 27 31 25 19 85 74 70 52 64 64 46 59 56 76 72 63 76 55 62 67 66 45 44 51 78 81 66 58 78 68 82 76 76 84 4627 1 Cambodia Stung Treng Stung Treng Kang Memai Mekong River Mainstream 27 23 40 39 32 75 79 97 79 55 63 82 77 83 77 64 76 77 70 52 20 35 47 52 45 38 55 42 28 41 30 41 27 328 1 1 Cambodia Ratanakiri Lum Phat Day Lo Day Lo Srepork River Tributary 28 9 10 8 7 63 72 77 54 51 67 82 68 71 74 61 45 53 54 15 32 30 33 21 19 24 32 22 20 24 31 14 20 12 59 66 86 56 70 42 59 49 51 52 58 69 48 38 61 45 58 42 33 34 40 59 52 47 45 68 48 51 51 47 4629 1 Cambodia Stung Treng Sesan Sre Sronok Srepork River Tributary 29 11 11 9 33 69 96 99 95 72 88 77 84 85 92 88 75 73 7530 1 1 Cambodia Kra Tie Sambo Koh Khne Koh khne Mekong River Mainstream 30 41 54 36 42 87 82 86 87 83 80 80 98 102 107 81 89 77 73 38 42 24 55 43 41 49 51 56 48 46 35 38 59 25 80 56 65 61 68 78 65 77 70 81 69 56 62 63 77 61 68 60 84 79 83 95 71 75 58 60 59 67 73 67 6631 1 Cambodia Kra Tie Sambo Sandan Mekong River Mainstream 31 7 9 27 24 71 72 71 63 54 48 55 56 56 60 58 72 74 56 46 50 30 34 42 44 40 41 44 46 51 51 30 31 1532 1 Cambodia Kampong Cham Kroch Chmar Pram Mekong River Mainstream 32 15 17 11 11 78 78 80 69 62 48 58 62 55 58 56 51 66 77 74 50 55 51 37 45 44 44 49 52 55 60 61 45 3733 1 Cambodia Kandal Ponhea Leu Peamchumnik Tonle Sap Floodplain 33 75 71 71 60 60 57 37 35 16 22 24 28 29 3034 1 1 Cambodia Kandal Ponhea Leu Sang Var Sang Var Tonle Sap Tributary 34 36 31 22 28 36 31 37 42 29 35 28 31 25 30 35 36 35 41 36 30 26 36 32 32 24 24 39 19 23 28 26 22 3 62 53 57 64 67 64 52 59 44 56 42 45 37 44 61 71 57 53 61 45 61 51 39 36 40 44 55 57 52 62 57 2635 1 Cambodia Kandal Sa Ang Baren Tonle Sap Floodplain 35 28 30 31 23 49 55 63 58 38 34 34 38 44 40 46 36 42 42 50 42 40 36 32 42 35 38 33 41 45 35 46 40 2236 1 Cambodia Kandal Leuk Dek Kbal Chroy Mekong River Floodplain 36 12 7 8 5 6 6 8 8 8 6 13 12 7 9 27 21 22 10 7 10 5 7 3 4 2 4 14 11 9 8 13 11 937 1 Viet Nam An Giang An Phu Phuoc Hung Bassac River Mainstream 37 14 47 35 26 60 58 55 43 40 46 36 35 31 30 15 19 28 17 28 32 25 28 28 15 13 22 23 2038 1 Viet Nam An Giang An Phu Ap 2 Ap 2 Bassac River Mainstream 38 8 14 33 29 22 18 25 24 15 11 8 14 14 18 13 14 16 17 22 18 19 17 14 13 22 25 21 19 20 19 18 18 639 1 Viet Nam Dong Thap Hong Ngu An Binh A Mekong River Mainstream 39 38 39 41 40 47 44 33 44 41 29 30 36 34 34 41 53 45 22 41 37 41 34 23 37 29 32 24 2440 1 Viet Nam Dong Thap Tam Nong Phu Duc Mekong River Floodplain 40 32 33 27 8 35 34 40 23 19 18 18 17 22 19 22 31 44 51 34 23 24 22 31 24 27 33 41 37 42 3741 1 Viet Nam An Giang Cho Moi My Thuan My Thuan Bassac River Mainstream 41 11 11 12 11 29 30 24 62 71 64 62 60 56 52 49 52 55 21 22 47 35 1742 1 Viet Nam An Giang Phu Tan Vam Nao Vam Nao Vam Nao canal Tributary 42 4 4 20 31 27 28 26 17 10 11 19 15 9 11 29 51 44 27 36 39 40 47 47 37 31 37 37 43 32 843 1 Viet Nam Dong Thap An Phu Thap Muoi Mekong River Floodplain 43 11 32 20 23 33 34 30 19 23 24 23 25 19 2144 1 Viet Nam An Giang Tri Ton An Tuc Mekong River Floodplain 44 6 20 15 27 24 28 23 15 14 14 14 18 17 13 18 25 24 14 19 20 19 16 12 10 28 26 35 2045 1 Viet Nam Tien Giang Chau Thanh Kim Son Mekong River Mainstream 45 45 30 26 27 37 22 30 31 38 12 54 26 2846 1 Viet Nam Tien Giang Go Cong Tay Phu Thanh Mekong River Mainstream 46 15 35 30 57 47 45 44 43 40 36 34 37 42 40 37 34 48 48 44 39 43 28 37 25 31 31 32 34 37 48 3547 1 Viet Nam Vinh Long TX Vinh Long 39/9A Tran Phu Mekong River Mainstream 47 11 21 32 19 15 24 28 18 20 17 22 1648 1 1 Viet Nam An Giang Thoai Son Tay Son Tay Son Bassac River Floodplain 48 3 9 6 9 7 10 14 10 9 12 6 5 9 9 16 23 19 19 22 26 29 25 22 20 19 23 24 8 18 19 18 19 23 22 24 20 20 24 14 20 21 20 21 25 22 20 1149 1 Viet Nam Vinh Long Vung Liem Thanh Binh Mekong River Mainstream 49 2 21 19 24 17 22 34 27 22 21 13 18 16 16 12 14 11 16 18 9 9 9 9 10 11 17 15 13 12 10 850 1 Viet Nam Vinh Long Vung Liem Lang Lang Mekong River Mainstream 50 12 12 10 11 14 14 18 19 17 17 19 18 19 18 23 19 14 18 21 19 21 20 20 18 18 17 16 17 16 17 16 18 751 1 Viet Nam Vinh Long Tra On Khu 9 Bassac River Mainstream 51 6 22 12 19 11 17 18 13 23 18 17 22 22 21 1552 1 Viet Nam Tra Vinh Chau Thanh Dai Thon Mekong River Mainstream 52 17 13 18 14 14 23 26 24 22 24 2153 1 Viet Nam Tra Vinh Tieu Can Khom Dinh Bassac River Mainstream 53 11 51 39 56 40 50 57 55 44 34 50 45 39 43 39 61 78 62 75 65 69 46 43 50 41 48 44 45 5054 1 Viet Nam Tra Vinh Tieu Can Khom 3 Khom 3 Bassac River Estuary 54 18 21 19 15 21 33 21 14 13 15 18 22 23 22 30 31 29 35 27 23 22 33 18 21 17 22 25 26 27 38 29 28 4

Table 24 Monthlyestimatesofthenumberofspeciesreported(S)atthefishercatchmonitoringsites(2003–2010)

