issn: 2347-5129 dominant small pelagic in hinatuan passage caraga … · caraga region, philippines...

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International Journal of Fisheries and Aquatic Studies 2016; 4(4): 286-303

ISSN: 2347-5129

(ICV-Poland) Impact Value: 5.62 (GIF) Impact Factor: 0.352 IJFAS 2016; 4(4): 286-303 © 2016 IJFAS

www.fisheriesjournal.com Received: 06-05-2016 Accepted: 07-06-2016

Joyce M Baclayo

Bureau of Fisheries and Aquatic

Resources- Caraga Region

Peṅaranda St., Surigao City, Philippines

Romeo C Deligero




Laila M Holoyohoy




Eunice C Bognot

National Fisheries Research and

Development Institute (NFRDI)

101 Mother Ignacia Ave.,

Quezon City, Philippines

Correspondence

Joyce M Baclayo




Status of dominant small pelagic in Hinatuan passage

Caraga region, Philippines

Joyce M Baclayo, Romeo C Deligero, Laila M Holoyohoy and Eunice C

Bognot

Abstract Rastrelliger kanagurta, Selar crumenophthalmus, Decapterus russelli and Amblygaster sirm were the

dominant small pelagic fishes in Hinatuan Passage contributing 32% of the total production in the area.

This paper presents the status of these four dominant small pelagic fishes as to their abundance,

seasonality, length frequency distribution and population parameters relevant to the management and

sustainability of the fishery resources in the area.

Results show that commercial Danish seines, Ring nets, Bagnets and municipal multiple hook and lines

and Drift gillnets, were the main gears exploiting these four small pelagic fishes. It was shown further in

the analysis of fish samples that these gears caught an average of 77% immature fish which did not even

reach its length at first maturity, though the growth rate (K) and length infinity (Loo) vary by species.

The present level of exploitation rates ranged from 0.4-0.84 which is an indication of biological

overfishing.

Keywords: Small pelagic species (Rastrelliger kanagurta, Selar crumenophthalmus, Decapterus russelli

and Amblygaster sirm), catch per unit effort, population parameters

1. Introduction

The term ‘small pelagic fishes’ refers to a diverse group of mainly planktivorous fishes that

share the same habitat, the surface layers of the water column, usually above the continental

shelf and in waters not exceeding 200m in depth. The small pelagic fishes can be defined as

the clupeoids (Engraulidae, Clupeidae), scads (Carangidae), mackerels (Scombridae), fusiliers

(Caesionidae), flying fish (Exocoetidae), halfbeaks (Hemiramphidae) and silversides

(Atherinidae). Fishes, such as long toms (Belonidae), and some of the scombrids, e.g. bullet

tunas (Auxis spp.) and shark, mackerel (Grammatorcynus bicarinatus) fall between the large

and small pelagic groupings (Dalzell P. 1988). Given the diversity of the small pelagic fishes,

only four dominant small pelagic species, namely; Selar crumenophthalmus, Rastrelliger

kanagurta, Decapterus russelli and Amblygaster sirm were emphasized to determine the

current status of dominant small species in Hinatuan Passage.

The fishing ground is shared by seven coastal municipalities namely; Placer, Taganaan,

Claver, Bacuag, Giqaquit, Socorro and Dapa, and a portion of Surigao City, Surigao del Norte.

It is one of the main fishing grounds which support the abundant fishery resources in the

region. Surigao del Norte had been abundant in fishery production that it ranked 4th in the year

2005-2007 and 3rd in 2006-2008 in marine, municipal fisheries top producing province in the

country (Bureau of Statistics Profile).

The surrounding municipalities rely heavily on its coastal and marine resources for food and

livelihood. But, these resources are being threatened by the proliferation of illegal fishing,

mangrove conversion, increasing siltation, degradation of marine habitats and other issues that

are adversely affecting marine production (retrieved from

http;//surigaofocas.wordpress.com/hipada/). The fishing ground is characterized by multi-gears

exploiting the diverse species, especially those dominant small pelagic fishes which

contributes 32% of the total production in the area. (This study).

In Caraga Region, National Stock Assessment Program (NSAP) catch and effort data

collection started in 1998 up to the present, focusing on the three major fishing grounds

namely; Surigao Strait, Dinagat Sound and Hinatuan Passage. However, this paper only

extracted the information regarding the dominant small pelagic fishes in Hinatuan Passage for

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International Journal of Fisheries and Aquatic Studies

ten years (2004-2013). Hence, there is a limited data regarding

the status of the fishery resources, particularly small pelagic

fishes, this paper aims to provide a baseline data for its proper

utilization and management.

1.1 Map of the Fishing Ground Hinatuan Passage is located on the northeast coast of the

Province of Surigao del Norte. It is called the eastern passage

with an estimated ground area of 240 square miles strategically

located at 1250 42’ east longitude and 100 55’ north latitude.

It is generally the main route of passengers and commercial

fishing vessels trading in the eastern coastal towns of

Mindanao. Three major fish landing centers were located in

Placer and Surigao City on the mainland of Surigao del Norte,

and in Dapa, an island municipality of Siargao Island. Three

trained enumerators were assigned in both mainland landing

centers and two other enumerators were assigned in Dapa.

2. Methodology

2.1. Landing Center/Sampling Sites

Data were extracted from the study conducted in Hinatuan

Passage during the period of January 2004 to December 2013.

