issn: 2347-5129 dominant small pelagic in hinatuan passage caraga region…€¦ · ·...
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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
Bureau of Fisheries and Aquatic
Resources- Caraga Region
Peṅaranda St., Surigao City,
Philippines
Laila M Holoyohoy
Bureau of Fisheries and Aquatic
Resources- Caraga Region
Peṅaranda St., Surigao City,
Philippines
Eunice C Bognot
National Fisheries Research and
Development Institute (NFRDI)
101 Mother Ignacia Ave.,
Quezon City, Philippines
Correspondence
Joyce M Baclayo
Bureau of Fisheries and Aquatic
Resources- Caraga Region
Peṅaranda St., Surigao City,
Philippines
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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International Journal of Fisheries and Aquatic Studies
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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International Journal of Fisheries and Aquatic Studies
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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International Journal of Fisheries and Aquatic Studies
-
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
-
20.00
40.00
60.00
80.00
100.00
120.00
2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
MT
Rastrelliger kanagurta
-
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
-
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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International Journal of Fisheries and Aquatic Studies
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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International Journal of Fisheries and Aquatic Studies
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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International Journal of Fisheries and Aquatic Studies
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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International Journal of Fisheries and Aquatic Studies
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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International Journal of Fisheries and Aquatic Studies
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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1
2
3
4
5
6
7
8
9
10
.75
11
.25
11
.75
12
.25
12
.75
13
.25
13
.75
14
.25
14
.75
15
.25
15
.75
16
.25
16
.75
17
.25
17
.75
18
.25
18
.75
19
.25
19
.75
20
.25
20
.75
21
.25
21
.75
22
.25
22
.75
23
.25
23
.75
% Freq
Length (cm)
0
5
10
15
20
25
10
.75
11
.25
11
.75
12
.25
12
.75
13
.25
13
.75
14
.25
14
.75
15
.25
15
.75
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.25
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.75
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.25
17
.75
18
.25
18
.75
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.25
19
.75
20
.25
20
.75
21
.25
21
.75
22
.25
22
.75
23
.25
23
.75
24
.25
24
.75
25
.25
25
.75
% 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
5
10
15
20
25
9.2
5
9.7
5
10
.25
10
.75
11
.25
11
.75
12
.25
12
.75
13
.25
13
.75
14
.25
14
.75
15
.25
15
.75
16
.25
16
.75
17
.25
17
.75
18
.25
18
.75
19
.25
19
.75
20
.25
20
.75
21
.25
21
.75
% Freq
Length (cm)
-
2.00
4.00
6.00
8.00
10.00
12.00
14.00
9.7
5
10
.25
10
.75
11
.25
11
.75
12
.25
12
.75
13
.25
13
.75
14
.25
14
.75
15
.25
15
.75
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.25
16
.75
17
.25
17
.75
18
.25
18
.75
19
.25
19
.75
20
.25
20
.75
21
.25
21
.75
22
.25
% 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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International Journal of Fisheries and Aquatic Studies
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.
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International Journal of Fisheries and Aquatic Studies
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 12.21
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'
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International Journal of Fisheries and Aquatic Studies
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'
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International Journal of Fisheries and Aquatic Studies
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
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International Journal of Fisheries and Aquatic Studies
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.
13. References
1. Allen GR, Swainston R. The marine fishes of North
Western Australia. A field guide for Anglers and Divers,
1988.
2. Amin SMN, Mohd Azim MK, Fatinah SNJ, Arshad A,
Rahman MA, Jalal KCA. 2014. Population Parameters of
Rastrelliger kanagurta (Cuvier, 1816) in the Marudu Bay,
Sabah, Malaysia.
3. Armada NB. Capture Fisheries in San Pedro Bay. In
Resource and Ecological Assessment of San Pedro Bay,
Philippines. IMFO Technical Report no. 16. Institute of
Marine Fisheries & Oceanography, College of Fisheries,
UP Visayas, Miag-ao, Iloilo, Philippines, 1996.
4. Armada NB. Fish Resources Assessment and
Management Recommendations for Davao Gulf, 334-335
p. In DA-BFAR (Department of Agriculture-Bureau of
Fisheries and Aquatic Resources). In turbulent seas. The
Status of Philippine marine fisheries. Coastal Resource
Management Project, Cebu City, Philippines, 2004, 378.
5. Barut NC, Santos MD, Garces LR. Overview of
Philippine marine fisheries. In D.A. BFAR (Department
of Agriculture-Bureau of Fisheries and Aquatic
Resources). In turbulent seas. The status of Philippine
marine fisheries. Coastal Resource Management Project,
Cebu City, Philippines, 2004, 28.
~ 303 ~
International Journal of Fisheries and Aquatic Studies
6. Beddington J, Cooke J. 1983. The potential yield of fish
stocks. FAO Fish. Tech. Pap, 242, 47.
7. Bureau of Agricultural Statistics (BAS) Profile. 2009.
8. Calvelo R, Dalzell P. A review of the recent status of
stocks of round scads in the Philippines IPFC/87/Sym/IV.