VILLAGE NAME 2003 2004 2005 2007 2008 2009 2010

Site AMCF FEVM Country Province District AMCF FEVM River Name Habitat Type Order 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 21 1 Lao PDR Bokeo Houixay Ban Done Mekong River Mainstream 1 1.44 6.72 2.93 3.22 2.95 2.83 2.83 2.79 2.76 2.88 2.80 2.14 2.73 2.47 0.74 0.83 0.76 0.382 1 Lao PDR Luangprabang Ban Hat Ya Ban Hat Gna Ou River Tributary 2 1.27 1.14 3.16 6.78 4.68 3.63 2.78 3.21 5.04 4.10 6.13 5.02 4.92 5.12 6.423 1 1 Lao PDR Luangprabang Luangprabang Ban Pha O Ban Pha O Mekong River Mainstream 3 3.33 3.63 3.80 3.35 3.03 3.97 2.94 4.07 4.46 3.42 3.82 3.35 3.88 3.69 1.55 3.25 4.40 2.57 3.83 3.27 3.97 3.95 3.14 3.54 3.89 2.36 2.50 2.90 1.88 2.574 1 Lao PDR Borikhamxay Paksan Ban Nam Ngieb Ngieb River Tributary 4 7.16 6.31 8.54 6.57 6.64 7.97 7.52 7.73 5.60 7.27 8.49 7.12 7.43 9.03 3.91 5.99 5.19 6.80 7.84 6.20 5.05 7.305 1 1 Lao PDR Borikhamxay Paksan Ban Xinh Xay Ban Sinhxay Mekong River Mainstream 5 6.07 5.16 7.32 5.91 6.64 6.26 5.55 6.50 6.66 6.14 6.87 8.40 6.10 8.78 4.44 2.49 3.26 2.49 2.99 3.58 0.89 1.69 2.89 4.87 3.93 3.26 4.55 6.09 5.22 4.60 3.81 3.87 3.29 3.31 2.15 2.86 2.686 1 Thailand Nongkhai Sri Chiangmai Pa-sak Mekong River Mainstream 6 1.24 3.03 3.46 1.45 0.79 2.82 2.16 0.83 1.447 1 Thailand Nongkhai Sri Chiangmai Huasai Mekong River Mainstream 7 4.99 5.02 4.02 4.79 2.89 2.40 3.42 3.71 3.95 0.96 1.16 3.61 2.818 1 Thailand Loei Chiangkhan Chiangkhan Chiangkhan Mekong River Mainstream 8 2.34 1.87 2.92 1.60 1.37 0.79 2.50 2.53 1.67 2.69 0.00 0.00 1.52 1.44 1.39 0.61 0.76 0.00 1.79 1.98 1.72 1.82 0.35 0.429 1 Thailand Loei Chiangkhan Noy Noy Mekong River Mainstream 9 1.65 1.12 1.31 0.50 3.41 3.13 2.66 1.14 2.60 2.46 1.64 1.22 1.85 1.79 1.08 1.39 2.50 1.51 1.07 1.60 1.67 2.5110 1 1 Lao PDR Vientiane Hatxayfong Ban Thamuang Ban Thamuang Mekong River Mainstream 10 1.53 1.72 2.73 2.39 2.06 1.93 2.28 2.51 2.21 3.02 2.29 2.72 2.71 2.26 2.39 2.73 2.34 2.81 3.40 3.75 2.66 1.31 0.93 0.91 0.82 1.95 2.29 2.35 2.3911 1 Thailand Nongkhai Tha Bo Donmee Donmee Huai Mong River Tributary 11 0.00 1.56 3.34 3.34 3.66 2.93 2.35 3.08 3.16 2.89 4.83 1.55 3.53 3.45 2.89 2.67 2.00 2.69 1.93 2.49 2.51 2.39 2.8512 1 Thailand Nongkhai Tha Bo Thadang Thadang Huai Mong River Tributary 12 1.24 1.56 3.07 1.90 1.01 2.14 1.86 2.09 2.54 1.32 1.93 2.62 5.01 2.96 2.93 3.11 2.61 2.69 2.42 2.13 0.99 0.56 0.0013 1 Thailand Nakornpanom Sri Songkhram Tha Bo Tha Bo Songkhram River Floodplain 13 6.43 5.64 5.75 2.99 3.21 0.00 2.78 5.08 3.84 3.84 3.50 3.10 2.95 2.35 2.81 1.59 3.72 3.42 1.46 2.1814 1 Thailand Nakornpanom Tha Utain Chaiyaburi Chaiyaburi Mekong River Mainstream 14 1.23 4.53 4.20 2.97 1.64 0.61 0.96 0.53 2.60 2.03 1.89 2.98 2.23 3.40 2.95 2.86 2.26 0.24 0.57 1.60 1.75 0.91 0.9615 1 Lao PDR Khammouane Thakek Ban Mouang Sum Mekong River Mainstream 15 3.37 4.92 4.23 4.86 3.69 4.14 4.68 4.28 4.33 4.44 3.83 3.39 4.72 4.49 2.0716 1 Lao PDR Kham Mouan Tha Ngam Tha Ngam Mekong River Floodplain 1617 1 Thailand Sakolnakorn Phon Nakeaw Phaphang Mekong River Floodplain 17 3.27 2.49 3.22 2.35 3.18 2.92 2.35 2.1918 1 Thailand Sakolnakorn Wang Yam Nongbeung Mekong River Floodplain 18 1.77 2.05 2.38 2.41 2.48 2.10 1.49 2.0719 1 Thailand Nakornphanom Na Keah Pi man thay Mekong River Floodplain 19 1.64 2.12 2.84 4.79 4.65 3.26 4.69 7.52 3.2820 1 Thailand Nakornphanom Tad Phanom Ban Nam Kum Mekong River Mainstream 20 5.45 3.86 1.71 1.53 3.06 1.25 2.72 3.06 3.51 2.38 3.58 3.19 2.3821 1 Thailand Mukdaharn Wan Yai Song-khon Mekong River Mainstream 21 2.85 1.88 1.36 1.41 2.68 2.13 2.31 0.62 1.14 0.75 1.14 2.42 2.2322 1 Thailand Mukdaharn Muang Nalair Mekong River Mainstream 22 0.99 1.03 0.62 1.20 1.54 1.67 2.09 1.12 1.0823 1 Thailand Ubon Ratchathani Khemarat Ladcharoen Ladcharoen Mekong River Mainstream 23 4.55 3.78 3.56 2.18 4.09 4.02 3.61 2.07 2.23 3.32 2.78 1.38 2.76 2.34 1.76 1.37 2.00 2.07 2.35 1.53 5.52 2.87 2.31 1.27 0.9324 1 1 Cambodia Stung Treng Siem Pang Pres Bang Pres Bang Sekong River Tributary 24 1.69 1.19 1.79 4.67 6.65 6.30 7.86 7.36 7.48 7.27 7.22 8.10 7.93 7.04 6.89 5.43 3.88 6.47 4.57 3.89 3.23 3.24 2.69 2.86 3.24 4.48 4.32 3.64 4.97 5.33 5.71 5.87 3.14 10.88 8.75 7.28 8.04 9.10 9.20 7.03 7.55 6.24 4.95 6.53 6.14 6.04 5.60 6.85 6.12 6.95 4.17 7.70 7.15 6.93 8.23 8.22 7.68 7.08 7.88 6.14 5.72 6.01 4.87 4.8825 1 1 Cambodia Ratanakiri Veounsai Banfang Fang Sesan River Tributary 25 1.83 2.36 2.74 2.68 7.22 8.58 8.46 9.02 6.82 7.83 7.03 6.77 6.39 10.53 6.69 6.23 8.43 5.30 3.05 3.60 4.84 4.60 3.21 3.50 3.66 4.80 4.45 5.64 5.47 4.38 4.39 4.45 2.67 6.42 6.65 7.66 7.00 5.31 5.73 5.78 6.57 7.59 7.48 7.75 7.37 7.06 7.23 8.14 6.38 6.58 7.58 5.73 6.97 5.69 6.08 7.88 6.59 5.57 5.84 6.71 6.05 5.01 4.22 4.8826 1 1 Cambodia Stung Treng Talarborivat Ou Run Ou Run Mekong River Mainstream 26 4.56 5.54 5.42 8.97 9.27 9.88 9.81 7.53 8.26 5.40 7.07 7.07 8.47 10.09 7.93 8.83 9.31 7.51 7.16 5.17 7.13 2.26 6.65 4.12 5.83 5.95 5.71 7.43 6.26 5.79 7.19 5.54 5.02 9.02 9.93 9.54 8.07 9.40 9.52 7.50 7.67 6.86 8.37 7.82 7.42 10.90 8.72 8.77 9.52 8.98 7.40 6.88 7.81 8.30 8.40 6.21 5.57 7.52 8.29 10.59 9.51 10.78 12.53 7.0027 1 Cambodia Stung Treng Stung Treng Kang Memai Mekong River Mainstream 27 3.09 4.95 5.29 4.94 10.98 11.75 12.80 11.97 8.18 9.94 9.47 8.53 8.81 8.57 8.74 11.27 11.11 10.54 8.12 3.92 5.94 5.88 6.36 5.34 4.54 5.99 5.91 4.59 6.48 4.39 6.47 5.42 1.8228 1 1 Cambodia Ratanakiri Lum Phat Day Lo Day Lo Srepork River Tributary 28 1.41 1.82 1.49 1.20 9.84 10.13 10.68 8.08 8.06 9.48 10.74 9.14 9.49 9.58 8.12 6.69 7.93 8.27 2.57 4.76 4.04 4.52 3.88 3.81 4.19 4.73 3.64 3.14 4.08 4.79 2.04 2.90 2.42 8.39 10.07 12.14 8.37 8.69 5.65 7.56 7.87 6.97 7.01 8.50 9.30 6.95 5.69 8.56 6.18 7.78 5.89 4.49 4.75 5.22 7.68 7.08 6.32 5.84 8.95 6.74 