Figure 1 shows the major and minor fish landing centers

established by the National Stock Assessment Program

(NSAP) in Caraga. These are Placer, Surigao del Norte, and

Surigao City in the mainland as major landing centers and

Dapa in Siargao island as the minor landing center.

Fig 1: Map of Surigao del Norte showing the study sites.

2.1.1 Data Collection

Catch and fishing efforts monitoring was done after every two

days at one day intervals following the nationwide monitoring

schedule. Fishermen were further interviewed on the gear type,

fishing location, total catch and the number of fishing efforts

exerted per fishing. Fish identification followed the National

Stock Assessment Program Guide to the Identification of

Marine Fishes (Allen and Swainston 1988). Unidentified

samples were brought to the Regional Office for further

identification. Assigned NSAP enumerators then took samples

from boat landed, then species were classified, weighed and

measured accordingly. Samples were measured from the tip of

the snout to the tip of the caudal fin or commonly called the

total length measurement type.

2.1.2 Boat and Gear inventory

The actual count of fishing boats and fishing gears were

conducted in 2004, 2009 and 2013 in sixty five coastal

barangays comprising the seven municipalities bordering

Hinatuan Passage. Interviews were done by NSAP field

enumerators as to the gear specification and operation.

2.1.3 Annual Catch Estimates

Catch and effort data served as the basis for estimates of the

total yield. The catch per unit of effort (CPUE) was the ratio

between the weight of the catch and effort required to obtain

the catch. For this study, fishing efforts of different gears were

standardized and a day of fishing operation served as a

common unit of fishing effort measurement. The estimated

production was computed using the equation:

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Estimated = Catch per Unit Effort x Annual Frequency x

Number of Gear Units Production (CPUE) of operation

2.1.4 Catch Composition and relative abundance

The catch composition is determined by gear type. Relative

abundance is ranked according to the number of fish species

represented as to how common or rare a fish species in relation

to other fish species.

2.1.5 Length Frequency

Length frequency (L/F) was analyzed using the ELEFAN

(Electronic Length Frequency Analysis) routine of the FiSAT

(FAO-ICLARM Stock Assessment Tool) copyright 2000-

2005, version 2.2. Growth of fishes is commonly described by

von Bertalanffy growth equation from the simple physiological

arguments, which is derived from the expression (Gayanilo,

F.C. et al. 1996):

L (t) – L∞ [1- e (-K (t-to))] … (5)

Where Lt, is the length of fish age, t. L∞ is the asymptotic size

or the asymptotic length of the mean size at which the fish

would grow if they were allowed to live and grow indefinitely,

e is the base of Maperrion logarithm, K is the growth constant

and to, the curve origin or the hypothetical age the fish would

attain at length zero, if it has always grown in a manner as

described by the von Bertalanffy equation. The components of

the instantaneous total mortality are shown in the following

expression,

Z = M + F … (6)

Where M, is the instantaneous natural mortality coefficient or

death caused by predation, old age, pollution, etc. and F is the

instantaneous fishing mortality coefficient or death by fishing.

M is estimated from Pauly’s empirical formula:

Log m=0.654 log k-1 0.28log L∞ + 0.463log T… (7)

Where, L∞ and K are the von Bertalanffy growth parameters

and T is the mean environmental temperature; 28.30 C (Dalzell

and Ganaden, 1987). These mortality components are also

expressed in the form of an index to determine the rate of

exploitation, i.e, E = F/Z … (8)

Where E is the exploitation rate, and F and Z are fishing and

total mortality coefficients.

3. Results

3.1. Fishing boats and fishers

Commercial fishing boats had 32 units in 2004, 20 units in

2009 and 31 units in 2013 (Table 1). A significant decrease in

2009 was observed due to transfer of fishing by some

commercial fishing boat operators to Manila Bay and Leyte

Gulf. Fish commands higher price in these areas as compared

to the Caraga Region (per communication).

For municipal fishing boats, a total of 2,573 were recorded in

2013 using motorized and non-motorized boats (Figure 2). Of

these, 76% were classified as motorized fishing boats using

marine engine ranging from 3 HP to 16 HP. The remaining

24% were classified as non-motorized. The total number of

fishers was 2,273 in which 78% engaged in full time fishing

and 22% were part-timers.

Table 1: Gear inventory conducted in 2004, 2009 and 2013 in seven coastal municipalities including Surigao

City fishing within Hinatuan Passage.

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Fig 2: Percentage composition of a) boats b) fishers in seven

municipalities bordering inatuan Passage in 2013.

3.2 Fishing gear inventory Table 1, shows the fishing gear inventory conducted in 2004,

2009 and 2013. Both commercial and municipal fishing gears

were operating in the area. Three types of commercial fishing

gears were prevalent namely; Danish seine, Ring net and

Bagnet with a total number of 31 units in 2004, 20 units in

2009 and 31 units in 2013. For municipal fishing gears, in

2004, 2009 and 2013, it has recorded a total of 8,317 units,

5,363 units and 3,805 units, respectively. These were

dominated by nets such as Drift Gillnet, Drive- in- net and

Bagnet which further classified into 12 types. Followed by

Beach Seine (2 units), Hook and Line (6 units), Spear gun (2

units) and others (4 units), respectively. A decrease of 35.52%

in 2009 and 29% in 2013 on fishing gear units was attributed

to some factors like shifting of fishing activities to mining and

other gears were not used anymore.

