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Research Article
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Catch Composition of Estuarine Set Bag Net Fishery in the Coastal Area of Pontian, Johor, Peninsular Malaysia
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S.Y. Oh,
A. Arshad,
S.P. Pang
and
S.M. Nurul Amin
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ABSTRACT
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Catch composition of Estuarine Set Bag Net (ESBN) in coastal waters of Pontian, Johor, Peninsular Malaysia was investigated based on the catch data during June to November 2007. The total catches comprised of three major groups were Acetes shrimps (89%), juvenile fishes (9%) and other shrimps (2%). Among the Acetes shrimps, three species were recorded from the study area viz., Acetes indicus (74%), Acetes serrulatus (24%) and Acetes japonicus (2%). The nine juvenile fishes species were identified as Setipinna brevicep, Trichiurus lepturus (ribbon fish), Lutjanus malabaricus, Epinephelus diacanthus, Cynoglossus bilineatus, Secutor ruconius, Lactarius lactarius, Atelopus japonicus and Ilisha kampeni. Other shrimps were constituted of two families as Penaeidae (70%) and Thalassocaridae (30%). This study revealed that there is no bad impact of ESBN on juvenile fishes.
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INTRODUCTION
The genus Acetes forms the basis of small scale fisheries in south-east
Asia, Asia, Africa and South America and accounts for at least 13.5% of the
worlds total crustacean fisheries production, thereby comprising the largest
zooplankton based fishery in the world (Xiao and Greenwood,
1993). Fishing grounds are usually located in calm, muddy, near intertidal
zones where waters are shallower than 5 m (Omori, 1975).
Acetes swarms seasonally and fishing seasons usually coincide with swarming
seasons. The fishing gear is relatively simple and usually manually operated
and includes various kinds of push net (sungkor), bag net, stake-trap, beach
seine and small purse seine (Omori, 1975; Pathansali,
1966). The small size of the individuals is compensated by the great abundance
in which they are taken (Omori, 1975).
Both east and west coast of the Peninsular Malaysia are known to be very rich
in Acetes. The fishery is based mainly on A. indicus and A.
japonicus (Amin et al., 2009a, b;
Omori, 1975). Acetes erythraeus, A. serrulatus, A. sibogae
and A. vulgaris also occurred and is confined mainly to the west coast
from Perlis to Johor (Arshad et al., 2008; Johnson,
1976). In 2004 the annual catch in west coast of Johor exceeded 1,300 tons
and constitutes 17.41% of its total landing in Malaysia. Though small in the
amount annually landed, Acetes constitute a valuable and important seafood
commodity. Acetes are converted into a variety of preparations including
belacan, petis udang, sambal, trassi udang and chincalok. Surplus shrimps are
used in the preparation of animal or fish food, fed to poultry, or converted
into shrimps powder used as a fertilizer (Johnson, 1976).
Estuarine Set Bag Net (ESBN) has been using from decades but its catch composition
is still unknown so far. Despite great demand of Acetes in Malaysia,
the catch composition and status of this fishery is poorly known in Johor state,
Peninsular Malaysia. Although, some studies on population biology of the genus
Acetes have been reported (Amin et al., 2008a-c,
2009a-c; Arshad
et al., 2007, 2008), there have been no published
reports on the catch composition of Estuarine Set Bag Net (ESBN) fisheries in
Malaysia. Therefore, an attempt was made to study the catch composition of estuarine
set bag net in the coastal waters of Pontian, Johor Bahru, Peninsular Malaysia.
MATERIALS AND METHODS
Sampling method: Monthly samples were collected from the fisherman which
fished by Estuarine Set Bag Net (ESBN) from June to November 2007 in the coastal
area of Pontian (Lat. 0°16.13N°, Long. 103°28.34E°) Johor, Peninsular
of Malaysia (Fig. 1).
| Fig. 1: | Geographical
location of the sampling area ( )
in coast waters of Pontian, Johor, Peninsular Malaysia |
This gear is operated mostly within 10 m depth along the coast. The fishing
gear is 21 m in length and divided into three main parts which is mouth (mesh
size: 13 cm), middle (4 cm) and cod end (0.5 cm). Samples were preserved with
10% formalin immediately after collection.
Sample process: In the laboratory, 100 g of sub-samples were taken with three replicates from the original samples of each month. Then sub-samples were classified into three major groups like as Acetes shrimps, juvenile fishes and other shrimps.
Species identification: Identification for juvenile fishes and other
shrimps were done based on the study of Mokhsin and Ambak
(1996) and Lovett (1981). Acetes species was
identified under a dissecting microscope (Nikon-122764, Japan) according to
Omori (1975).