6.67 6.28 6.20 6.2629 1 Cambodia Stung Treng Sesan Sre Sronok Srepork River Tributary 29 1.60 1.69 1.46 5.68 10.12 12.69 12.13 13.02 10.17 12.36 10.41 11.21 11.39 11.88 11.21 10.09 9.85 10.2830 1 1 Cambodia Kra Tie Sambo Koh Khne Koh khne Mekong River Mainstream 30 5.47 7.23 6.66 7.55 11.92 11.47 10.91 11.63 11.50 11.07 11.78 12.90 13.77 13.64 10.62 12.01 11.17 11.04 5.55 7.28 4.57 7.97 6.83 6.51 5.04 6.21 6.14 7.12 8.09 6.07 5.87 9.07 4.17 8.60 9.04 10.06 10.30 9.62 10.69 9.18 10.82 10.94 12.18 8.99 7.19 8.59 10.22 11.77 9.13 10.54 8.46 11.91 11.29 11.59 12.90 8.52 8.74 9.37 9.74 9.19 10.02 10.26 10.30 9.8031 1 Cambodia Kra Tie Sambo Sandan Mekong River Mainstream 31 2.89 2.10 4.25 4.34 10.51 9.27 8.75 8.36 6.88 6.31 6.41 6.01 5.84 6.50 5.82 7.97 9.11 7.45 6.19 7.51 3.74 4.41 4.47 4.97 4.24 4.96 4.76 4.71 6.45 6.79 4.55 4.75 3.5432 1 Cambodia Kampong Cham Kroch Chmar Pram Mekong River Mainstream 32 2.66 3.05 2.79 2.86 11.62 8.90 8.61 7.79 6.91 5.68 6.34 6.47 5.41 6.03 6.83 5.92 7.78 7.39 7.29 4.94 5.09 4.74 3.73 4.22 4.27 4.31 4.97 4.87 5.24 5.95 6.13 4.58 4.0033 1 Cambodia Kandal Ponhea Leu Peamchumnik Tonle Sap Floodplain 33 12.06 9.33 8.27 7.28 7.63 7.07 5.05 4.40 1.89 2.68 3.14 3.46 3.37 3.8334 1 1 Cambodia Kandal Ponhea Leu Sang Var Sang Var Tonle Sap Tributary 34 6.17 5.72 5.62 5.07 5.70 5.21 5.03 5.43 3.68 4.60 3.61 4.28 3.62 4.52 5.25 5.70 5.45 5.79 5.24 4.32 3.62 4.46 4.40 4.28 3.24 3.25 5.07 2.65 3.40 3.37 3.18 3.56 0.83 8.31 6.47 6.86 7.42 9.21 8.73 6.78 5.56 4.03 6.06 5.03 5.72 4.18 5.05 7.98 8.78 8.07 7.47 7.63 3.67 5.28 5.88 5.42 4.69 4.80 5.42 6.55 7.31 5.09 8.28 4.54 3.1535 1 Cambodia Kandal Sa Ang Baren Tonle Sap Floodplain 35 6.16 5.89 6.15 4.56 9.41 7.66 8.79 9.74 6.29 4.02 3.68 3.81 4.14 3.86 4.86 4.51 4.52 4.12 5.24 4.36 4.07 3.88 3.45 4.31 3.55 3.85 3.51 5.87 5.21 3.86 5.01 4.06 2.9336 1 Cambodia Kandal Leuk Dek Kbal Chroy Mekong River Floodplain 36 1.96 0.97 1.21 0.73 0.73 0.72 1.02 0.93 0.98 0.78 2.04 1.43 0.74 0.94 3.37 2.89 3.29 1.34 0.84 1.23 0.55 0.87 0.29 0.32 0.11 0.34 1.59 1.52 1.25 1.09 1.78 1.38 1.4537 1 Viet Nam An Giang An Phu Phuoc Hung Bassac River Mainstream 37 2.41 4.94 3.70 2.43 5.55 5.71 5.81 4.53 4.26 4.99 3.93 3.91 3.45 2.82 1.43 1.77 2.68 1.79 2.73 3.51 2.71 3.12 3.11 1.94 1.20 2.15 2.29 2.1538 1 Viet Nam An Giang An Phu Ap 2 Ap 2 Bassac River Mainstream 38 1.46 2.10 3.49 2.60 2.05 1.74 2.28 2.65 1.64 1.37 1.04 1.72 1.81 1.95 1.18 1.21 1.46 1.57 2.14 2.22 2.25 2.13 1.90 1.66 2.48 2.66 1.92 1.73 1.89 1.82 2.30 2.17 1.0639 1 Viet Nam Dong Thap Hong Ngu An Binh A Mekong River Mainstream 39 4.02 3.66 3.92 3.44 4.04 3.83 2.64 4.07 3.90 2.83 3.06 3.35 2.89 2.90 3.55 4.76 3.60 2.30 3.61 3.15 3.46 3.22 2.08 3.23 2.31 2.69 2.01 2.2740 1 Viet Nam Dong Thap Tam Nong Phu Duc Mekong River Floodplain 40 4.73 3.94 3.03 1.36 3.17 2.50 3.06 1.85 1.60 1.65 1.81 1.92 2.11 1.95 2.25 2.71 3.70 4.36 3.02 2.33 2.59 2.38 3.26 2.48 2.72 3.28 4.04 3.15 3.73 3.2741 1 Viet Nam An Giang Cho Moi My Thuan My Thuan Bassac River Mainstream 41 1.46 1.49 1.76 0.95 2.28 2.35 1.82 6.39 7.38 6.81 6.47 6.22 5.84 5.45 5.20 5.48 5.44 1.72 1.81 4.52 3.54 2.6242 1 Viet Nam An Giang Phu Tan Vam Nao Vam Nao Vam Nao canal Tributary 42 0.57 0.40 1.83 2.54 2.21 2.36 2.74 2.23 1.90 2.03 2.16 1.52 1.04 1.12 2.84 5.03 5.85 3.70 4.32 4.39 4.09 4.88 4.85 3.65 2.55 3.01 3.02 3.96 3.16 1.0843 1 Viet Nam Dong Thap An Phu Thap Muoi Mekong River Floodplain 43 3.03 1.80 2.01 2.91 2.99 2.55 1.61 2.07 2.24 2.14 2.35 1.76 1.9944 1 Viet Nam An Giang Tri Ton An Tuc Mekong River Floodplain 44 0.70 2.43 1.69 2.36 2.13 2.32 2.00 1.27 1.25 1.23 1.24 1.72 1.87 1.33 1.82 2.42 2.27 1.16 1.45 1.69 1.68 1.39 1.00 0.95 2.57 2.29 3.01 1.7145 1 Viet Nam Tien Giang Chau Thanh Kim Son Mekong River Mainstream 45 4.98 3.93 2.51 2.52 3.50 2.30 2.61 2.41 3.09 1.36 4.42 2.73 3.5746 1 Viet Nam Tien Giang Go Cong Tay Phu Thanh Mekong River Mainstream 46 1.96 3.59 2.94 6.34 5.59 5.04 4.86 4.73 4.48 4.19 4.18 4.31 4.64 4.41 4.23 3.92 5.50 5.35 5.01 4.46 4.99 3.22 4.65 3.24 3.79 4.20 3.73 3.73 4.15 5.45 4.1847 1 Viet Nam Vinh Long TX Vinh Long 39/9A Tran Phu Mekong River Mainstream 47 1.99 2.48 3.56 2.08 1.61 2.71 3.16 2.08 2.03 1.63 2.06 1.5548 1 1 Viet Nam An Giang Thoai Son Tay Son Tay Son Bassac River Floodplain 48 0.41 1.05 0.72 0.90 0.65 1.08 1.86 1.34 0.95 1.31 0.58 0.49 0.97 0.97 1.87 2.24 1.77 1.67 1.98 2.60 2.88 2.57 2.25 1.95 1.85 2.31 2.58 1.13 1.64 1.74 1.67 1.87 2.28 2.30 2.54 2.00 2.00 2.48 1.49 1.99 1.90 1.79 1.92 2.46 2.28 2.02 1.4449 1 Viet Nam Vinh Long Vung Liem Thanh Binh Mekong River Mainstream 49 0.16 2.26 2.16 2.57 1.76 2.33 3.38 2.62 2.14 2.04 1.15 1.61 1.39 1.37 1.04 1.20 0.93 1.42 1.62 0.77 0.83 0.75 0.76 0.82 0.91 1.50 1.33 1.16 1.05 0.88 0.8150 1 Viet Nam Vinh Long Vung Liem Lang Lang Mekong River Mainstream 50 1.39 1.32 1.03 1.16 1.52 1.50 1.85 1.94 1.82 1.75 1.91 1.80 1.92 1.88 2.41 2.01 1.46 1.91 2.13 2.04 2.37 2.20 1.97 1.78 1.83 1.71 1.61 1.75 1.78 1.72 1.62 1.94 1.7851 1 Viet Nam Vinh Long Tra On Khu 9 Bassac River Mainstream 51 1.04 2.52 1.38 1.94 1.02 1.69 1.53 1.13 2.13 1.46 1.46 1.90 1.94 1.98 1.5752 1 Viet Nam Tra Vinh Chau Thanh Dai Thon Mekong River Mainstream 52 2.18 1.57 1.83 1.28 1.33 2.22 2.61 2.39 2.12 2.25 2.0353 1 Viet Nam Tra Vinh Tieu Can Khom Dinh Bassac River Mainstream 53 1.60 5.57 4.37 5.26 3.70 4.70 5.20 5.26 4.35 3.61 4.53 4.21 4.18 4.21 4.29 5.84 7.04 5.62 6.88 5.91 7.08 4.32 3.96 4.22 4.23 4.69 4.17 4.47 4.6954 1 Viet Nam Tra Vinh Tieu Can Khom 3 Khom 3 Bassac River Estuary 54 2.01 1.93 1.83 1.51 2.13 3.34 2.11 1.36 1.19 1.42 1.62 2.14 2.22 2.16 2.90 2.99 2.71 3.49 2.61 2.24 2.14 3.22 1.69 2.01 1.66 2.10 2.33 2.41 2.40 3.57 2.61 2.59 0.49

Table 25 MonthlyestimatesoftheMargalefindexatthefishercatchmonitoringsites(2003–2010).