4. Annual Catch Estimates

Figure 3 shows the annual catch of both commercial and

municipal fishing gears. Commercial fishing gears contributed

only 8% of the total annual catch while municipal fishing

gears accounted 92% of the total production in the area from

2004 to 2013. The commercial fishery has reached a total

catch of 5,639.14 metric tons. During the years of operations,

high production were observed in 2005, 2010 and in 2011.

However, a decreasing trend for commercial production was

observed in 2012. Nevertheless, a rise in commercial

production was also noticed in 2013.

Municipal gears had an aggregated total catch of 84,809 metric

tons from 2004 to 2013. As shown in Figures 4, there was a

remarkable increase in the year 2008. Though it fluctuated in

2010, it significantly ascended upon reaching 2011 and 2013.

Fig 3: Annual Catch of Commercial Fishing Gears from 2004-2013.

Fig 4: Annual Catch of Municipal Fishing Gears rom 2004-2013.

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4.1 Landed Catch of Pelagic and Demersal

For the ten year period of study (2004-2013), Hinatuan

Passage recorded a total landed catch of 7,933 metric tons

from both the pelagic and demersal fisheries. Of the total, 43%

accounted for demersal fishes, 55% small pelagic fishes, 2%

large pelagic fishes and 0.002% miscellaneous group, Figure

5. Small pelagic fishes constituted a bigger portion than large

pelagic fishes since they were abundantly caught by

commercial Ring Net, Bagnet, Danish Seine and by municipal

fishing gears like Multiple hook and line, Hook and line, and

Drift gillnet.

Figure 6, illustrates the pelagic and demersal landings which

showed that the trend of both pelagic and demersal fisheries

has levelled off since 2004 to 2009, except for 2010 that small

pelagic fishes like Selar crumenophthalmus and Rastrelliger

kanagurta marked higher catch compared to demersal fishes.

This was mainly attributed to the fishing operation of Bagnet

in Hinatuan Passage in which their regular fishing ground was

in Surigao Strait.

Fig 5: Percentage composition of demersal, small pelagic and large pelagic.

Fig 6: Catch trend of pelagic and demesal fishery in Hinatuan Passage from 2004-2013.

4.2 Catch trend of four dominant small pelagic

Four small pelagic species dominated the landed catch in the

Hinatuan Passage from 2004 to 2013 which is presented in

Figures 7. It showed that Selar crumenophthalmus ranked first

in terms of dominance which has an upward trend that peaks in

the year 2012 and started to decrease in 2013. The lowest

catch landed was recorded in 2008.

Rastrelliger kanagurta showed a fluctuating trend, but in 2012

and 2013 recorded increasing. Moreover, Decapterus russelli

had a peak trend in 2010 which was still caught by Bagnet. On

the other hand, Amblygaster sirm had its peak landed catch in

2010. It was in the year 2010 that the small pelagic fishes had

noticeably the highest catch compared to almost all the years

from 2004 to 2013.

5. Species composition and relative abundance A total of 493 species under 185 genera which belongs to 85

families was recorded during the study period. The most

diverse species were the family Serranidae with 41 species,

followed by family Carangidae (37), Nemipteridae (37),

Scaridae (35) and Lethrinidae (29), respectively. The other

five families were belonged to invertebrate such as Dasyatidae,

Loliginidae, Octopodidae, Portunidae and Sepiidae, Figure 8.

Landed catch composition caught by various gear was

dominated by family Carangidae, Scombridae, Mullidae,

Clupeidae and Leiognathidae, Figure 9. The bulk of catches

were mainly small pelagic fishes such as Selar

crumenophthalmus comprised 8.93% of the total landed catch

followed by Rastrelliger kanagurta (8.03%), Amblygaster sirm

(Clupeidae, 8%). Demersal fish species Upeneus sulphureus

(Mullidae, 7.45%) ranked fourth and the rest of the species

were Decapterus russelli (6.77%), Leiognathus bindus

(3.61%) and others, (46.20%), Table 2.

On the other hand, the list of pelagic fish species is presented

in Table 3. It showed that twenty-two species were recorded

for pelagic fish and Carangidae family shared 42.75%,

Scombridae 26.44%, Clupeidae (16.04%), Engraulidae

(5.80%), Exocoetidae (2.75%) and others.

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Table 2: Top ten dominant species caught by various fishing gears in Hinatuan Passage

2004-2013

Family (%)

Carangidae Selar crumenopthalmus Matambaka, Adlo 8.93

Scombridae Rastrelliger kanagurta Anduhaw 8.03

Clupeidae Amblygaster sirn Hawol hawol 7.8

Mullidae Upeneus sulphureus Salmonite 7.45

Carangidae Decapterus russelli Bodloy 6.77

Priacanthidae Priacanthus tayenus Lagat 4.02

Leiognathidae Leiognathus bindus Sapsap 3.61

Engraulidae Encrasicholina heteroloba Bolinaw 2.64

Scombridae Rastrelliger faughni Andunaw 2.33

Gerridae Pentaprion longimanus Latab 2.22

Others 46.2

Total 100

Species Local name

Table 3: Landed Catch by Family of Pelagic in Hinatuan Passage from 2004-2013.

