differences in condition factors and life history traits

กลมงานวจยและพฒนาการบรหารจดการทรพยากรประมงน าจด

Pisit Phomikong

Differences in condition factors and life history

traits of 4 cyprinids among the dammed and

un-dammed Mekong’s tributaries in Thailand

by

Fisheries Program, Faculty of Agriculture Ubon Ratchathani University Ubon

Ratchathani

19th July 2011


The Mekong fish

The Mekong River ranks the third in freshwater fishspecies richness among rivers in the world, with 783species identified and expected around 1200 species.

The most of fish species are characterized as extensivemigrants, often migrating over hundreds of kilometersand 87 % of well known species are migratory.

This basin is also renowned as having one of the mostproductive inland fisheries in the world, producing 2.6million tones of fish a year (Van Zalinge et al. 2004).


The Mekong river is experiencing an increasing demand for dam construction in its mainstream and tributaries for hydro-electricity generation and for higher agricultural production and irrigation.

Problem Statements

Moreover, alterations to flow and flood regimes due to

damming would limit fish production and reduce fish

abundance both qualitative and quantitative.


Note :

as in 2000

planned to

be constructed

Fig. 1 Map of the Dams on the Mekong tributaries (Kite 2000)


The study was base on

• The differences condition factors and life history

traits of four species following this, O. hasselti,

B. gonionotus, H. siamensis and P. protozysron among

have the dammed and un-dammed in the Mekong’s

tributaries in Thailand .

The objectives

Henicorhynchus siamensisOsteochilus hasselti Babonymus gonionotus Puntioplites proctozyron


Sampling sites located in three tributaries of the

Mekong River located in northeastern Thailand.

• Mun River: Characterized by having a large

hydropower dam.

• Gam River: the series of low-head irrigation

dams and connected to the large swamp (Nong Harn).

• Songkram River: The River is largely intact, and

have no dams.

Sampling areas


Nam Songkram River (intact tributary)

5 sampling stations

Nam Gam River (cascaded tributary with 5 low-head dams)

6 sampling stations

Nam Mun River (blockage by the large “run-of the river“ hydropower dam at 6 km to the river mouth) 5 sampling stations

Fig. 2 Sampling sites located in three tributaries of the Mekong River Thailand.


Fig. 3 Map of 5 sampling stations at Nam Mun

.

.

Mun River Ubon Ratchathani

อ.วารนช าราบ อ.พบลมงสาหาร

อ.โขงเจยม

เขอนสรนธร

แกงตะนะ

แกงสะพอ Pak Mun Dam

N

0 5 10 กม.

4

5

32

1

Mekong River

Warin Chamrap LOA PDR.


Fig. 4 Map of 6 sampling stations at Nam Gam

Nong Harn swamp

Gam River

0 5 10 กม.

1

23

4

5

6

Mekong Rivernakhonphanom

sakonnakhon

Upper Num Gam Dam

Lower Num Gam Dam

Na Khu (Upper Dam)

Na Kam (Upper Dam)

Muang Kham (Upper Dam)

Na Tong Watthana

(Upper Dam)

N


Fig. 5 Map of 5 sampling stations at Songkram River

5

43

21

0 5 10 กม.

Mekong River

Songkram River

nakhonphanom

sakonnakhon


Mekong River


Period of study: at two month intervals from August 2009 to June 2010 at sites in each of the three tributaries.

Fish samples: Fish will be sampled at the sampling stations with non-selective using electro-fishing and small mesh beach seine

Samples will be counted, measured (total length to 1 mm) and weighed (to 0.1 g ).

Field Procedures


Fig. 6 Working in the field


Data collection and analysis

The relative condition factor (Kn) was calculated as below.

Where: are the actual weight and estimated weight

(in gram) of individual fish.

• And was estimated based on the length-weight regression

and was calculated as below.

Data analysis

w w

wwKn

balw


The proportion of mature females (stages 5 and 6) to

immature fish (Pi) at each length class (Li at 1 cm TL)

were then determined the size at 50% maturity (L50)

was calculated as below.

Data analysis

: where S1 and S2 are the equation coefficients

iLSSie

P211

1


• Asymptotic length (L): of estimated by the length of

largest individual in the samples and was calculated as

below. (Froese and Biholan 2000)

• Growth parameter (K): Length frequency distribution

were made for estimating the curvature (K) of the Von

Bertalanffy growth function.

• Employing by the “K-scan” in the FiSAT II program.

Data Analysis

maxlog9841.0044.0log LL


• Phi prime (ø’): Using by estimated L as an input

parameters K.

• Reliability of K was tested by the Munro’s phi prime

(Munro and Pauly, 1983).

• Which is similar the estimated ø’ values were tested with

the values taken from FishBase (Froese and Pauly 2010).

Data Analysis

LK log2log'


Data collection and analysis

Principle component analysis (PCA) :

• was employed to summarize the variations of life history

traits and their relationships to the surveys.

• In which input matrix data was formed by 18 surveys and

4 variables, i.e. Kn, GSI, % of mature and no. of larvae.

• All statistical analyses was performed by using the Program R (R Development Core Team 2011)

Data Analysis


Results

The differences in condition factors

• The total of 1,744 fishes from four species, was collected in

the study.