VILLAGE NAME 2003 2004 2005 2007 2008 2009 2010

Site AMCF FEVM Country Province District AMCF FEVM River Name Habitat Type Order 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 21 1 Lao PDR Bokeo Houixay Ban Done Mekong River Mainstream 1 1.67 13.58 8.14 7.80 7.30 7.04 7.45 7.07 7.28 7.53 7.35 6.32 7.94 6.92 2.33 2.70 2.62 1.472 1 Lao PDR Luangprabang Ban Hat Ya Ban Hat Gna Ou River Tributary 2 2.44 1.97 4.47 7.57 5.35 4.01 3.13 3.88 6.68 6.22 8.85 7.64 7.54 7.09 7.333 1 1 Lao PDR Luangprabang Luangprabang Ban Pha O Ban Pha O Mekong River Mainstream 3 6.24 5.59 5.88 5.56 5.58 7.13 5.09 6.61 7.21 5.26 5.87 5.79 6.75 5.82 2.70 4.10 4.50 2.56 3.75 3.25 5.45 5.43 3.96 4.83 5.78 3.76 3.33 3.99 2.43 3.564 1 Lao PDR Borikhamxay Paksan Ban Nam Ngieb Ngieb River Tributary 4 14.30 11.10 15.35 12.00 12.18 13.11 11.82 13.05 11.62 11.19 13.70 12.47 13.01 13.90 6.60 8.40 6.99 8.82 10.48 8.23 6.70 9.415 1 1 Lao PDR Borikhamxay Paksan Ban Xinh Xay Ban Sinhxay Mekong River Mainstream 5 9.70 9.25 11.39 9.18 10.16 10.42 8.95 9.56 9.61 8.95 9.82 11.67 8.60 12.86 7.28 4.80 5.53 5.00 6.41 7.06 2.04 3.30 4.20 6.43 5.15 4.66 6.07 7.80 6.49 5.73 5.33 5.56 5.54 4.78 3.10 3.98 3.566 1 Thailand Nongkhai Sri Chiangmai Pa-sak Mekong River Mainstream 6 2.17 3.00 6.34 3.68 2.58 3.85 2.23 0.89 1.027 1 Thailand Nongkhai Sri Chiangmai Huasai Mekong River Mainstream 7 8.22 7.22 4.63 8.86 3.60 5.00 7.48 6.87 4.98 1.30 3.61 3.53 3.388 1 Thailand Loei Chiangkhan Chiangkhan Chiangkhan Mekong River Mainstream 8 3.37 1.92 3.91 2.85 2.70 1.27 4.19 3.24 1.84 2.83 0.27 0.26 1.64 2.18 2.04 1.30 1.30 0.42 2.62 2.75 2.12 2.02 0.56 0.679 1 Thailand Loei Chiangkhan Noy Noy Mekong River Mainstream 9 2.55 1.99 1.78 0.87 4.70 5.48 5.76 2.38 5.96 6.99 3.00 2.40 1.94 2.97 2.92 3.11 5.00 3.64 2.97 4.25 2.94 5.2910 1 1 Lao PDR Vientiane Hatxayfong Ban Thamuang Ban Thamuang Mekong River Mainstream 10 3.37 3.30 5.14 4.63 4.30 3.71 4.12 4.10 3.75 4.50 3.62 4.24 4.12 3.80 3.14 3.10 2.58 2.85 3.11 4.02 2.88 1.58 1.79 1.78 1.55 2.22 2.23 2.00 2.6711 1 Thailand Nongkhai Tha Bo Donmee Donmee Huai Mong River Tributary 11 0.91 2.91 6.76 8.94 11.68 11.38 10.23 6.46 6.97 9.13 11.10 6.25 13.22 15.15 10.01 7.15 5.77 7.97 6.15 8.01 7.77 8.85 8.7212 1 Thailand Nongkhai Tha Bo Thadang Thadang Huai Mong River Tributary 12 2.53 3.49 6.35 5.09 2.45 6.73 4.20 4.75 6.61 3.32 4.37 6.34 10.43 6.86 7.22 7.42 5.62 6.08 5.97 4.47 2.13 1.25 0.3013 1 Thailand Nakornpanom Sri Songkhram Tha Bo Tha Bo Songkhram River Floodplain 13 10.84 10.09 13.18 8.51 6.81 0.48 4.96 10.59 7.96 7.50 7.33 8.58 7.54 5.12 7.15 4.04 8.69 8.10 3.23 6.0614 1 Thailand Nakornpanom Tha Utain Chaiyaburi Chaiyaburi Mekong River Mainstream 14 1.89 5.49 4.18 3.06 1.33 0.88 0.88 0.67 4.19 3.78 3.07 3.09 1.10 2.43 3.34 4.43 3.38 0.50 0.97 3.23 3.16 1.09 1.5415 1 Lao PDR Khammouane Thakek Ban Mouang Sum Mekong River Mainstream 15 6.13 9.38 7.63 8.00 6.11 8.29 7.53 6.87 8.08 5.92 5.22 5.59 7.14 6.68 3.4916 1 Lao PDR Kham Mouan Tha Ngam Tha Ngam Mekong River Floodplain 1617 1 Thailand Sakolnakorn Phon Nakeaw Phaphang Mekong River Floodplain 17 6.70 5.58 6.91 4.67 6.01 5.29 5.03 4.9318 1 Thailand Sakolnakorn Wang Yam Nongbeung Mekong River Floodplain 18 6.21 4.68 4.66 5.03 5.29 4.31 3.73 4.7219 1 Thailand Nakornphanom Na Keah Pi man thay Mekong River Floodplain 19 5.77 5.68 5.98 9.85 9.41 7.71 9.72 16.69 11.1820 1 Thailand Nakornphanom Tad Phanom Ban Nam Kum Mekong River Mainstream 20 11.56 7.42 3.61 3.91 6.84 2.89 5.91 7.08 8.20 5.70 6.90 6.96 6.0921 1 Thailand Mukdaharn Wan Yai Song-khon Mekong River Mainstream 21 6.95 4.11 4.22 4.34 3.15 3.24 6.24 7.21 2.49 2.06 2.34 4.60 3.6422 1 Thailand Mukdaharn Muang Nalair Mekong River Mainstream 22 1.52 7.21 1.25 1.62 1.92 2.01 2.91 1.62 1.4823 1 Thailand Ubon Ratchathani Khemarat Ladcharoen Ladcharoen Mekong River Mainstream 23 4.98 3.81 3.58 2.27 3.45 5.01 3.55 3.64 2.22 3.37 2.85 1.49 2.86 2.26 1.86 1.31 1.84 1.97 2.05 3.03 6.71 3.27 2.25 1.33 1.2624 1 1 Cambodia Stung Treng Siem Pang Pres Bang Pres Bang Sekong River Tributary 24 2.96 2.12 3.83 8.39 11.59 11.74 14.37 14.05 13.16 13.23 13.52 15.04 15.02 13.02 12.74 10.67 7.49 12.28 9.90 8.70 6.38 6.47 5.54 7.46 7.06 10.29 9.90 7.86 10.44 11.58 11.58 12.18 8.22 16.37 14.00 11.90 13.84 15.57 14.26 9.93 11.46 10.78 7.81 11.37 9.87 9.20 9.42 11.84 9.98 10.43 6.92 12.59 10.45 10.99 12.55 13.43 12.37 12.20 13.27 10.62 10.05 10.69 8.62 8.4225 1 1 Cambodia Ratanakiri Veounsai Banfang Fang Sesan River Tributary 25 3.56 4.75 5.67 5.91 12.09 14.11 14.42 14.40 11.81 12.97 12.05 12.16 11.53 20.41 12.79 10.19 12.74 10.42 6.75 7.02 9.75 9.44 8.21 7.65 8.47 10.44 9.44 11.16 10.07 8.39 10.56 8.29 6.68 12.92 12.16 13.87 12.98 10.10 10.19 10.70 12.52 13.77 13.46 13.73 14.09 11.80 11.38 13.43 12.48 11.78 13.19 9.70 11.89 10.52 10.72 14.22 11.56 9.10 10.08 11.55 10.48 8.61 8.04 8.7926 1 1 Cambodia Stung Treng Talarborivat Ou Run Ou Run Mekong River Mainstream 26 8.09 9.70 8.29 13.96 13.97 13.58 14.18 10.94 12.62 8.18 13.73 13.73 14.50 16.25 14.63 14.29 12.92 11.28 9.60 6.75 11.10 5.77 11.32 8.15 10.53 10.20 9.75 11.07 10.80 8.29 9.51 7.50 9.14 17.95 15.77 14.92 12.55 14.61 13.78 10.25 13.21 12.74 15.40 15.47 12.77 15.90 11.55 12.95 14.52 14.01 9.48 8.75 11.15 17.13 16.30 13.96 12.29 15.72 14.23 16.79 15.38 15.87 17.70 9.5427 1 Cambodia Stung Treng Stung Treng Kang Memai Mekong River Mainstream 27 7.34 11.88 11.97 9.50 17.54 17.69 21.45 17.60 12.86 14.64 18.77 18.00 19.05 17.24 14.33 17.34 17.20 16.26 15.44 6.47 10.19 13.82 15.61 13.23 11.66 16.17 12.74 8.23 12.05 9.10 12.30 8.2928 1 1 Cambodia Ratanakiri Lum Phat Day Lo Day Lo Srepork River Tributary 28 2.87 3.24 2.59 2.20 15.65 16.08 17.20 12.12 11.57 15.25 18.93 16.54 16.44 16.45 13.66 10.42 12.09 12.19 4.50 9.94 9.57 10.68 8.19 6.57 7.55 9.60 7.23 5.94 7.55 9.11 4.30 6.07 6.17 12.35 15.06 18.97 12.85 14.60 8.64 12.14 11.21 11.10 11.24 13.09 14.39 10.72 8.58 13.03 10.95 12.05 8.84 7.11 7.95 9.48 12.90 11.47 10.06 9.48 14.11 10.15 11.07 10.63 9.66 9.5429 1 Cambodia Stung Treng Sesan Sre Sronok Srepork River Tributary 29 3.30 3.30 2.87 9.90 17.22 21.78 21.95 21.38 15.96 19.81 17.83 19.17 20.01 20.71 19.97 17.59 16.39 18.5530 1 1 Cambodia Kra Tie Sambo Koh Khne Koh khne Mekong River Mainstream 30 12.44 15.73 10.58 12.23 20.15 18.22 18.97 19.33 18.63 18.96 18.77 22.12 23.08 23.96 18.00 19.78 17.11 16.86 11.17 12.35 6.99 15.60 12.77 12.05 15.04 14.85 16.46 14.11 13.40 10.29 11.07 17.35 10.86 17.15 12.64 14.00 13.43 14.70 16.83 13.48 15.58 15.52 18.23 16.47 13.52 13.74 13.74 16.68 13.59 14.73 13.21 17.67 17.15 18.10 19.71 15.32 15.93 12.68 13.21 12.68 14.52 15.12 14.28 14.4331 1 Cambodia Kra Tie Sambo Sandan Mekong River Mainstream 31 2.12 2.76 8.50 7.06 16.83 16.48 16.07 14.42 12.22 11.26 13.03 13.18 13.62 14.12 13.61 16.16 17.30 14.71 13.52 14.85 9.85 11.76 12.89 13.50 12.43 12.90 13.67 13.40 15.15 15.15 9.00 9.11 8.3732 1 Cambodia Kampong Cham Kroch Chmar Pram Mekong River Mainstream 32 4.66 5.10 3.67 3.30 18.24 17.60 18.01 15.75 13.96 11.05 13.48 14.45 12.52 13.16 12.74 11.71 14.90 17.67 18.07 12.59 13.66 13.04 9.51 11.33 11.31 11.03 12.73 13.23 13.79 15.26 15.15 11.69 13.3433 1 Cambodia Kandal Ponhea Leu Peamchumnik Tonle Sap Floodplain 33 19.82 17.88 17.20 14.78 14.71 13.92 9.78 9.09 4.03 5.42 6.17 6.81 7.11 8.9134 1 1 Cambodia Kandal Ponhea Leu Sang Var Sang Var Tonle Sap Tributary 34 10.80 9.03 6.75 8.32 10.80 10.18 10.88 12.89 8.80 10.74 8.59 10.03 8.21 8.82 10.74 10.58 10.74 12.05 11.18 8.91 7.57 10.92 10.35 9.32 7.13 7.20 11.70 5.59 6.76 8.32 7.80 6.53 2.16 13.65 11.51 11.99 13.44 14.65 14.26 12.08 13.25 10.22 11.78 9.24 10.21 8.24 9.73 13.77 15.42 12.43 11.69 13.43 10.33 13.22 10.11 9.06 8.00 8.28 9.58 12.22 12.73 11.58 13.58 12.58 10.1435 1 Cambodia Kandal Sa Ang Baren Tonle Sap Floodplain 35 8.59 9.57 9.75 7.24 12.28 12.82 14.59 13.48 9.24 8.24 8.34 9.36 10.39 9.42 11.24 8.62 10.02 10.43 13.29 10.97 10.51 9.51 9.23 10.91 9.31 9.76 8.77 11.11 12.20 9.93 12.08 10.77 12.2836 1 Cambodia Kandal Leuk Dek Kbal Chroy Mekong River Floodplain 36 3.64 2.06 2.38 1.46 1.46 1.35 1.83 1.81 1.85 1.42 3.18 3.08 1.67 2.02 6.31 5.01 5.31 2.50 1.76 2.48 1.23 1.77 0.79 0.99 0.50 0.99 3.48 2.70 2.24 2.08 3.16 2.71 4.1037 1 Viet Nam An Giang An Phu Phuoc Hung Bassac River Mainstream 37 14.10 10.50 7.72 17.47 17.05 16.33 13.71 12.00 13.52 10.80 11.68 9.30 9.10 5.19 5.64 8.93 6.63 8.23 9.60 8.35 8.23 8.40 8.37 4.42 7.23 7.34 7.2138 1 Viet Nam An Giang An Phu Ap 2 Ap 2 Bassac River Mainstream 38 4.11 5.84 8.39 6.43 4.82 4.06 5.53 5.73 3.39 2.57 2.23 3.10 3.15 4.14 2.94 3.11 3.55 3.82 4.88 4.07 4.29 3.91 3.31 2.91 4.93 5.69 4.68 4.30 4.43 4.22 3.99 4.01 3.3539 1 Viet Nam Dong Thap Hong Ngu An Binh A Mekong River Mainstream 39 11.81 11.36 14.19 11.65 13.96 12.94 9.80 13.20 12.18 8.70 10.38 16.38 10.70 11.35 12.05 15.43 13.36 13.67 12.18 10.88 12.05 10.70 6.98 11.10 8.53 9.41 7.06 8.6640 1 Viet Nam Dong Thap Tam Nong Phu Duc Mekong River Floodplain 40 29.13 10.84 8.02 12.62 10.00 11.76 7.15 5.90 5.91 6.49 8.74 6.60 5.76 6.68 9.63 13.07 15.65 10.32 6.98 8.01 7.47 9.89 7.46 8.39 9.80 12.18 10.88 12.35 10.8841 1 Viet Nam An Giang Cho Moi My Thuan My Thuan Bassac River Mainstream 41 3.27 3.30 4.15 4.17 6.58 6.63 5.73 14.40 15.78 14.05 12.70 12.11 11.47 10.88 10.29 10.79 13.13 5.17 5.42 9.70 7.30 10.5642 1 Viet Nam An Giang Phu Tan Vam Nao Vam Nao Vam Nao canal Tributary 42 3.64 2.23 5.01 6.87 5.96 6.22 5.78 3.74 2.28 2.44 4.96 4.37 2.65 3.23 7.97 11.20 10.10 6.80 7.44 8.25 8.04 9.51 9.15 7.05 5.70 6.79 6.91 8.05 6.09 3.8543 1 Viet Nam Dong Thap An Phu Thap Muoi Mekong River Floodplain 43 15.87 9.32 5.82 6.76 9.61 10.00 8.74 5.64 6.83 7.06 6.83 7.35 5.64 6.2444 1 Viet Nam An Giang Tri Ton An Tuc Mekong River Floodplain 44 6.21 4.37 8.87 7.06 8.23 6.70 4.55 4.53 4.08 4.16 5.35 8.18 4.04 5.74 7.42 9.36 10.10 5.76 5.88 6.57 4.66 3.56 4.81 8.32 7.64 10.29 7.2145 1 Viet Nam Tien Giang Chau Thanh Kim Son Mekong River Mainstream 45 14.16 13.03 9.38 8.87 11.64 13.67 13.65 11.45 12.29 17.31 18.68 18.76 20.2046 1 Viet Nam Tien Giang Go Cong Tay Phu Thanh Mekong River Mainstream 46 21.64 10.39 8.91 17.11 13.96 14.16 13.50 13.05 12.59 12.23 12.56 12.80 13.05 12.43 11.97 11.35 15.77 15.31 14.03 12.62 14.12 9.35 13.34 10.06 11.45 15.93 10.87 11.76 12.57 16.30 14.0947 1 Viet Nam Vinh Long TX Vinh Long 39/9A Tran Phu Mekong River Mainstream 47 7.27 9.71 5.90 4.37 7.06 8.15 5.35 6.00 4.95 6.47 4.9748 1 1 Viet Nam An Giang Thoai Son Tay Son Tay Son Bassac River Floodplain 48 4.33 2.65 1.78 2.73 2.08 3.00 4.30 4.02 2.80 3.73 1.84 1.70 2.87 2.80 5.43 5.23 4.40 4.30 4.90 6.06 6.60 5.72 5.31 4.50 4.40 5.16 5.67 3.12 4.16 4.29 4.07 4.36 5.23 5.33 5.61 4.77 4.97 6.10 3.68 4.83 4.69 4.51 4.91 5.69 4.98 4.60 6.8349 1 Viet Nam Vinh Long Vung Liem Thanh Binh Mekong River Mainstream 49 6.30 5.64 7.20 5.05 6.47 10.44 8.73 7.12 7.96 3.99 5.52 4.85 4.91 3.78 4.30 3.42 4.85 5.40 2.87 3.62 2.62 2.91 2.94 3.46 5.42 4.60 4.50 3.78 3.28 7.2850 1 Viet Nam Vinh Long Vung Liem Lang Lang Mekong River Mainstream 50 3.94 3.35 2.57 2.78 3.33 3.42 4.06 4.21 4.03 3.80 4.29 4.01 4.32 4.07 5.28 4.43 3.15 4.16 4.71 4.30 4.78 4.56 4.54 4.24 4.28 3.95 3.59 3.96 3.68 3.90 3.61 4.1151 1 Viet Nam Vinh Long Tra On Khu 9 Bassac River Mainstream 51 6.53 3.64 5.70 3.30 5.50 5.46 4.15 7.06 5.40 5.10 6.75 6.68 6.37 5.4152 1 Viet Nam Tra Vinh Chau Thanh Dai Thon Mekong River Mainstream 52 5.50 3.99 5.52 4.16 4.35 6.70 7.89 7.20 6.47 7.13 7.5753 1 Viet Nam Tra Vinh Tieu Can Khom Dinh Bassac River Mainstream 53 15.87 15.47 12.62 17.19 12.76 20.12 17.94 19.84 17.71 21.13 15.73 17.05 24.23 17.93 17.75 22.53 23.16 19.26 23.92 19.30 20.71 17.93 17.30 17.30 18.66 17.31 16.25 19.54 22.7654 1 Viet Nam Tra Vinh Tieu Can Khom 3 Khom 3 Bassac River Estuary 54 5.74 4.93 4.57 3.65 4.94 7.82 5.03 3.28 3.09 3.58 4.04 4.75 5.01 4.95 6.46 6.92 6.76 7.72 5.85 4.95 4.82 7.25 3.92 4.55 3.75 4.67 5.10 5.38 5.66 7.83 5.73 5.64