Rank Family Catch (MT) % Share

1 Carangidae 1,931.31 42.75

2 Scombridae 1,194.56 26.44

3 Clupeidae 724.82 16.04

4 Engraulidae 262.20 5.80

5 Exocoetidae 124.12 2.75

6 Loliginidae 117.98 2.61

7 Belonidae 57.59 1.27

8 Hemiramphidae 49.24 1.09

9 Istiophoridae 17.64 0.39

10 Sepiidae 13.68 0.30

11 Emmilitchydiae 9.79 0.22

12 Menidae 7.94 0.18

13 Dusummieridae 5.88 0.13

14 Coryphanidae 0.49 0.01

15 Gonorynchidae 0.15 0.00

16 Sphyraenidae 0.13 0.00

17 Octopodidae 0.11 0.00

18 Xipphidae 0.10 0.00

19 Megalopidae 0.10 0.00

20 platycephalidae 0.05 0.00

21 Elopidae 0.03 0.00

22 Epphippidae 0.01 0.00

TOTAL 4,517.91 100.00

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20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

MT

Selar crumenophthalmus

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20.00

40.00

60.00

80.00

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120.00

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

MT

Rastrelliger kanagurta

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50.00

100.00

150.00

200.00

250.00

300.00

350.00

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

MT

Amblygaster sirm

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20.00

40.00

60.00

80.00

100.00

120.00

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

MT

Decapterus russelli

Figure 7. Landed catch of small pelagic fishes; A) Selar crumenophthalmus, B)

Rastrelliger kanagurta, C) Decapterus russelli and D) Amblygaster sirm in Hinatuan

Passage from 2004 to 2013.

a)

b)

c)

d)

Fig 8: Most diverse fish families composition in Hinatuan Passage from 2004-2013.

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Fig 9: Most abundant fish families in Hinatuan Passage caught by various gears, 2004-2013.

5.1 Catch Composition of four dominant small pelagic by

gear

5.2 Commercial Gears

5.2.1 Bagnet

As mentioned earlier that the small pelagic were caught by

both municipal and commercial fishing gears. Figure 10,

presents the catch composition of dominant small pelagic by

gear from 2007-2013. Bagnet had caught small pelagic fishes

consisting Amblygaster sirm (37.57%), Encrasicholina

heteroloba (25.56%), and Stolephorus indicus. Significant

species also included Uroteuthis bartachi (squid) in the catch

and the rest were scads and mackerels.

Fig 10: Mean percentage of species composition caught by Bagnet from 2007-2013.

5.2.2 Danish seine

As observed the main catch of Danish seine were a

combination of demersal and small pelagic fishes. Upeneus

sulphureus had the biggest share with 32.51% from 2007-2013

followed by small pelagic fishes Decapterus russelli, S.

crumenophthalmus and alongside with the common small

pelagic fishes like Rastrelliger kanagurta, Selaroides

leptolepis, Rastrelliger faughni and others. The rest of the

landed catches were demersal species such as L. bindus, P.

longimanus and L. elongates, Figure 11.

Fig 11: Mean percentage of species composition caught by Danish seine from 2007-2013.

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5.2.3 Ring net

Ring net had consistently caught small pelagic fishes like

Amblygaster sirm which held the biggest share of up to

39.79%, followed by Rastrelliger kanagurta 17.26%, Selar

crumenophthalmus 10.43%, Decapterus macrosoma 7.62%,

Decapterus russelli 5.85% and family tuna fishes such as

Auxis thazard, Thunnus tonggol, Auxis rochei and Euthynnus

affinis from 2007-2013, Figure 12.

Fig 12: Mean percentage of species composition caught by Ring net from 2007-2013.

5.3 Municipal Fishing Gears 5.3.1 Multiple hook and line

One of the important major municipal fishing gears is the

Multiple hook and line which contributed the biggest share of

production in the area. This gear had caught mainly pelagic

fish and few demersal fish from 2007 to 2013 consisting Selar

crumenophthalmus with an average percentage of 43.52%,

Figure 13.

Fig 13: Mean percentage of species composition caught by multiple hook & line from 2007-2013.

5.3.2. Drift gill net and Bottom Gillnet

The catches of Drift gillnet were mostly small pelagic fishes

like Rastrelliger kanagurta (29.81%), Amblygaster sirm

(8.39%), Hemiramphus far and Tylosurus crocodilus. Unlike

Drift gillnets, Bottom gillnets catches mainly on demersal

fishes such as Siganus canaliculatus, S. virgatus and others,

Figure 14.

Fig 14: Mean percentage of species composition caught by Drift gillnet and Bottom gillnet from 2007-2013.

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5.3.3 Bagnet

Municipal Bagnet had dominantly caught small pelagic fishes

such as Amblygaster sirm (48.29%), followed by Uroteuthis

bartschi (27.98%) and the lowest was Spratelloides gracilis

(0.23%). It was noticeable that squid (Uroteuthis bartschi) was

also caught by this particular gear from 2007 to 2013, Figure

15.

Fig 15: Mean percentage of species composition caught by municipal Bagnet from 2007-2013.

6. Seasonality Four dominant commercially important small pelagic species

monthly catch trend or seasonality from 2007-2013 is

presented in Figures 16. It shows that Rastrelliger kanagurta

vary its peak per year, except for 2010 and 2012 which marked

the primary peaks in October and November while July and

August as secondary particularly in 2007 and 2011. While lean

months recorded in April and May. In addition, Selar

crumenophthalmus was the same with R. kanagurta with peak

months occurring in October and November while the lean

months were recorded in May and June. Furthermore,

Amblygaster sirm peak during September, October and

November while Decapterus russelli, occurred high during the

months of July to August.

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Fig 16: Seasonality pattern of small pelagic a) Rastrelliger kanagurta, b) Selar crumenophthalmus c) Decapterus russelli d) Amblygaster sirm in

Hinatuan Passage for the period of 2004 to 2013.