Inf.9. Paper presented at the Indo-Pacific Fishery
Commission. Symposium on the exploitation and
management of marine fishery resources in the South east
Asia, 1987.
9. Corpus A, Saeger J, Sambilay V. Jr. Population
parameters of commercially-important fishes in the
Philippine waters. College of Fisheries, University of the
Philippine, Quezon City, Philippines. Tech. Rep. Dept.
Mar. Fish. 1985; 6:99.
10. Dalzell P, Ganaden. A Review of the Fisheries for Small
Pelagic in Philippines Waters. Bureau of Fisheries and
Aquatic Resources. Tech, Paper Series. 1987; X(1):58.
11. Dalzell, P. Chapter 5. Small Pelagic Fishes, 1988, 98.
12. Dalzell P, Corpuz PV. The present status of small pelagic
fisheries in the Philippines, p. 25-51. In C.R. Pagdilao and
C.D. Garcia (eds.) Philippine tuna and small pelagic
fisheries: status and prospects for development. Philippine
Council for Aquatic and Marine Research and
Development, Los Baṅios, Laguna. Book Series 0711
990, 1990, 160.
13. Edralin DT, Ganaden S, Peter Fox. A comparative study
of fish mortality rates in moderately and heavily fished
areas in the Philippines. Contributions to the tropical
fisheries biology. Papers presented by the participants at
the FAO/DANIDA Training courses on fish stock
assessment in the tropics. Hirtshals, Denmark 5-30 May
1986 and Manila, Philippines 12 January-6 February 1986
Denmark Funds-In-Thrust, GCP/INT/392/DEN, Food and
Agriculture Organization of the United Nations, Rome,
1988, 1988.
14. Froese R, Pauly D. (eds.). Fish Base. World Wide Web
electronic publication, 2002. www.fishbase.org, version
2002.
15. Froese R. Keep it simple: three indicators to deal with
overfishing. Fish and Fisheries 2003; 5:86-91.
16. Gayanilo FC. Sparre P, Pauly D. The FAO-ICLARM
Stock Assessment Tools (FiSAT) User’s Guide. FAO
Computerized Information Series (Fisheries) No. 8 FAO
Rome, 1996, 126.
17. Gulland J. The Fish Resources of the Oceans. FAO
Fishing Network Ltd. Survey, England, 1971.
18. Ingles J, Pauly. An atlas of the growth, mortality and
recruitment of Philippine fishes. ICLARM Tech. Rep.
1984; 13:127p
19. Karunasinghe WPN, Wijeyaratne MJS. Population
dynamics of trenched sardine Amblygaster sirm
(Clupeidae) in the Western Coastal waters of Sri Lanka,
1991.
20. Kura Y, Revenga C. Fishing for Answers: Making Sense
of the Global Fish Crisis. World Resources Institute,
Washington, DC.
21. Lavapie-Gonzales FS, Ganaden R, Gayanilo FC. Jr. Some
population parameters of commercially-important fishes
in the Philippines. Bureau of Fisheries and Aquatic
Resources, Quezon City, Philippines, 1997, 114.
22. Navaluna N, Pauly D. Seasonality in the recruitment of
Philippine fishes as related to monsoon wind patterns, p.
In A. Yaiiez-Arancibia and D. Pauly (eds.) IOCIFAO
Workshop on Recruitment in Tropical Coastal Dernersal
Communities. IOCIFAO Workshop Rep. No. 44.
Supplement. 1988, 167-179.
23. Olanio V, Vergara M, Gonzales F. Assessment of the
Fisheries of Sorsogon Bay (Region 5), 2009, 5.
24. Pauly D, Navaluna NA. Monsoon-induced seasonality in
the recruitment of Philippine fishes, p. 823-833. In G.D.
Sharp and J. Csirke (eds.) Proceedings of the Expert
Consultation to Examine Changes in Abundance and
Species Compos~tion of Neritic Fish Resources. FA0
Fish. Rep. 1983; 3:291.
25. Pauly D. Fish population dynamics in tropical waters; a
manual for use with programmable calculators. ICLARM
Studies and Reviews 1984; 8:325.
26. Pauly D. Some definitions of overfishing relevant to
coastal zone management in Southeast Asia. Trop. Coast.
Area Manage. 1988; 3(1):14-15.
27. Philbrick CE. Length Frequency Analysis of Pelagic Fish
Species. Fishbyte, 1988 5.
28. Pollock B. Fisheries Management in the Philippines. A
brief overview. Paper contribution during the 2nd
National Fisheries Workshop. February 1996. Puerto
Azul, Cavite. 1996, 16.
29. Sphoer A. Change in Capture Fisheries. A Historical
Overview. Philippines Cultural Society, 1988, 25-26.
30. Surigaofocus.wordpress./hipada/
31. Tumanda MI. Jr. Panguil Bay: Change over time in
fisheries, In DA-. 2004, 326.