Table 26 Monthlyestimatesofthespeciesrichnessindex(SRI)atthefishercatchmonitoringsites(2003–2010).

VILLAGE NAME 2003 2004 2005 2007 2008 2009 2010

Site AMCF FEVM Country Province District AMCF FEVM River Name Habitat Type Order 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 21 1 Lao PDR Bokeo Houixay Ban Done Mekong River Mainstream 1 1 43 768 357 455 393 980 578 933 683 662 3696 3153 2179 415 543 1235 12982 1 Lao PDR Luangprabang Ban Hat Ya Ban Hat Gna Ou River Tributary 2 13 8 4 1 2 1 1 2 4 8 6 8 9 5 23 1 1 Lao PDR Luangprabang Luangprabang Ban Pha O Ban Pha O Mekong River Mainstream 3 25 8 8 13 27 22 13 11 10 8 8 15 21 6 6 2 1 1 1 1 4 4 2 4 7 10 3 4 2 44 1 Lao PDR Borikhamxay Paksan Ban Nam Ngieb Ngieb River Tributary 4 33 21 17 17 14 10 8 17 85 9 12 22 23 9 8 3 3 2 3 3 3 25 1 1 Lao PDR Borikhamxay Paksan Ban Xinh Xay Ban Sinhxay Mekong River Mainstream 5 6 17 9 9 9 15 12 6 6 6 5 5 5 7 7 15 8 21 36 21 28 13 5 3 3 5 4 3 3 3 5 5 16 5 5 4 36 1 Thailand Nongkhai Sri Chiangmai Pa-sak Mekong River Mainstream 6 3 1 9 75 127 2 1 0 07 1 Thailand Nongkhai Sri Chiangmai Huasai Mekong River Mainstream 7 8 4 1 17 2 26 55 22 2 1 8 1 18 1 Thailand Loei Chiangkhan Chiangkhan Chiangkhan Mekong River Mainstream 8 4 1 3 15 24 3 10 2 1 1 0 0 1 3 2 3 1 0 3 3 1 1 0 19 1 Thailand Loei Chiangkhan Noy Noy Mekong River Mainstream 9 3 6 2 2 3 10 32 16 65 372 7 11 1 5 23 17 20 54 154 189 7 2910 1 1 Lao PDR Vientiane Hatxayfong Ban Thamuang Ban Thamuang Mekong River Mainstream 10 6 16 21 25 45 32 22 9 9 6 8 7 6 9 2 1 1 1 1 1 1 1 22 24 17 1 1 0 111 1 Thailand Nongkhai Tha Bo Donmee Donmee Huai Mong River Tributary 11 2 10 24 249 541 404 4649 42 79 674 62 294 4553 8964 1147 151 155 323 505 518 257 549 16112 1 Thailand Nongkhai Tha Bo Thadang Thadang Huai Mong River Tributary 12 18 77 58 605 130 54 39 46 110 113 46 48 47 73 172 77 51 80 186 53 27 22 3413 1 Thailand Nakornpanom Sri Songkhram Tha Bo Tha Bo Songkhram River Floodplain 13 14 24 407 2724 73 1 1 27 91 86 58 105 2207 784 130 191 166 141 139 45 30714 1 Thailand Nakornpanom Tha Utain Chaiyaburi Chaiyaburi Mekong River Mainstream 14 4 2 1 1 0 1 0 1 11 30 10 1 0 0 1 8 5 1 3 33 16 1 115 1 Lao PDR Khammouane Thakek Ban Mouang Sum Mekong River Mainstream 15 18 35 19 13 11 54 12 11 34 3 4 12 7 7 716 1 Lao PDR Kham Mouan Tha Ngam Tha Ngam Mekong River Floodplain 1617 1 Thailand Sakolnakorn Phon Nakeaw Phaphang Mekong River Floodplain 17 27 29 55 24 16 15 24 2818 1 Thailand Sakolnakorn Wang Yam Nongbeung Mekong River Floodplain 18 32 17 14 21 32 31 215 3619 1 Thailand Nakornphanom Na Keah Pi man thay Mekong River Floodplain 19 18 53 24 20 24 10 34 49 3520 1 Thailand Nakornphanom Tad Phanom Ban Nam Kum Mekong River Mainstream 20 59 22 16 19 16 17 44 159 163 68 29 84 18221 1 Thailand Mukdaharn Wan Yai Song-khon Mekong River Mainstream 21 19 6 839 247 1 3 116 327 3 8 6 10 322 1 Thailand Mukdaharn Muang Nalair Mekong River Mainstream 22 2 25 2 1 1 1 2 2 123 1 Thailand Ubon Ratchathani Khemarat Ladcharoen Ladcharoen Mekong River Mainstream 23 1 1 1 1 0 3 1 17 1 1 1 1 1 1 1 0 0 1 0 47 2 1 1 1 124 1 1 Cambodia Stung Treng Siem Pang Pres Bang Pres Bang Sekong River Tributary 24 5 6 20 10 16 39 28 37 23 28 37 32 35 38 34 58 46 41 44 41 15 22 12 125 34 66 59 40 29 43 27 32 17 9 12 14 21 21 9 5 8 15 8 15 9 7 11 16 9 6 8 11 5 10 8 14 10 19 16 20 21 24 20 1825 1 1 Cambodia Ratanakiri Veounsai Banfang Fang Sesan River Tributary 25 11 20 17 18 13 15 19 12 20 16 18 23 21 49 33 11 8 54 37 15 20 23 84 31 32 37 28 18 12 15 74 13 13 50 20 25 30 23 19 30 40 30 29 26 45 17 10 17 62 30 27 18 21 40 34 33 25 16 22 30 32 25 56 3426 1 1 Cambodia Stung Treng Talarborivat Ou Run Ou Run Mekong River Mainstream 26 9 11 4 6 7 5 7 7 9 7 35 41 20 14 38 14 5 6 3 2 6 6 8 14 9 9 8 5 10 3 3 3 5 97 14 13 9 10 7 5 22 37 56 83 31 8 4 9 10 13 3 3 6 113 95 309 251 194 27 16 19 9 7 527 1 Cambodia Stung Treng Stung Treng Kang Memai Mekong River Mainstream 27 54 91 51 18 12 9 20 8 10 7 66 103 142 81 15 10 11 9 18 6 10 83 108 126 133 274 38 12 16 27 17 5 328 1 1 Cambodia Ratanakiri Lum Phat Day Lo Day Lo Srepork River Tributary 28 13 6 5 6 10 13 14 8 6 13 25 25 21 23 19 10 9 7 8 27 57 54 13 6 10 25 15 15 12 18 23 26 13 8 8 12 9 23 11 17 6 13 14 10 12 10 8 10 20 12 9 12 14 26 20 14 13 16 14 9 18 24 13 1129 1 Cambodia Stung Treng Sesan Sre Sronok Srepork River Tributary 29 19 13 11 10 15 22 35 16 12 13 20 21 23 25 29 22 17 2430 1 1 Cambodia Kra Tie Sambo Koh Khne Koh khne Mekong River Mainstream 30 56 49 6 7 18 13 26 18 15 19 12 22 18 27 21 17 10 9 26 9 5 26 16 16 522 101 260 24 8 9 18 20 31 92 5 6 4 10 13 9 8 6 8 29 33 13 4 6 8 6 11 9 10 12 12 36 43 5 5 5 7 9 6 831 1 Cambodia Kra Tie Sambo Sandan Mekong River Mainstream 31 0 2 19 7 11 27 36 21 27 24 67 134 203 126 251 86 42 36 48 23 110 98 370 221 394 132 332 451 80 54 21 18 932 1 Cambodia Kampong Cham Kroch Chmar Pram Mekong River Mainstream 32 8 7 2 1 10 68 113 77 80 51 109 171 265 156 39 60 51 374 371 382 719 756 315 643 481 403 331 697 551 399 320 314 50133 1 Cambodia Kandal Ponhea Leu Peamchumnik Tonle Sap Floodplain 33 11 34 76 57 39 46 28 49 53 43 31 40 68 6734 1 1 Cambodia Kandal Ponhea Leu Sang Var Sang Var Tonle Sap Tributary 34 10 6 2 7 17 15 43 73 74 62 68 50 36 20 25 16 20 33 32 28 32 94 52 45 41 42 64 29 22 104 92 13 3 16 31 30 41 13 15 25 396 577 76 37 27 62 54 22 29 11 11 28 2074 858 32 15 19 27 28 42 24 252 16 2432 21335 1 Cambodia Kandal Sa Ang Baren Tonle Sap Floodplain 35 3 6 5 5 3 16 15 5 6 59 133 282 475 352 177 36 133 372 268 264 322 190 247 289 336 307 212 23 116 197 176 362 21736 1 Cambodia Kandal Leuk Dek Kbal Chroy Mekong River Floodplain 36 10 16 11 8 16 12 12 21 17 9 6 45 50 56 31 15 9 15 23 27 24 19 23 203 125 133 65 12 10 13 14 24 2837 1 Viet Nam An Giang An Phu Phuoc Hung Bassac River Mainstream 37 220 395 353 1014 1322 719 376 464 339 273 262 296 215 1092 966 916 1016 601 655 246 346 189 211 231 1130 829 643 43738 1 Viet Nam An Giang An Phu Ap 2 Ap 2 Bassac River Mainstream 38 17 44 189 524 287 208 408 89 62 21 23 21 16 80 315 497 327 313 197 26 36 24 14 16 54 102 372 392 261 221 18 28 1939 1 Viet Nam Dong Thap Hong Ngu An Binh A Mekong River Mainstream 39 400 1055 1482 2707 3009 2488 6223 1402 971 696 719 3859 3769 4372 2631 1799 7066 1842 2230 3105 3526 1192 1437 2449 5983 3394 3160 159340 1 Viet Nam Dong Thap Tam Nong Phu Duc Mekong River Floodplain 40 233 159 185 173 2819 17870 11291 6021 2972 1405 737 588 738 372 417 2524 3850 3668 2031 468 361 354 428 422 563 595 682 3013 1987 203541 1 Viet Nam An Giang Cho Moi My Thuan My Thuan Bassac River Mainstream 41 32 29 29 2715 2645 2501 4645 190 147 109 94 92 93 98 88 89 311 1969 1848 206 124 9042 1 Viet Nam An Giang Phu Tan Vam Nao Vam Nao Vam Nao canal Tributary 42 67 308 615 1457 1395 1011 101 14 1 2 91 324 75 248 507 219 20 21 26 51 95 89 77 101 551 676 724 195 96 8443 1 Viet Nam Dong Thap An Phu Thap Muoi Mekong River Floodplain 43 905 1204 1882 1930 2050 2858 2396 1453 969 991 900 965 81044 1 Viet Nam An Giang Tri Ton An Tuc Mekong River Floodplain 44 1212 101 125 2884 1651 3695 1945 2194 1451 1227 1204 673 665 323 492 704 1901 18098 8931 2490 2518 1537 1994 1608 1249 1872 2701 415145 1 Viet Nam Tien Giang Chau Thanh Kim Son Mekong River Mainstream 45 285 161 1332 1469 1215 1866 7462 17131 7090 1591 8978 2338 48546 1 Viet Nam Tien Giang Go Cong Tay Phu Thanh Mekong River Mainstream 46 632 450 671 245 129 257 268 266 254 224 179 236 277 275 226 227 243 282 231 229 217 216 144 136 182 182 214 382 309 295 28347 1 Viet Nam Vinh Long TX Vinh Long 39/9A Tran Phu Mekong River Mainstream 47 153 178 225 229 195 163 167 120 407 593 882 63648 1 1 Viet Nam An Giang Thoai Son Tay Son Tay Son Bassac River Floodplain 48 69 66 37 270 332 144 41 69 189 173 209 182 163 150 158 229 344 576 452 202 203 145 182 201 227 157 107 38 412 374 308 197 195 151 119 198 233 206 135 225 422 488 464 214 121 158 21049 1 Viet Nam Vinh Long Vung Liem Thanh Binh Mekong River Mainstream 49 530 247 145 275 303 274 667 939 834 1302 1283 1517 1743 2192 1633 1898 1964 1391 1314 1494 1300 1433 1651 1934 2470 1841 1412 1742 1448 1332 179650 1 Viet Nam Vinh Long Vung Liem Lang Lang Mekong River Mainstream 50 130 116 131 108 76 99 116 119 96 108 146 139 144 104 119 104 88 98 139 82 57 70 192 202 165 157 126 125 60 138 124 79 2951 1 Viet Nam Vinh Long Tra On Khu 9 Bassac River Mainstream 51 125 145 110 378 665 579 2522 1753 1198 4076 2007 2491 1857 884 47852 1 Viet Nam Tra Vinh Chau Thanh Dai Thon Mekong River Mainstream 52 69 79 412 906 680 662 535 538 664 955 118353 1 Viet Nam Tra Vinh Tieu Can Khom Dinh Bassac River Mainstream 53 256 291 273 1345 1647 2790 1977 1798 1648 1881 2074 2445 1776 1940 786 1924 1929 2050 2051 1750 531 2585 3390 6208 1419 1400 2014 1881 379454 1 Viet Nam Tra Vinh Tieu Can Khom 3 Khom 3 Bassac River Estuary 54 209 444 295 173 169 215 205 199 360 283 412 174 200 196 215 260 420 181 209 177 194 216 234 204 168 196 223 256 422 246 284 237 446

Table 27 Monthlyestimatesoffishercatchrates(No/day)atthefishercatchmonitoringsites(2003–2010).