7. Length Frequency Distribution

The length distribution for Rastrelliger kanagurta, Selar

crumenophthalmus, Decapterus russelli and Amblygaster sirm

are presented in Figures 17-20. To evaluate the size selectivity

of Danish seine and other major gears operating in Hinatuan

Passage, the length frequency distributions of dominant fish

species landed were compared.

Fig 17: Length frequency distribution of Rastrelliger kanagurta caught by a) Danish seine, b) Ring net and c) Drift gillnets in Hinatuan Passage

for the period of 2012.

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7.1 Rastrelliger kanagurta

R. kanagurta was caught with Danish seine, Ring net and Drift

gillnet. Danish seine and Ring net captured the size ranging

from 11.25 cm-28.25 cm, respectively. This showed that 75%

of the catches were caught immature below size at first

maturity (Lm) of 23cm. Meanwhile, Drift gillnet was among

the obviously selective gear, hence this gear caught bigger

sizes ranging from 22.75-28.75cm, Figure 17.

7.2 Selar crumenophthalmus

Danish seine and drift gillnet was the common fishing gears

which caught S. crumenophthalmus. Still, Danish seine was

catching juvenile sizes ranging from 10.75 cm-25.75 cm. With

this, 78% were caught immature, which is below the length at

first maturity of 21.5cm. Obviously, Drift gillnet is a selective

gear that catches a bigger size of fish, Figure 18.

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% Freq

Length (cm)

Immature 76%

Immature 16%

a) DS

b) DGN

Fig 18: Length frequency distribution of Selar crumenophthalmus in Hinatuan Passage caught by a) Danish seine (DS) and b) Drift gillnet

(DGN) for the period of 2012.

0

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Length (cm)

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% Freq

Length (cm) Lm= 18 cm

Immature 90%

Immature 83%

a) RN

b) DS

Fig 19: Length frequency distribution of Decapterus russelli in Hinatuan Passage caught by a) Ring net (RN) and b) Danish seine (DS) for the

period of 2012.

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7.3 Decapterus russelli

The same true with D. russelli, both Danish seine and Ring net

caught length sizes from 9.25 cm to 22.25 cm, respectively.

Figure 19 revealed that these two gears targeted D. russelli,

where 90% of the catches of Danish seine were caught

immature while 83% of Ring net with which sizes were lower

than its length at first maturity of 18 cm.

7.4 Amblygaster sirm

The landed size of A. sirm caught by Ring net ranged from

5.25 cm to 22.25 cm. The length at first maturity was 15 cm.

Most of the catches were caught at immature size 72% and

75%, respectively, Figure 20.

Fig 20: Length frequency distribution of Amblygaster sirm caught by Ring net for the period of a) 2011 and b) 2012.

8. Population Parameters

Assessment models for tropical multi species stock require

estimates of population parameters of most abundant species

(Armada, 1996). In the case of Hinatuan Passage, three major

gears provided the basis for estimating the population

parameters of four dominant small pelagic namely; S.

crumenophthalmus, Rastrelliger kanagurta, Decapterus

russelli and Amblygaster sirm from the year of observations

2004 to 2013. The four dominant small pelagic fishes

constituted an average of about 32% of the total landed catch.

Table 4, provided the estimated population parameters of the

four dominant small pelagic from 2004-2013. Based on the

analysis using the FAO-ICLARM Stock Assessment Tool

(FiSAT) software, it showed that all species varied their values

in L∞, K, and other parameters from year to year. The results

were compared to the growth parameter values under the

Fishbase and Lavapie-Gonzales, et al. Refer to Table 5 for

guidance and reference to the analysis.

8.1 Growth

The growth parameters L∞ and k for Rastrelliger kanagurta

ranges from 27.66 to 35.18cm and 1.07yr1-1.6yr1, respectively.

The k values indicate a high growth rate in 2012 (1.6), with

growth performance indices (ᴓ’) ranged from 3.02-3.28. For S.

crumenophthalmus L∞ and K ranges from 26.2-29.4 and

1.1yr1-1.6yr1, respectively. The k values showed high growth

rates recorded in 2008 and 2011 with growth performance

indices (ᴓ’) ranged from 2.9-3.14. For D. russelli, its L∞ and

K ranging from 21.8-24.3 and 1.03-1.5, respectively. Lastly, A.

sirm, exhibited L∞ and K ranged from 24.68-26.3 and 1.05y1-

1.4, respectively, with growth performance indices (ᴓ’) ranged

from 2.86-2.94.

8.2 Mortality

The estimates for mortality parameters Z, M, and F are

presented in Table 3. R. kanagurta, S. crumenophthalmus, D.

russelli and A. sirm recorded total mortality coefficient ranged

from 3.61 yr1 to 14.41 yr1, where fishing mortality is higher

than natural mortality. The highest fishing mortality for R.

kanagurta was 7.88, S. crumenophthalmus 6.29, D. russelli 5.1

and A. sirm 12.2.

9. Exploitation Rates

Figure 21, shows the exploitation value distribution of four

dominant small pelagic species. For Rastrelliger kanagurta

had exploitation values ranged 0.54-.81, Selar

crumenophthalmus 04-0.72, Decapterus russelli 0.53-0.71 and

Amblygaster sirm 0.5-0.84, respectively. All exploitation rates

exhibited beyond the optimum level indicating over-

exploitation except for S. crumenophthalmus in 2004 with 0.40

which is below the optimum level.

~ 299 ~


Table 4: Population parameters of four dominant small pelagic species from 2004-2013.