• The weight increased proportionally with length and was

confirmed as that the exponential values (b) of the length-

weight regression were around 3.

• The conformity of all fish species to the isometric.


The relative condition factor (Kn) :

Indicates whether an individual is in better (Kn > 1) or

worse (Kn < 1) condition than an average individual with

the same length (Knaepkens et al. 2002).

• Moreover, there was no significant deviations from

expected value (i.e. Kn =1, 2 -test, P-value > 0.05) in all estimated Kn.

Results


Fig. 7 the relative condition factors (Kn) were observed in all species .Kn is in better (Kn > 1) or worse (Kn < 1) (Knaepkens et al. 2002).


The matured females

• were generally in a high proportion and spent females

(stage 6 ovaries) were common in June.

• In which only spent O. hasselti females could prolong

the spent period between June to October.

• Two peaks of GSI were commonly observed in the

Songkram River for all four species

• The single peaks were found in the remaining two rivers.

• Except for O. hasselti , the remaining three species showed the delay of increasing in GSI in Nam Gam River .

Results


Fig. 8 The changes in reproductive aspects were indicated by changes

of ovaries and stages of development and GSI.


Fig. 9 The changes in reproductive aspects were indicated by changes

of ovaries and stages of development and GSI.


Life history traits

Proportion of mature females indicated:

• That lengths at 50% maturity (L50) of all selected species

in the intensively regulated river (i.e., Gam River). Were

relatively larger than those fishes in the intact river (i.e.,

Songkram River).

• Except for P. proctozysron, the largest asymptotic lengths

(L) of the three remaining species were observed in the Gam River.

Results


• The curvature parameter (K), which used to determine

how fast the fish approaches its L

• The highest values of the three species viz., O. hasselti,

H. siamensis and P. protozysron were obtained from

the Songkram River.

• Meanwhile all estimated L and K were reliable since

none of the estimated phi prime did deviate from the ø’,

which were taken from FishBase. (Table 2)

Results


Table 1

1 Oh_NG 16.18 29.18 0.27 2.36(3.21)

2 Oh_SK 14.74 21.52 0.60 2.44

3 Oh_NM 17.05 22.04 0.39 2.28

4 Bg_NG 17.53 37.32 0.19 2.42(2.71)

5 Bg_SK 15.92 36.91 0.11 2.18

6 Bg_NM 17.93 33.72 0.15 2.23

7 Hs_NG 17.3 35.47 0.19 2.37(3.15)

8 Hs_SK 17.07 22.35 1.40 2.84

9 Hs_NM 14.89 21.10 0.63 2.45

10 Pp_NG 19.32 27.22 0.31 2.36(2.16)

11 Pp_SK 17.37 30.63 0.42 2.60

12 Pp_NM 14.62 24.01 0.26 2.18

L50 L∞ KNo Sp_Station Ø

Table 1 Results were Life history traits of samples for individual

species among the three rivers.


The result of PCA :

was presented in the two axes, Axis F1 was explained 37 %

of total variance and Axis F2 at 14 %.

• In which the temporal in GSI and proportion of matured

females were along the negative side of Axis F1.

• The obviously found concurring to the onset of the rainy

season (i.e. June). The abundance of the larvae of all species

was positive.

Results


Fig. 10 The result of PCA was presented in the two axes.


•Axis F2. The larvae of O. hasselti and P. proctozysron were

along the opposite side of Axis F1 and positive to Axis F2

• which followed the late of rainy season (August to

October), meanwhile the other two species were also show

the positively trend in Songkram River during June.

• The short arms of Kn and closed to the centre of the

PCA implied that there was not much temporal variation

of this indicator for all species in these three rivers.

Results


Fig. 10 The result of PCA was presented in the two axes.


Conclusion

• The fluctuations in the relative condition factors (Kn)

were observed in all species, there was no consistency in

temporal variation of on the individual species, among the

three rivers.

• Delay in maturity and slow growth

• The selected species were observed in nam Gam and this

can compared to the resultr

•Riverine Siamese mud carp (Henicorhynchus siamensis) in the

man-made lake compared to the river inhabitants

(Suvarnaraksha et al. 2011).


Ubon Ratchathani University

Inland Fisheries Research and Development Institute

National Institute for Environmental Studies


ALIGATOR GOZAIRIMASU

Thank you


a b

1 Oh_NG 14.26±3.82a

0.0000079 3.12

2 Oh_SK 12.79±3.41b

0.0000355 2.82

3 Oh_NM 12.61±3.23b

0.0000084 3.11

4 Bg_NG 10.39±7.37a

0.0000111 3.05

5 Bg_SK 14.49±6.65ab

0.0000027 3.33

6 Bg_NM 12.84±4.21b

0.0000097 3.08

7 Hs_NG 11.21±4.33a

0.0000249 2.83

8 Hs_SK 12.93±3.65b

0.0000087 3.05

9 Hs_NM 10.43±3.89c

0.0000235 2.85

10 Pp_NG 13.69±4.81a

0.0000023 3.35

11 Pp_SK 13.65±3.68a

0.0000057 3.17

12 Pp_NM 8.34±3.43b

0.0000992 2.56

No Sp_Station Aver Leng±SdCoefficient Length-weight relationship

Table 1 There were statistical differences in the average length

of samples for individual species among the three rivers.

differences in condition factors and life history traits

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