VILLAGE NAME 2003 2004 2005 2007 2008 2009 2010

Site AMCF FEVM Country Province District AMCF FEVM River Name Habitat Type Order 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 2 3 4 5 6 7 8 9 10 11 12 1 21 1 Lao PDR Bokeo Houixay Ban Done Mekong River Mainstream 1 0.3 1.9 13.5 8.1 7.1 10.9 22.8 29.7 35.6 16.4 14.6 24.1 20.2 17.5 4.0 4.1 10.9 5.32 1 Lao PDR Luangprabang Ban Hat Ya Ban Hat Gna Ou River Tributary 2 2.0 1.4 1.0 13.0 0.8 1.8 1.5 1.9 2.1 2.3 1.9 1.5 2.5 2.8 4.03 1 1 Lao PDR Luangprabang Luangprabang Ban Pha O Ban Pha O Mekong River Mainstream 3 0.7 1.1 1.1 1.3 1.6 1.2 1.1 1.0 1.4 2.3 0.5 0.7 0.8 0.3 0.7 1.2 0.8 0.9 0.6 0.7 0.9 1.4 1.4 1.5 1.1 1.0 1.3 1.7 1.2 0.74 1 Lao PDR Borikhamxay Paksan Ban Nam Ngieb Ngieb River Tributary 4 2.2 1.5 1.1 0.9 1.2 1.2 1.1 1.4 1.4 1.0 1.0 0.9 1.1 0.8 0.5 0.3 0.2 0.2 0.8 0.5 0.4 1.25 1 1 Lao PDR Borikhamxay Paksan Ban Xinh Xay Ban Sinhxay Mekong River Mainstream 5 1.4 3.6 3.2 3.1 2.7 4.1 4.8 3.7 2.7 3.0 3.2 2.3 2.0 2.4 3.2 6.7 3.1 5.2 9.8 8.9 5.2 3.6 2.8 1.9 2.3 3.3 2.0 1.2 1.0 0.9 1.4 1.2 3.7 1.6 1.9 2.6 2.46 1 Thailand Nongkhai Sri Chiangmai Pa-sak Mekong River Mainstream 6 2.1 1.6 4.1 6.3 6.6 4.4 2.2 1.7 0.97 1 Thailand Nongkhai Sri Chiangmai Huasai Mekong River Mainstream 7 1.7 1.6 1.7 1.7 0.7 1.0 4.2 1.9 1.4 0.9 3.2 1.2 0.78 1 Thailand Loei Chiangkhan Chiangkhan Chiangkhan Mekong River Mainstream 8 1.2 0.1 0.7 2.9 3.4 0.6 1.3 2.2 0.4 2.1 0.7 0.9 0.7 8.2 0.8 4.7 2.1 1.0 1.2 17.8 0.7 1.7 2.4 2.39 1 Thailand Loei Chiangkhan Noy Noy Mekong River Mainstream 9 3.9 2.7 0.5 1.0 0.3 0.6 1.5 0.5 3.6 16.0 4.0 5.4 1.7 0.9 1.1 1.1 1.2 4.1 4.3 33.8 6.2 4.710 1 1 Lao PDR Vientiane Hatxayfong Ban Thamuang Ban Thamuang Mekong River Mainstream 10 0.8 0.7 1.1 0.6 1.2 1.1 1.0 1.0 1.1 1.0 0.5 0.6 0.8 0.5 1.8 4.8 4.1 2.3 1.7 2.5 1.0 1.0 1.6 1.2 1.3 1.2 1.9 1.1 3.911 1 Thailand Nongkhai Tha Bo Donmee Donmee Huai Mong River Tributary 11 0.1 0.6 0.5 2.3 3.7 2.2 41.8 1.4 2.1 7.5 1.7 8.9 136.1 157.0 8.8 2.5 1.5 2.1 4.1 6.1 3.3 6.3 1.312 1 Thailand Nongkhai Tha Bo Thadang Thadang Huai Mong River Tributary 12 1.0 1.0 1.6 1.3 1.2 0.7 2.3 3.3 3.7 3.2 3.5 3.3 3.1 4.6 5.4 6.2 3.2 2.8 4.7 4.2 3.5 3.8 2.513 1 Thailand Nakornpanom Sri Songkhram Tha Bo Tha Bo Songkhram River Floodplain 13 2.9 1.2 6.9 105.7 4.5 0.9 1.8 3.2 3.1 4.1 3.3 5.5 24.4 8.4 3.2 5.2 4.3 11.7 10.2 5.1 5.414 1 Thailand Nakornpanom Tha Utain Chaiyaburi Chaiyaburi Mekong River Mainstream 14 0.7 1.3 2.2 0.7 0.4 0.1 0.1 0.9 1.2 0.8 0.8 0.5 0.2 0.3 0.8 0.9 1.2 1.8 1.6 1.2 1.3 1.6 2.615 1 Lao PDR Khammouane Thakek Ban Mouang Sum Mekong River Mainstream 15 2.1 1.9 4.4 3.0 3.3 5.8 4.4 6.1 4.7 4.1 4.0 3.7 2.8 3.2 4.916 1 Lao PDR Kham Mouan Tha Ngam Tha Ngam Mekong River Floodplain 1617 1 Thailand Sakolnakorn Phon Nakeaw Phaphang Mekong River Floodplain 17 1.1 1.2 1.8 1.1 0.8 0.9 1.2 1.418 1 Thailand Sakolnakorn Wang Yam Nongbeung Mekong River Floodplain 18 1.0 0.5 0.9 1.0 0.9 1.2 2.0 1.219 1 Thailand Nakornphanom Na Keah Pi man thay Mekong River Floodplain 19 3.7 3.3 1.7 1.5 1.0 0.5 1.6 1.8 1.320 1 Thailand Nakornphanom Tad Phanom Ban Nam Kum Mekong River Mainstream 20 2.4 0.9 0.6 1.5 0.7 0.4 1.2 4.5 6.3 1.4 0.7 1.9 5.221 1 Thailand Mukdaharn Wan Yai Song-khon Mekong River Mainstream 21 3.1 3.1 14.2 4.8 2.0 2.0 7.5 14.2 5.4 6.4 2.7 3.3 3.122 1 Thailand Mukdaharn Muang Nalair Mekong River Mainstream 22 5.1 19.1 3.2 3.1 1.9 2.5 4.1 4.9 3.623 1 Thailand Ubon Ratchathani Khemarat Ladcharoen Ladcharoen Mekong River Mainstream 23 2.3 0.7 0.5 1.4 0.7 1.0 1.2 1.4 0.8 1.7 2.4 2.3 1.0 0.7 0.7 1.0 1.0 0.9 0.7 9.2 1.6 1.6 2.1 3.2 3.324 1 1 Cambodia Stung Treng Siem Pang Pres Bang Pres Bang Sekong River Tributary 24 4.5 2.6 1.2 3.3 1.6 0.8 2.0 0.7 0.6 1.0 1.2 1.4 0.9 1.5 1.1 1.2 1.0 0.8 1.2 1.2 2.5 5.5 2.7 3.8 7.1 5.8 7.8 7.9 3.3 5.8 4.3 5.5 7.8 0.9 1.4 1.2 1.1 0.9 2.8 1.3 1.6 1.3 1.3 1.6 1.3 1.9 1.8 1.1 0.8 1.0 1.6 1.0 1.6 1.0 0.7 0.7 0.7 1.2 1.5 1.5 1.3 1.3 1.6 1.125 1 1 Cambodia Ratanakiri Veounsai Banfang Fang Sesan River Tributary 25 4.2 5.8 3.8 2.5 1.4 1.3 1.9 1.2 1.3 1.0 1.3 1.4 1.6 2.6 2.5 0.7 2.0 2.2 2.0 1.2 1.8 1.5 1.9 1.3 1.7 1.9 1.6 4.5 1.4 1.8 3.9 1.7 0.8 1.3 1.2 1.2 1.4 1.2 1.6 1.0 1.1 1.0 1.4 0.9 1.4 0.9 0.7 1.1 1.2 1.7 0.8 1.0 1.2 1.1 0.9 1.1 1.3 0.8 1.1 0.9 1.0 1.1 1.1 1.326 1 1 Cambodia Stung Treng Talarborivat Ou Run Ou Run Mekong River Mainstream 26 13.8 20.4 10.2 7.9 5.4 1.9 1.7 2.2 4.0 2.6 2.1 2.5 6.8 6.8 3.5 2.5 2.5 1.9 3.3 2.4 7.2 3.3 3.9 7.9 9.5 10.9 8.9 5.0 4.3 3.7 2.3 2.9 4.1 2.9 1.9 1.8 1.0 1.7 2.6 2.2 1.1 2.2 3.2 3.7 2.3 2.2 2.1 1.6 2.2 1.5 1.5 2.7 2.4 3.9 3.4 6.4 7.3 8.4 3.0 2.1 1.9 2.0 2.5 2.227 1 Cambodia Stung Treng Stung Treng Kang Memai Mekong River Mainstream 27 3.3 11.8 2.0 0.4 1.0 1.1 1.5 1.9 3.4 1.7 1.8 2.1 3.7 4.7 1.4 0.7 0.8 0.6 0.4 0.5 0.6 1.7 2.0 1.7 1.8 9.1 2.3 1.0 0.7 0.8 0.6 0.3 0.828 1 1 Cambodia Ratanakiri Lum Phat Day Lo Day Lo Srepork River Tributary 28 3.1 1.3 1.4 1.6 1.1 1.7 3.1 4.1 5.3 5.0 4.4 6.7 2.5 4.9 6.7 3.6 1.6 2.1 3.9 13.3 19.1 17.0 12.4 10.9 5.7 3.4 3.6 7.8 3.7 6.2 8.4 7.1 4.5 2.1 3.7 1.0 3.0 6.2 5.5 3.9 2.1 4.4 4.3 2.0 2.5 3.4 5.3 3.6 10.4 6.0 4.8 4.5 5.6 9.8 4.6 2.1 3.5 4.0 2.4 2.3 1.9 5.1 5.5 4.729 1 Cambodia Stung Treng Sesan Sre Sronok Srepork River Tributary 29 3.5 2.4 1.1 0.9 1.6 2.2 4.0 2.5 4.4 2.3 2.5 2.2 2.0 2.1 1.8 1.7 2.2 2.130 1 1 Cambodia Kra Tie Sambo Koh Khne Koh khne Mekong River Mainstream 30 4.1 10.0 16.6 5.0 2.8 4.6 5.7 3.8 3.1 4.0 2.4 4.0 2.4 3.3 2.2 2.7 2.9 2.4 2.7 2.8 3.3 8.0 7.0 4.9 8.5 4.0 9.6 2.2 4.9 3.3 4.3 2.0 2.2 1.8 2.2 2.7 1.7 1.5 1.6 1.4 2.1 1.4 1.8 1.3 1.9 2.3 1.6 2.2 2.5 2.0 2.5 1.5 1.6 1.9 2.0 2.1 2.3 2.1 2.8 2.0 2.6 3.7 2.4 3.131 1 Cambodia Kra Tie Sambo Sandan Mekong River Mainstream 31 9.3 12.6 14.3 20.5 1.3 1.8 1.3 2.4 3.3 3.9 9.8 10.8 8.1 12.0 10.4 3.7 1.4 1.2 2.2 5.7 13.5 12.1 9.7 14.1 11.5 5.4 15.1 10.9 2.7 3.2 2.1 1.9 7.032 1 Cambodia Kampong Cham Kroch Chmar Pram Mekong River Mainstream 32 5.9 13.7 12.6 6.9 17.3 7.1 3.8 3.1 2.9 2.1 3.4 4.6 6.7 10.0 3.6 3.5 2.4 7.5 13.4 12.7 20.6 22.4 13.0 11.0 11.0 13.9 14.9 23.0 8.7 11.0 14.8 12.2 16.433 1 Cambodia Kandal Ponhea Leu Peamchumnik Tonle Sap Floodplain 33 5.2 3.4 1.6 1.3 26.6 1.5 9.8 1.0 1.0 0.9 0.9 0.7 1.0 1.034 1 1 Cambodia Kandal Ponhea Leu Sang Var Sang Var Tonle Sap Tributary 34 6.1 4.6 6.1 3.1 2.7 1.7 2.0 1.9 2.0 1.6 1.7 1.2 1.2 1.0 2.1 0.6 0.7 1.6 0.9 1.9 1.7 2.4 3.9 1.7 1.0 0.8 2.9 2.7 0.5 1.0 1.3 0.6 0.3 0.7 1.5 1.4 0.8 0.8 0.8 0.8 5.5 6.0 2.7 1.4 1.4 1.8 1.6 0.9 1.2 0.7 0.8 1.2 14.9 9.3 1.5 0.9 1.1 1.3 1.4 1.4 0.8 2.1 1.2 18.4 1.435 1 Cambodia Kandal Sa Ang Baren Tonle Sap Floodplain 35 10.4 12.6 7.1 3.9 1.1 2.8 2.9 6.9 3.3 2.1 4.4 7.1 8.4 7.1 4.5 0.8 1.8 4.5 7.0 10.2 10.3 6.5 7.5 6.8 6.8 6.7 5.4 0.6 1.8 4.2 8.0 11.0 8.336 1 Cambodia Kandal Leuk Dek Kbal Chroy Mekong River Floodplain 36 4.4 21.8 21.2 10.8 6.1 5.9 5.5 4.8 3.3 3.0 4.3 4.9 4.9 4.6 3.0 3.0 2.6 2.7 3.2 4.3 4.2 4.2 4.8 6.6 5.7 5.7 3.8 2.2 3.0 3.2 3.7 3.5 4.837 1 Viet Nam An Giang An Phu Phuoc Hung Bassac River Mainstream 37 2.8 8.7 7.6 8.9 14.0 20.0 7.7 9.2 6.5 4.4 4.5 10.2 5.2 7.0 7.3 14.6 23.3 30.1 24.2 8.0 13.7 6.9 8.2 10.8 15.3 23.2 24.8 18.838 1 Viet Nam An Giang An Phu Ap 2 Ap 2 Bassac River Mainstream 38 3.9 4.7 4.5 6.0 6.3 4.6 7.9 4.3 4.9 3.7 4.1 4.2 2.7 2.5 4.8 9.6 5.9 6.0 5.2 4.3 6.3 4.0 2.5 3.0 4.3 4.5 6.1 4.8 5.4 6.0 2.7 6.2 3.839 1 Viet Nam Dong Thap Hong Ngu An Binh A Mekong River Mainstream 39 4.9 8.7 18.7 27.8 43.9 26.0 47.5 16.6 15.4 11.4 11.4 26.4 34.8 52.4 50.1 29.1 62.7 30.6 25.3 26.0 21.0 14.4 15.9 20.6 60.7 48.1 47.5 31.940 1 Viet Nam Dong Thap Tam Nong Phu Duc Mekong River Floodplain 40 21.9 40.9 44.4 45.9 65.2 392.4 248.0 130.5 68.0 41.5 27.1 24.3 42.5 60.4 57.0 94.8 94.4 187.2 194.9 40.1 25.7 27.4 30.8 29.0 64.0 96.8 103.9 182.3 248.9 255.541 1 Viet Nam An Giang Cho Moi My Thuan My Thuan Bassac River Mainstream 41 2.8 2.4 2.3 23.3 24.7 26.0 39.8 7.8 5.7 4.9 4.8 4.4 3.9 4.0 3.6 3.9 5.7 23.7 23.1 5.9 3.9 3.842 1 Viet Nam An Giang Phu Tan Vam Nao Vam Nao Vam Nao canal Tributary 42 3.8 4.3 8.8 18.2 20.7 16.9 5.0 3.7 4.6 5.7 5.7 6.0 1.7 3.7 7.5 5.7 3.7 3.6 4.0 2.9 3.2 2.9 3.0 3.5 9.3 11.1 11.4 5.6 3.3 4.443 1 Viet Nam Dong Thap An Phu Thap Muoi Mekong River Floodplain 43 21.6 38.5 36.7 30.6 38.8 51.4 47.9 30.1 23.1 21.4 20.0 20.9 20.244 1 Viet Nam An Giang Tri Ton An Tuc Mekong River Floodplain 44 3.0 3.0 3.1 7.0 4.9 8.1 4.1 4.3 2.6 2.4 2.4 1.6 1.7 1.3 10.0 9.2 15.9 141.3 59.6 19.6 17.6 10.7 13.1 10.2 10.7 20.2 39.3 71.345 1 Viet Nam Tien Giang Chau Thanh Kim Son Mekong River Mainstream 45 16.4 6.2 1.9 2.6 1.6 2.1 5.9 12.2 6.7 3.8 10.7 4.2 4.346 1 Viet Nam Tien Giang Go Cong Tay Phu Thanh Mekong River Mainstream 46 6.8 10.3 9.8 2.6 0.5 1.1 1.1 1.4 1.4 1.4 1.3 1.7 1.8 1.6 1.3 1.2 1.4 1.8 1.8 1.8 1.7 1.2 1.2 1.3 1.9 2.0 1.8 1.9 1.9 1.9 2.347 1 Viet Nam Vinh Long TX Vinh Long 39/9A Tran Phu Mekong River Mainstream 47 12.1 12.5 16.0 9.0 8.1 6.3 9.2 11.6 14.0 16.9 20.1 13.848 1 1 Viet Nam An Giang Thoai Son Tay Son Tay Son Bassac River Floodplain 48 4.0 3.8 3.7 8.1 8.4 3.7 3.1 2.5 3.1 2.2 2.5 2.4 2.3 2.9 4.5 4.1 7.6 11.2 9.1 6.4 5.3 3.6 3.6 2.9 3.3 3.3 3.5 2.9 8.2 8.4 7.2 6.5 4.1 3.4 3.0 3.3 3.3 3.4 2.9 5.0 9.2 10.6 9.5 6.3 4.2 3.4 4.449 1 Viet Nam Vinh Long Vung Liem Thanh Binh Mekong River Mainstream 49 9.5 11.2 9.8 4.5 3.9 3.6 9.4 12.3 13.3 11.0 10.4 9.8 10.1 13.4 8.3 9.6 11.2 9.3 6.5 6.8 6.3 6.8 8.4 9.1 12.0 8.4 7.8 9.0 7.1 6.9 6.650 1 Viet Nam Vinh Long Vung Liem Lang Lang Mekong River Mainstream 50 2.9 2.1 1.8 2.0 1.9 2.3 3.1 4.0 4.0 5.2 5.1 5.5 3.4 2.2 2.4 2.2 2.0 2.4 3.6 4.0 2.8 3.2 4.6 3.8 2.8 2.3 2.3 2.4 2.4 3.8 3.1 2.4 1.051 1 Viet Nam Vinh Long Tra On Khu 9 Bassac River Mainstream 51 9.0 10.5 7.5 6.3 5.2 4.8 10.4 10.8 9.1 7.5 8.4 9.6 17.9 8.5 5.652 1 Viet Nam Tra Vinh Chau Thanh Dai Thon Mekong River Mainstream 52 2.1 1.8 1.7 2.9 3.0 4.1 2.8 3.2 3.8 4.1 4.153 1 Viet Nam Tra Vinh Tieu Can Khom Dinh Bassac River Mainstream 53 1.0 16.9 10.3 10.4 18.5 5.0 18.7 16.4 27.8 2.6 19.0 4.0 10.8 2.0 3.1 9.4 11.7 7.4 10.3 28.3 13.8 10.3 53.2 3.7 6.0 14.1 7.954 1 Viet Nam Tra Vinh Tieu Can Khom 3 Khom 3 Bassac River Estuary 54 7.4 10.5 11.2 10.9 10.6 10.8 14.3 11.0 11.7 8.2 17.5 6.4 7.7 7.1 7.6 9.1 18.9 7.5 9.1 7.7 7.7 8.9 12.6 9.8 6.8 9.5 9.2 10.3 11.7 9.4 10.4 9.0 8.6