Species

Year

F/Gear

L∞(cm)

K (year-1)

O’

Z

M (year-1)

F

E

R.kanagurta 2004 Merged 35.18 1.2 3.16 8.02 1.93 6.1 0.76 2005 Merged 32.06 1.07 3.04 9.71 1.83 7.88 0.81 2006

2007 Merged Merged

30.5 31

1.26 1.23

3.06 3.07

4.93 4

2.07 2.03

2.86 2.97

0.58 0.59

2008 DS 29.45 1.25 3.04 5.17 2.08 3.09 0.6 2009 DS 30.05 1.2 3.04 4.36 2.01 2.35 0.54 2010 DS 30.4 1.5 3.14 9.1 2.32 6.78 0.75 2011 DS 31 1.1 3.02 5.66 1.88 3.78 0.67 2012 DS 34.5 1.6 3.28 8.45 2.34 6.11 0.72 2013 DS 27.66 1.5 3.06 5.97 2.38 3.59 0.6 S. crumenophthalmus 2004 Merged 27.9 1.3 3.0 3.61 2.16 1.45 0.40 2005 Merged 27.96 1.2 2.97 5.6 2.05 3.55 0.63 2006

2007 Merged Merged

28.43 28.9

1.2 1.3

2.99 3.04

4.89 6.19

2.04 2.14

2.85 4.05

0.58 0.65

2008 Merged 29.2 1.6 3.14 8.74 2.45 6.29 0.72 2009 MHL 29.4 1.5 3.12 7.15 2.39 4.76 0.67 2010 DS 28.7 1.5 3.09 6.24 2.36 3.88 0.62

2011 DS 26.2 1.6 3.04 7.53 2.52 3.01 0.66 2012 DS 27.91 1.1 2.91 4.14 1.93 2.21 0.53 2013 DS 27.5 1.3 2.9 4.81 2.17 2.64 0.55

D. russelli 2004 Merged 23.54 1.03 2.76 6.79 1.95 4.84 0.71 2005 Merged 23.7 1.15 2.81 4.71 2.09 2.62 0.56 2006 Merged 21.8 1.15 2.74 5.25 2.14 3.11 0.53 2007 Merged 21.8 1.2 2.46 6.5 2.2 4.3 0.66 2008 DS 22.4 1.5 7.63 2.53 5.1 0.67 2009 DS 24.3 1.3 2.88 7.09 2.25 4.84 0.68 2010 Insufficient data 2011 DS 23.4 1.1 2.76 4.72 2.05 2.67 0.57 2012 DS 24.3 1.3 2.89 5.97 2.25 3.72 0.62 2013 DS 23.5 1.3 2.86 6.65 2.27 4.38 0.66

A. sirm 2004 Merged 24.68 1.36 2.92 4.62 2.31 2.31 0.5

2005 Merged 24.68 1.36 2.92 13.99 2.3 11.7 0.84 2007 Merged 26.3 1.05 2.86 6.42 1.91 4.51 0.7 2008 DS 25 1.4 2.94 7.19 2.34 4.85 0.68 2009 DS 24.81 1.4 2.94 4.92 2.35 2.57 0.52 2012 Merged 24.8 1.4 2.94 14.41 2.26 12.2

1 0.84

2013 No data

Table 5: Comparative values for Growth Parameters.

Species Year L∞(cm) K Location

R.kanagurta 2004 35.18 1.2 3.16 This study

2005 32.06 1.07 3.04 This study

2006 30.5 1.26 3.06 This study

2007 31 1.23 3.07 This study

2008 29.45 1.25 3.04 This study

2009 30.05 1.2 3.04 This study

2010 30.4 1.5 3.14 This study

2011 31 1.1 3.02 This study

2012 34.5 1.6 3.28 This study

2013 27.66 1.5 3.06 This study

2013 27.83 1.5 3.07Marudu Bay, Sabah,

Malaysia

1986-1987 31.9 2 Leyte Gulf

1983-1986 37.9 1 Samar Sea

27.7 1.65 3.01 Guimaras Strait

26.5 1.6 3.05 Samar Sea

28 1.55 3.08 Palawan

S. crumenophthalmus 2004 27.9 1.3 3 This study

2005 27.96 1.2 2.97 This study

2006 28.43 1.2 2.99 This study

2007 28.9 1.3 3.04 This study

2008 29.2 1.6 3.14 This study

2009 29.4 1.5 3.12 This study

2010 28.7 1.5 3.09 This study

2011 26.2 1.6 3.04 This study

2012 27.91 1.1 2.91 This study

2013 27.5 1.3 2.9 This study

2.96

25.4 1 2.81 Guimaras Strait

26.5 1.25 2.94 Tayabas Bay

24.6 1.5 Leyte Gulf

Ø'

~ 300 ~


Continued-

Species Year L∞(cm) K Location

D. russelli 2004 23.54 1.03 2.76 This study

2005 23.7 1.15 2.81 This study

2006 21.8 1.15 2.74 This study

2007 21.8 1.2 2.46 This study

2008 22.4 1.5 This study

2009 24.3 1.3 2.88 This study

2011 23.4 1 2.76 This study

2012 24.3 1.3 2.89 This study

2013 23.5 1.3 2.86 This study

33 0.45 2.69 Palawan

35.1 1.4 3.24 Camotes Sea

30 0.54 2.69 Manila Bay

A. sirm 2004 24.68 1.36 2.92 This study

2005 24.68 1.36 2.92 This study

2007 26.3 1.05 2.86 This study

2008 25 1.4 2.94 This study

2009 24.81 1.4 2.94 This study

2012 24.8 1.4 2.94 This study

2009 24.81 1.4 2.94 This study

27.3 0.86 2.81 Palawan

29 1.3 3.04 Camotes Sea

31 1.35 3.11 Camotes Sea

Ø'

~ 301 ~


Fig 21: Exploitation values of a) Rastrelliger kanagurta, b) Selar crumenophthalmus c) Decapterus russelli and d) Amblygaster sirm from 2003-

2013.