Data analysis: After that each separated groups were counted individually. Average percent composition of different groups was calculated from monthly sub sample data. Statistical software Excel was used for data analysis. RESULTS Catch category: There were three major groups of the species observed from the catches of ESBN in the coastal waters of Johor. The dominant group was Acetes shrimp (89%), followed by juvenile fishes (9%) and other shrimps (2%). Higher catches of Acetes shrimp were observed every month during the study period (Fig. 2). On the other hand, juvenile fishes and other shrimps only showed highest catch in the month of August and October (Fig. 2). Composition of Acetes shrimps: Three species of sergestid shrimps (Acetes indicus, Acetes serrulatus and Acetes japonicus) were found in coastal waters of Pontian, Johor (Table 1). The overall percentage composition of A. indicus, A. serrulatus and A. japonicus were found to be 74, 24 and 2%, respectively. Highest densities (more than 70%) of A. indicus were recorded almost all of the month (Fig. 3) in the investigated area. The occurrence of A. japonicus was only observed in November.
Composition of juvenile fishes: Nine species of juvenile fishes were
identified from the study area (Table 1). They were Septipinna
brevicep, Lutjanus malabaricus,Epinephelus diacanthus, Cynoglossus
bilineatus, Secutor ruconius, Lactarius lactarius, Atelopus
japonicus, Ilisha kampeni and Trichiurus lepturus. The species
Septipinna brevicep showed the highest number as a by catch in the ESBN
during the study period.
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Fig. 2: |
Monthly percentage variation in catch composition of ESBN
in the coastal water of Pontian, Johor, Malaysia |
| Fig. 3: | Monthly
variation in abundance of A. indicus, A. serrulatus and
A. japonicus in the coastal water of Pontian, Johor, Peninsular
Malaysia |
Table 1: | Monthly
catch composition (No. of individuals/100 g) in ESBN in the coastal water
of Pontian, Johor, Peninsular Malaysia |
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Highest number of juvenile fishes was observed in the month of August (Table
1).
Family Engraulididae (Septipinna brevicep) showed the highest number of by catch for juvenile fishes in the ESBN while family Trichiuridae (Trichiurus lepturus) showed the lowest occurrence compared to other families (Table 1). Composition of other shrimps: Other shrimps group comprised two families. The family Penaeidae constituted 70% compared to Thalassocaridae which contributed only 30% of the catch. DISCUSSION
Estuarine Set Bag Net (ESBN) is widely used to catch Acetes shrimps
in the coastal waters of Pontian, Johor, Peninsular Malaysia. Since this gear
is only used when tidal currents run, fishing is limited to the two periods
of spring tides of 7-8 days in every lunar month. According to the lunar calendar,
fishing days were from the 27th or 28th up to the 4th or 5th and from 12th or
13th to 21st or 22nd (Lam, 1975). In present study, Acetes
shrimps showed the highest constitution of the total catch with the highest
percentage (89%) while juvenile fishes (9%) and other shrimps (2%) contributed
very less. This is similar to the findings of Amin et
al. (2008a) in their study on catch per unit effort of estuarine push
net with emphasis on occurrence and abundance of Acetes shrimps in the
coastal waters of Malacca, Peninsular Malaysia, where Acetes shrimps
(90%) was the main catch followed by juvenile fishes (9%) and other shrimps
(1%). According to Khan et al. (1994), estuarine
push net production is less than bag net fishery, but the value of its catch
is higher than estuarine bag nets in Bangladesh. Chen et
al. (1997) reported the catch composition and seasonal variation of
set net fisheries in the Yellow and Bohai Seas. The catch composition comprised
the following: fish (54.4%), crustaceans (40.3%), cephalopoda (4.2%) and medusa
(1.1%). For crustaceans, A. chinensis constituted 40.6% of the total
fisheries yield in the region. Despite smaller mesh size (2 mm) used, the differences
in catch composition may be attributed to geographical variation.
In comparison to the push net, three species of Acetes shrimps (A.
indicus, 87%, A. japonicus, 12% and A. intermedius, 1%) were
recorded in the coastal waters of Malacca (Amin et al.,
2008a) which have very similar trend with the percentage composition of
Acetes in the present study are A. indicus (74%), A. serrulatus
(24%) and A. japonicas (2%). This study indicated that the estuarine
set bag net is an efficient fishing gear used by the coastal fishermen for the
harvesting of Acetes shrimps. Push net is the most common traditional
fishing gear employed in Acetes fishing in east coast of Peninsular Malaysia.
The catch efficiency of bag net and push net is similar despite the difference
in fishing operation and fishing area covered. It is important to note that
the cod ends of both nets are equal in size (0.5 cm). Both the traditional gears
have been shown to be equally efficient for capturing the Acetes resources
in the shallow coastal waters of Peninsular Malaysia. It could be concluded
that the ESBN is not posing any damaging effect to juvenile fishes in the investigated
area.
ACKNOWLEDGMENT This study was supported by the Ministry of Science, Technology and Innovation (MOSTI) with grant number 05-01-04-SF0613.
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