Table 28 Monthlyestimatesoffishercatchrates(kg/day)atthefishercatchmonitoringsites(2003–2010).

Annex

Table 29 Pearson coefficients for correlations between average daily catch rates (kg/day) by month at fisher catch monitoring locations.

Correlationsa

1 .400* .154 -.092 .093 -.054 -.072 .387* -.148 -.120. .035 .415 .630 .624 .778 .709 .035 .435 .586

30 28 30 30 30 30 29 30 30 23.400* 1 .595** -.087 .509** -.116 -.033 .088 -.091 -.084.035 . .001 .654 .005 .548 .865 .652 .639 .696

28 29 29 29 29 29 29 29 29 24.154 .595** 1 -.105 .581** .445** .136 .169 .049 -.092.415 .001 . .530 .000 .000 .293 .187 .704 .549

30 29 63 38 63 63 62 63 63 45-.092 -.087 -.105 1 -.076 -.067 -.102 .116 -.057 -.057.630 .654 .530 . .649 .687 .546 .486 .735 .785

30 29 38 38 38 38 37 38 38 25.093 .509** .581** -.076 1 .459** -.092 .296* -.021 -.045.624 .005 .000 .649 . .000 .471 .017 .870 .771

30 29 63 38 64 64 63 64 63 45-.054 -.116 .445** -.067 .459** 1 .063 .035 -.070 -.061.778 .548 .000 .687 .000 . .624 .783 .586 .690

30 29 63 38 64 64 63 64 63 45-.072 -.033 .136 -.102 -.092 .063 1 -.087 .065 -.075.709 .865 .293 .546 .471 .624 . .497 .615 .622

29 29 62 37 63 63 63 63 62 45.387* .088 .169 .116 .296* .035 -.087 1 -.038 -.045.035 .652 .187 .486 .017 .783 .497 . .769 .768

30 29 63 38 64 64 63 64 63 45-.148 -.091 .049 -.057 -.021 -.070 .065 -.038 1 -.052.435 .639 .704 .735 .870 .586 .615 .769 . .729

30 29 63 38 63 63 62 63 64 46-.120 -.084 -.092 -.057 -.045 -.061 -.075 -.045 -.052 1.586 .696 .549 .785 .771 .690 .622 .768 .729 .

23 24 45 25 45 45 45 45 46 46

Pearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)NPearson CorrelationSig. (2-tailed)N

Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan

Thamuang BANFANG Ban Xinh Xay Day Lo Koh Khne Ou Run Pres Bang Sang Var Tay Son

Correlat ion is signif icant at the 0.05 level (2-tailed).*.

Correlat ion is signif icant at the 0.01 level (2-tailed).**.

SPECIES = Cirrhinus lobatusa.

Correlationsb

1 .a -.065 -.067 -.038 -.056 -.062 .102 -.048 .a

. . .733 .723 .842 .770 .749 .593 .802 .30 28 30 30 30 30 29 30 30 23

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .28 29 29 29 29 29 29 29 29 24

-.065 .a 1 -.065 .121 -.067 .280* -.058 -.045 .a

.733 . . .700 .347 .604 .027 .650 .726 .30 29 63 38 63 63 62 63 63 45

-.067 .a -.065 1 .686** .694** -.072 -.085 .837** .a

.723 . .700 . .000 .000 .673 .613 .000 .30 29 38 38 38 38 37 38 38 25

-.038 .a .121 .686** 1 .647** -.004 -.076 .213 .a

.842 . .347 .000 . .000 .974 .551 .093 .30 29 63 38 64 64 63 64 63 45

-.056 .a -.067 .694** .647** 1 -.110 -.090 .708** .a

.770 . .604 .000 .000 . .391 .481 .000 .30 29 63 38 64 64 63 64 63 45

-.062 .a .280* -.072 -.004 -.110 1 -.040 -.080 .a

.749 . .027 .673 .974 .391 . .758 .538 .29 29 62 37 63 63 63 63 62 45

.102 .a -.058 -.085 -.076 -.090 -.040 1 -.043 .a

.593 . .650 .613 .551 .481 .758 . .736 .30 29 63 38 64 64 63 64 63 45

-.048 .a -.045 .837** .213 .708** -.080 -.043 1 .a

.802 . .726 .000 .093 .000 .538 .736 . .30 29 63 38 63 63 62 63 63 45

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .23 24 45 25 45 45 45 45 45 45


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan




Cannot be computed because at least one of the v ariables is constant.a.

SPECIES = Cirrhinus microlepisb.

Cirrhinus lobatus

Cirrhinus microlepis

Annex


Page 126

Correlationsb

1 -.161 .063 .571** -.122 -.069 -.158 .176 .018 .a

. .412 .740 .001 .522 .717 .412 .352 .924 .30 28 30 30 30 30 29 30 30 23

-.161 1 -.164 .318 -.368* -.190 -.402* .113 .062 .a

.412 . .396 .093 .050 .323 .031 .559 .750 .28 29 29 29 29 29 29 29 29 24

.063 -.164 1 -.153 .132 .585** .265* -.039 .023 .a

.740 .396 . .360 .308 .000 .039 .765 .861 .30 29 62 38 62 62 61 62 62 45

.571** .318 -.153 1 -.227 -.388* -.111 .147 -.073 .a

.001 .093 .360 . .170 .016 .514 .379 .661 .30 29 38 38 38 38 37 38 38 25

-.122 -.368* .132 -.227 1 .609** -.041 -.024 -.135 .a

.522 .050 .308 .170 . .000 .752 .852 .295 .30 29 62 38 63 63 62 63 62 45

-.069 -.190 .585** -.388* .609** 1 .123 -.093 -.009 .a

.717 .323 .000 .016 .000 . .341 .466 .942 .30 29 62 38 63 63 62 63 62 45

-.158 -.402* .265* -.111 -.041 .123 1 -.146 .235 .a

.412 .031 .039 .514 .752 .341 . .258 .068 .29 29 61 37 62 62 62 62 61 45

.176 .113 -.039 .147 -.024 -.093 -.146 1 -.104 .a

.352 .559 .765 .379 .852 .466 .258 . .421 .30 29 62 38 63 63 62 63 62 45

.018 .062 .023 -.073 -.135 -.009 .235 -.104 1 .a

.924 .750 .861 .661 .295 .942 .068 .421 . .30 29 62 38 62 62 61 62 62 45

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .23 24 45 25 45 45 45 45 45 45


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan





SPECIES = Cosmochilus harmandib.

Correlationsb

1 .038 .a .009 .a .a .a .a .a .a

. .847 . .963 . . . . . .30 28 30 30 30 30 29 30 30 23

.038 1 .a .575** .a .a .a .a .a .a

.847 . . .001 . . . . . .28 29 29 29 29 29 29 29 29 24

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .30 29 63 38 63 63 62 63 63 45

.009 .575** .a 1 .a .a .a .a .a .a

.963 .001 . . . . . . . .30 29 38 38 38 38 37 38 38 25

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .30 29 63 38 64 64 63 64 63 45

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .30 29 63 38 64 64 63 64 63 45

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .29 29 62 37 63 63 63 63 62 45

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .30 29 63 38 64 64 63 64 63 45

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .30 29 63 38 63 63 62 63 63 45

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .23 24 45 25 45 45 45 45 45 45


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan




SPECIES = Hemibagrus nemurusb.

Cosmochilus harmandi

Hemibagrus nemurus


Labeo chrysophekadion

Correlationsa

1 .436* .088 .248 .264 .166 -.165 .309 -.002 -.309. .020 .642 .186 .158 .382 .392 .097 .990 .152

30 28 30 30 30 30 29 30 30 23.436* 1 .126 .029 .200 .035 .481** -.030 -.057 .283.020 . .515 .881 .297 .858 .008 .879 .767 .180

28 29 29 29 29 29 29 29 29 24.088 .126 1 .148 .169 .537** .522** .621** .120 -.084.642 .515 . .374 .186 .000 .000 .000 .347 .584

30 29 63 38 63 63 62 63 63 45.248 .029 .148 1 .392* .078 -.047 .038 -.090 -.120.186 .881 .374 . .015 .643 .782 .821 .592 .569

30 29 38 38 38 38 37 38 38 25.264 .200 .169 .392* 1 .674** .398** -.028 .596** -.135.158 .297 .186 .015 . .000 .001 .827 .000 .378

30 29 63 38 64 64 63 64 63 45.166 .035 .537** .078 .674** 1 .553** .139 .605** -.055.382 .858 .000 .643 .000 . .000 .273 .000 .720

30 29 63 38 64 64 63 64 63 45-.165 .481** .522** -.047 .398** .553** 1 .517** .321* -.097.392 .008 .000 .782 .001 .000 . .000 .011 .524

29 29 62 37 63 63 63 63 62 45.309 -.030 .621** .038 -.028 .139 .517** 1 .037 -.247.097 .879 .000 .821 .827 .273 .000 . .776 .102

30 29 63 38 64 64 63 64 63 45-.002 -.057 .120 -.090 .596** .605** .321* .037 1 -.125.990 .767 .347 .592 .000 .000 .011 .776 . .410

30 29 63 38 63 63 62 63 64 46-.309 .283 -.084 -.120 -.135 -.055 -.097 -.247 -.125 1.152 .180 .584 .569 .378 .720 .524 .102 .410 .

23 24 45 25 45 45 45 45 46 47


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan




SPECIES = Henicorhy nchus siamensisa.

Correlationsa

1 .128 .155 -.295 -.248 -.185 -.098 -.185 -.096 -.141. .515 .414 .114 .186 .326 .614 .328 .614 .522

30 28 30 30 30 30 29 30 30 23.128 1 .058 .177 -.197 -.120 -.046 -.082 .015 .089.515 . .763 .359 .306 .537 .813 .674 .940 .678

28 29 29 29 29 29 29 29 29 24.155 .058 1 -.148 .258* -.020 .174 -.003 -.015 -.041.414 .763 . .376 .041 .875 .177 .979 .905 .789

30 29 63 38 63 63 62 63 63 45-.295 .177 -.148 1 .361* .581** .470** .161 .223 -.136.114 .359 .376 . .026 .000 .003 .333 .178 .518

30 29 38 38 38 38 37 38 38 25-.248 -.197 .258* .361* 1 .519** .383** -.012 .014 -.235.186 .306 .041 .026 . .000 .002 .926 .916 .120

30 29 63 38 64 64 63 64 63 45-.185 -.120 -.020 .581** .519** 1 .247 .054 .015 -.159.326 .537 .875 .000 .000 . .051 .670 .908 .297

30 29 63 38 64 64 63 64 63 45-.098 -.046 .174 .470** .383** .247 1 -.041 .118 -.132.614 .813 .177 .003 .002 .051 . .751 .360 .389

29 29 62 37 63 63 63 63 62 45-.185 -.082 -.003 .161 -.012 .054 -.041 1 -.182 -.183.328 .674 .979 .333 .926 .670 .751 . .154 .230

30 29 63 38 64 64 63 64 63 45-.096 .015 -.015 .223 .014 .015 .118 -.182 1 -.249.614 .940 .905 .178 .916 .908 .360 .154 . .095

30 29 63 38 63 63 62 63 64 46-.141 .089 -.041 -.136 -.235 -.159 -.132 -.183 -.249 1.522 .678 .789 .518 .120 .297 .389 .230 .095 .