10. Discussion

The number of fishing gears in Hinatuan Passage in 2004 was

8,317 units with 27 types. These numbers were much higher

than the study conducted in Sorsogon Bay with 6,012 units

belonging to 19 types only in 2001 (Olanio, et al. 2009). The

multi-gears in the area is associated with the continuous

development of fishing operation and efficiency of the gear

specially spear gun, hook and line, net and other occasional

fishing gears.

The downward trends for commercial production were

observed, particularly in 2007 and in 2012. The declined of the

catch were mainly attributed to the reduced operation of some

Danish seine, Ring net and Bag net due to high maintenance

cost of the vessels and nets which worn out in the course of

time. Furthermore, some fishing boats transferred their fishing

location to other fishing grounds like Manila Bay and Leyte

Gulf, where fish commands a higher price compared to the

nearby markets in Caraga Region.

Moreover, Local Government Units (LGU’s) persistently

implemented fishery laws in apprehending commercial fishing

operations within the municipal waters. Further, climatic

condition in the area characterized by big waves and strong

currents hampered fishing operation as well.

The annual catch trend of the municipal fishing gears were an

upward trend from 2005 – 2008 however, a downward trend

was recorded in 2010. This was attributed to the shift of fishers

into mining employment, particularly those from the

municipalities of Claver and Taganaan, Surigao del Norte. The

trend significantly ascended upon reaching 2011 to 2013 since

there were only few commercial fishing boats operating as a

result of the persistent apprehension of law enforcement in the

area. In addition, the upward trend was also attributed to the

consistent operation of multiple hook & line, hook and line

(single) and other gears. In addition, the shifting of some

commercial gears to municipal gears like Troll line and

Multiple hook & line targeting tuna species have given

possible chances for the small fishers to fish within municipal

waters.

The fisheries on small pelagic fishes comprise an important

segment in the region’s fishery industry. In this study, small

pelagic fishes comprise 55% of the total fisheries production in

Hinatuan Passage. In the Philippines, small pelagic fisheries

contributed 35% of the total fisheries production in 2001.

Countrywide assessments of small pelagic fisheries of the

Philippines are given, among others, in the studies of various

authors Munro (1986); Calvelo and Dalzell (1987); & Dalzell

and Ganaden (1987).

The main fishing gears that caught small pelagic fishes

belonged to the commercial sector, which used various fishing

gears. Among these gears were Bagnet and Ring net, both

gears caught 90% of small pelagic fishes and Danish seine

with 34%, whereas municipal gears included multiple hook

and line which caught 85% of small pelagic fishes, drift gillnet

and bottom gillnet with 56% and Bagnet municipal with 71%,

respectively.

The four dominant small pelagic fishes appeared to be

seasonal on particular months of September to November. This

coincided with the biological production of small pelagic

fishes which are highly seasonal, being influenced by

environmental conditions most notably by monsoon winds

(Pauly and Navaluna 1983; Navaluna and Pauly 1988; Dalzell

and Corpuz 1990).

In this study, the length frequency distributions of S.

crumenophthalmus and D. russelli were ranging from

10.75cm-25.75 and 9.75cm-22.25cm. The length sizes were

slightly larger than those studies conducted by Philbrick

(1987), White (1982) and Ingles and Pauly (1984) which

ranged from 7 cm- 27 cm and 7 cm-22 cm in the area of

Marinduque. Apart from that, Amblygaster sirm in Sri Lanka

was ranging from 9.0 cm – 22.0 cm (W.P.N. Karunasinghe, et

al. 1991), whereas in this study sizes were ranging from 5.25

cm- 22 cm. Rastrelliger kanagurta, on the other hand ranged

from 11.5cm - 26.5 cm in Marudu Bay, Sabah, Malaysia

(Amin, S.M.N, et al. 2013), in contrast this study has sizes

ranging from 11.5 cm – 28 cm. Comparing the size ranged of

catches from the three major fishing gears catching small

pelagic fishes with length at first maturity of the four dominant

small pelagic fishes, it appeared that these gears has negative

impact on the sustainability of capture fisheries. S.

crumenophthalmus for instance, attained maturity at 21.5cm,

D. russelli at 18cm, A.sirm at 16.5cm and R. kanagurta at

23cm, these are clear indications that immature fishes are very

vulnerable to be caught with these gears. In contrast, Multiple

hook and line and Drift gillnet are selective that caught bigger

sizes of fish and could highly be commendable to use for

sustainable reasons.

The comparative values for the growth parameters is given in

Table 5. In 2013, Rastrelliger kanagurta had the same k values

with the values obtained in Marudu Bay, Sabah, Malaysia

(Amin, S.M.N, et al. 2013), while L∞ was very closed to the

aforementioned L∞ values of the study. Further, each growth

coefficient index was within the range of other studies

conducted in Palawan, Samar, Guimaras Strait and Leyte.

For Selar crumenophthalmus, L∞ and K values were closer to

the previous works of Lavapie-Gonzales in the areas of Leyte

Gulf, Guimaras Strait and Tayabas Bay.

On the other hand, L∞ and K values of Decapterus russelli

was ranging from 21.8-24.3 and 1.03-1.5, respectively. The k

values showed high growth rates recorded in 2008. However,

the k value obtained in the study is higher than those in

~ 302 ~


Palawan and Manila Bay, 0.45 and 0.54, respectively. The

difference of k values may be due to environmental parameters

and the type of fishing gears used.

In addition, Amblygaster sirm had higher K values than those

in Palawan and Manila Bay except for Camotes sea with 1.4.

Almost all growth coefficient (ᴓ’) values for this species fall

within the ranged in other areas of the Philippines.

Generally, the findings on the K values in this study correlates

with the statement of Dalzell and Corpuz (1990) that small

pelagic fishes usually attain a maximum weight of less than

500g and are characterized by short life span and fast growth

rates and subsequent high natural mortality, however the

results indicated that fishing mortality were higher than natural

mortality.

With this, all species investigated had an optimum value of

0.53-0.84. Accordingly, species-specific assessment of small

pelagic fishes in various fishing grounds (Ingles and Pauly,

1984; Corpuz, et al., 1985; Lavapie-Gonzales, et al., 1997)

registered a very high exploitation rate over 0.50 ratios which

is an indicative of over fishing. Gulland (1971) has suggested

that in an optimally exploited stock, fishing mortality should

be about equal to natural mortality, resulting in a fixed Eopt =

0.5. Based on the results, E-values were above the optimum

values of 0.5. Hence, the stock can be considered as over

exploited. Further, immature sizes below the length at first

maturity (Lm) may also result to high fishing mortality of the

stocks.

The exploitation rate (E) is estimated at 0.56, which is higher

than the optimum value of 0.5. Hence, the stock can be

considered as over-exploited. According to Froese overfishing

can be prevented by following certain rules, such as by

catching fishes that have reached their optimum length, which

is usually a bit larger than the length at first maturity, however,

the spawning fish must be avoided. Moreover, large females

must be avoided as they are more fecund and a minimum catch

length can be set such that more than 90% of the individuals

get at least one chance to reproduce before being caught as

overfishing can be stopped if all the fishes get an equal chance

to reproduce before capture. In this study it was observed that

the majority of the landed catch by Danish seine, Ring net and

Bagnet were immature or juvenile fishes and this could

tremendously affect the healthy survival of the stock. If any

population is affected by overfishing, the stock can easily

collapse if proper attention is not given.

11. Summary The most important small pelagic fishes in Hinatuan Passage

are R. kanagurta, S. crumenophthalmus, D. russelli and A.

sirm. Multi-gears were exploiting the stocks in the Hinatuan

Passage from both commercial and municipal fishing sectors.

55% of the landed catch were small pelagic fishes, of which

32% shared by R. kanagurta, S. crumenophthalmus, D. russelli

and A. sirm.

According to Froese, overfishing can be prevented by

following certain rules, such as by catching fishes that have

reached their optimum length, which is usually a bit larger

than the length at first maturity. However, the spawning fishes

must be avoided. Moreover, large females must be avoided as

they are more fecund and a minimum catch length can be set

such that more than 90% of the individuals get at least one

chance to reproduce before being caught as overfishing can be

stopped if all the fishes get an equal chance to reproduce

before capture.

With the length sizes, about 75% of small pelagic fishes were

caught before they reach the size of maturity. Most of the

small size fishes were caught by Ring nets, Danish seines and

Bagnets. However, bigger sizes were caught by Multiple hook

and lines and Drift gillnets which implies these gears are

friendly gears. Exploitation values already exceeded the

optimum level. In this study it was observed that the majority

of the landed catch by Danish seine, Ring nets and Bagnets

were immature or juvenile fishes and this could tremendously

affect the healthy survival of the stock. If any population is

affected by overfishing, the stock can easily collapse if proper

attention is not given.

12. Acknowledgment

We are so grateful for the assistance of BFAR-Central Office

thru Director Atty. Asis G. Perez for the financial support and

continuity of the project. To Mr. Noel C. Barut of National

Fisheries and Development Institute for his guidance being the

National NSAP Coordinator and Dr. Mudjekeewis D. Santos,

Asst. National NSAP Coordinator. To Dr. Nerio G. Casil,

BFAR-Caraga Regional Director and top management, and his

predecessor Director Alauya R. Olama, CESO IV for their

regular support for the sustained implementation of the

National Stock Assessment Program (NSAP). To our mentors,

Prof. Nygiel M. Armada and Mr. Gerry Silvestre for sharing

their expertise in data analysis. We also acknowledge the

legacy of the long-time NSAP, Project Leader, the late Miguel

O. Baay for his untiring efforts and exemplary supervision in

molding the NSAP team technically trained.

Furthermore, our warmest commendation to our former NSAP

Asst. Project Leader, Edgardo P. Balambao, current data

encoder; Renante M. Bao, for his untiring efforts in data

encoding, field enumerators namely; Nobey Epis, Sabino

Exclamador, Restituto Bautista, Nelson Culla, Cirilo

Cadelinña, Florendo Bernaldez, Charito Jandayan, Alvin

Balansag, Energito Balaba and Renato Abreu for their

perseverance and dedicated work in data gathering. All

fishermen for their support and above all our Almighty God

for his unconditional love throughout the project.

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