23 24 45 25 45 45 45 45 46 47


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan




SPECIES = Labeo chry sophekadiona.

Annex


Page 128


Pangasius larnaudii

Correlationsb

1 .026 .a .006 -.093 -.190 -.131 .290 -.076 .a

. .894 . .976 .626 .316 .498 .120 .689 .30 28 30 30 30 30 29 30 30 23

.026 1 .a .138 .123 .092 -.114 -.012 .181 .060

.894 . . .474 .525 .636 .555 .949 .348 .78028 29 29 29 29 29 29 29 29 24

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .30 29 63 38 63 63 62 63 63 45

.006 .138 .a 1 -.271 .133 .480** .020 .117 -.175

.976 .474 . . .100 .426 .003 .907 .483 .40230 29 38 38 38 38 37 38 38 25

-.093 .123 .a -.271 1 -.107 -.072 .020 .093 -.079.626 .525 . .100 . .400 .576 .876 .469 .604

30 29 63 38 64 64 63 64 63 45-.190 .092 .a .133 -.107 1 .020 -.130 -.150 -.072.316 .636 . .426 .400 . .877 .305 .241 .640

30 29 63 38 64 64 63 64 63 45-.131 -.114 .a .480** -.072 .020 1 -.198 -.079 .249.498 .555 . .003 .576 .877 . .120 .543 .098

29 29 62 37 63 63 63 63 62 45.290 -.012 .a .020 .020 -.130 -.198 1 .157 -.061.120 .949 . .907 .876 .305 .120 . .220 .691

30 29 63 38 64 64 63 64 63 45-.076 .181 .a .117 .093 -.150 -.079 .157 1 -.019.689 .348 . .483 .469 .241 .543 .220 . .899

30 29 63 38 63 63 62 63 64 46.a .060 .a -.175 -.079 -.072 .249 -.061 -.019 1. .780 . .402 .604 .640 .098 .691 .899 .

23 24 45 25 45 45 45 45 46 47


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan




SPECIES = Pangasius conchophilusb.

Correlationsb

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .30 28 30 30 30 30 29 30 30 23

.a 1 -.103 -.036 -.033 -.079 -.122 -.063 -.062 -.050

. . .595 .854 .867 .682 .530 .747 .748 .81828 29 29 29 29 29 29 29 29 24

.a -.103 1 -.095 -.066 -.098 -.160 .013 -.009 .211

. .595 . .570 .605 .444 .216 .921 .943 .16430 29 63 38 63 63 62 63 63 45

.a -.036 -.095 1 -.067 -.066 -.081 -.047 -.053 -.047

. .854 .570 . .690 .696 .632 .779 .753 .82230 29 38 38 38 38 37 38 38 25

.a -.033 -.066 -.067 1 -.102 .007 -.058 -.087 .054

. .867 .605 .690 . .422 .958 .649 .498 .72530 29 63 38 64 64 63 64 63 45

.a -.079 -.098 -.066 -.102 1 .016 -.113 -.046 .153

. .682 .444 .696 .422 . .902 .372 .722 .31630 29 63 38 64 64 63 64 63 45

.a -.122 -.160 -.081 .007 .016 1 -.100 -.132 -.015

. .530 .216 .632 .958 .902 . .437 .306 .92429 29 62 37 63 63 63 63 62 45

.a -.063 .013 -.047 -.058 -.113 -.100 1 -.112 -.042

. .747 .921 .779 .649 .372 .437 . .384 .78630 29 63 38 64 64 63 64 63 45

.a -.062 -.009 -.053 -.087 -.046 -.132 -.112 1 -.045

. .748 .943 .753 .498 .722 .306 .384 . .76530 29 63 38 63 63 62 63 64 46

.a -.050 .211 -.047 .054 .153 -.015 -.042 -.045 1

. .818 .164 .822 .725 .316 .924 .786 .765 .23 24 45 25 45 45 45 45 46 47


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan



SPECIES = Pangasius larnaudiib.

Correlationsb

1 .a .092 -.080 -.024 .264 -.069 -.049 -.167 -.064. . .628 .675 .899 .158 .721 .799 .378 .770

30 28 30 30 30 30 29 30 30 23.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .28 29 29 29 29 29 29 29 29 24

.092 .a 1 -.175 .128 -.159 -.103 .046 -.180 -.083

.628 . . .295 .318 .213 .425 .721 .159 .58830 29 63 38 63 63 62 63 63 45

-.080 .a -.175 1 -.116 .152 .112 -.065 -.141 -.075.675 . .295 . .490 .363 .508 .700 .400 .721

30 29 38 38 38 38 37 38 38 25-.024 .a .128 -.116 1 -.018 .056 -.073 -.095 .192.899 . .318 .490 . .887 .665 .567 .458 .206

30 29 63 38 64 64 63 64 63 45.264 .a -.159 .152 -.018 1 -.026 -.038 -.034 -.068.158 . .213 .363 .887 . .837 .765 .789 .656

30 29 63 38 64 64 63 64 63 45-.069 .a -.103 .112 .056 -.026 1 -.005 .012 .009.721 . .425 .508 .665 .837 . .972 .925 .952

29 29 62 37 63 63 63 63 62 45-.049 .a .046 -.065 -.073 -.038 -.005 1 -.068 -.031.799 . .721 .700 .567 .765 .972 . .595 .840

30 29 63 38 64 64 63 64 63 45-.167 .a -.180 -.141 -.095 -.034 .012 -.068 1 -.057.378 . .159 .400 .458 .789 .925 .595 . .706

30 29 63 38 63 63 62 63 64 46-.064 .a -.083 -.075 .192 -.068 .009 -.031 -.057 1.770 . .588 .721 .206 .656 .952 .840 .706 .

23 24 45 25 45 45 45 45 46 47


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan



SPECIES = Pangasius pleurotaeniab.

Correlationsb

1 .815** .062 .284 -.256 -.133 .410* -.044 -.038 .a

. .000 .744 .129 .172 .482 .027 .816 .841 .30 28 30 30 30 30 29 30 30 23

.815** 1 .047 .309 -.386* .005 .326 -.078 .029 .a

.000 . .809 .103 .039 .978 .084 .689 .881 .28 29 29 29 29 29 29 29 29 24

.062 .047 1 .303 .296* .055 -.015 .200 -.086 .a

.744 .809 . .064 .018 .669 .908 .116 .501 .30 29 63 38 63 63 62 63 63 45

.284 .309 .303 1 .310 -.122 -.086 .336* -.118 .a

.129 .103 .064 . .058 .467 .611 .039 .480 .30 29 38 38 38 38 37 38 38 25

-.256 -.386* .296* .310 1 .177 .086 .101 -.157 .a

.172 .039 .018 .058 . .161 .502 .427 .218 .30 29 63 38 64 64 63 64 63 45

-.133 .005 .055 -.122 .177 1 .379** .070 -.093 .a

.482 .978 .669 .467 .161 . .002 .585 .470 .30 29 63 38 64 64 63 64 63 45

.410* .326 -.015 -.086 .086 .379** 1 -.090 -.130 .a

.027 .084 .908 .611 .502 .002 . .482 .315 .29 29 62 37 63 63 63 63 62 45

-.044 -.078 .200 .336* .101 .070 -.090 1 -.037 .a

.816 .689 .116 .039 .427 .585 .482 . .772 .30 29 63 38 64 64 63 64 63 45

-.038 .029 -.086 -.118 -.157 -.093 -.130 -.037 1 .a

.841 .881 .501 .480 .218 .470 .315 .772 . .30 29 63 38 63 63 62 63 64 46

.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .23 24 45 25 45 45 45 45 46 47


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan





SPECIES = Poropuntius malcolmib.


Poropuntius malcolmi

Annex


Page 130

Puntioplites proctozystron


Correlationsb

1 .a -.118 -.076 .118 -.150 -.056 -.036 -.081 .548**. . .534 .692 .535 .430 .773 .849 .669 .007

30 28 30 30 30 30 29 30 30 23.a .a .a .a .a .a .a .a .a .a

. . . . . . . . . .28 29 29 29 29 29 29 29 29 24

-.118 .a 1 -.091 -.045 .268* .272* -.095 -.057 -.298*.534 . . .586 .724 .034 .032 .457 .659 .047

30 29 63 38 63 63 62 63 63 45-.076 .a -.091 1 -.048 -.149 .020 -.167 -.078 -.033.692 . .586 . .775 .373 .906 .316 .643 .875

30 29 38 38 38 38 37 38 38 25.118 .a -.045 -.048 1 .018 .443** .104 -.054 -.133.535 . .724 .775 . .886 .000 .414 .675 .383

30 29 63 38 64 64 63 64 63 45-.150 .a .268* -.149 .018 1 .320* -.142 -.025 -.219.430 . .034 .373 .886 . .011 .264 .848 .149

30 29 63 38 64 64 63 64 63 45-.056 .a .272* .020 .443** .320* 1 -.004 -.116 -.309*.773 . .032 .906 .000 .011 . .977 .371 .039

29 29 62 37 63 63 63 63 62 45-.036 .a -.095 -.167 .104 -.142 -.004 1 -.057 -.284.849 . .457 .316 .414 .264 .977 . .656 .058

30 29 63 38 64 64 63 64 63 45-.081 .a -.057 -.078 -.054 -.025 -.116 -.057 1 -.053.669 . .659 .643 .675 .848 .371 .656 . .725

30 29 63 38 63 63 62 63 64 46.548** .a -.298* -.033 -.133 -.219 -.309* -.284 -.053 1.007 . .047 .875 .383 .149 .039 .058 .725 .

23 24 45 25 45 45 45 45 46 47


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan





SPECIES = Puntioplites proctozystronb.

Correlationsb

1 -.118 -.061 .006 .240 .524** .a -.119 -.238 .623**. .549 .749 .974 .202 .003 . .532 .204 .002

30 28 30 30 30 30 29 30 30 23-.118 1 -.026 .180 -.098 .158 .a -.150 .177 -.089.549 . .894 .350 .613 .414 . .438 .357 .680

28 29 29 29 29 29 29 29 29 24-.061 -.026 1 -.006 .462** .043 -.062 -.120 -.028 -.049.749 .894 . .971 .000 .739 .630 .350 .828 .748

30 29 63 38 63 63 62 63 63 45.006 .180 -.006 1 -.074 -.046 -.028 -.081 .042 -.073.974 .350 .971 . .658 .784 .870 .631 .804 .731

30 29 38 38 38 38 37 38 38 25.240 -.098 .462** -.074 1 .254* .044 -.039 -.071 .174.202 .613 .000 .658 . .043 .734 .759 .582 .254

30 29 63 38 64 64 63 64 63 45.524** .158 .043 -.046 .254* 1 -.071 .138 -.115 .163.003 .414 .739 .784 .043 . .580 .275 .371 .286

30 29 63 38 64 64 63 64 63 45.a .a -.062 -.028 .044 -.071 1 -.079 -.034 .158. . .630 .870 .734 .580 . .538 .792 .300

29 29 62 37 63 63 63 63 62 45-.119 -.150 -.120 -.081 -.039 .138 -.079 1 -.031 -.070.532 .438 .350 .631 .759 .275 .538 . .812 .647

30 29 63 38 64 64 63 64 63 45-.238 .177 -.028 .042 -.071 -.115 -.034 -.031 1 -.085.204 .357 .828 .804 .582 .371 .792 .812 . .573

30 29 63 38 63 63 62 63 64 46.623** -.089 -.049 -.073 .174 .163 .158 -.070 -.085 1.002 .680 .748 .731 .254 .286 .300 .647 .573 .

23 24 45 25 45 45 45 45 46 47


Ban Pha O

Ban Thamuang

BANFANG

Ban Xinh Xay

Day Lo

Koh Khne

Ou Run

Pres Bang

Sang Var

Tay Son

Ban Pha OBan





SPECIES = Yasuhikotakia modestab.


P.O. Box 623, Phnom Penh, CambodiaTel. (855-23) 425 353 Fax. (855-23) 425 363

Office of the Secretariat in Vientiane (OSV) Office of the Chief Executive Officer 184 Fa Ngoum Road, P.O. Box 6101,

Vientiane, Lao PDRTel. (856-21) 263 263 Fax. (856-21) 263 264

© Mekong River CommissionE-mail: [email protected]: www.mrcmekong.org

E-mail: [email protected] Website: www.mrcmekong.org


P.O. Box 623, Phnom Penh, Cambodia

Tel. (855-23) 425 353 Fax. (855-23) 425 363

Office of the Secretariat in Vientiane (OSV), Office of the Chief Executive Officer

184 Fa Ngoum Road, P.O. Box 6101, Vientiane, Lao PDR

Tel. (856-21) 263 263 Fax. (856-21) 263 264

integrated analysis of data from mrc fisheries monitoring ...€¦ · the lao lee trap fishery...

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