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Characteristics of an Exploited Tropical Shallow- Water Demersal Communltyln Malaysia

E.H.CHAN This study was designed to provide insights into the H.C.LIEW characteristics of an exploited community. It Faculty of and Marine Science had three major objectives: a) to provide information on Universiti Pertanian Malaysia the composition of the ; b) to determine the 43400 UfMSerdang food habits among the demersal ; and c) to Malaysia characterize the growth rates, exploitation rates and annual recruitment patterns for the common species.

':HAN, E.H. and H.C. LIEW. 1986. Characteristics of an exploited Materials and Methods tropical shallow-water demersal fish community in Malaysia, p. 349-3S2.1n 1.L. Maclean, L.B. Dizon and LV. Hosillos (eds.) The First Asian Fisheries Forum. Asian Fisheries Society, Manila, Data were obtained through a program Philippines. conducted WIthin 12 km off the coastline of Terengganu, Malaysia, where the depth of the water did not exceed 20 m (Fig. 1).•This area is suitable for trawling with respect to bottom characteristics (medium coarse to fine sand with Abstract some muddy patches) and is intensively exploited by small commercial trawlers and purse seiners below 40 gross tons Trawling provided insights into the characteristics of an exploited and by artisanal fishermen, tropical shallow-water demersal fish community. A total of 6,565 fish specimens weighing 285 kg were caught at 20 sampling stations. In all, Trawling was conducted using an otter trawl net with 139 species belonging to 50 families were recorded. The major families an effective wing-span of 6 m and a -end mesh size of ranked by weight were Dasyatidae (19.7%), (18.3%), 38.1 mm. Trawling was maintained for approximately 60 (8.9%), Dactylopteridae (8%), Nemipteridae (5.3%), min. at a tow speed of 2.3-2.4 knots. A total of 20 Lagocephalidae (5.2%), Priacanthidae (5%); and Mullidae (4%). The sampling stations were covered in six trawl operations overall fish trawled consisted of 53% food fish and 47% trash fish. The demersal fish community could be partitioned into four trophic groups, conducted between July 1984 and April 1985 (Table 1 and i.e., large zoobenthos feeders, intermediate predators, small demersal Fig. 1); Trawling was suspended during the northeast zoobenthos feeders and small demersal feeders. Small monsoon from November to March. played an important role as food resources for all the trophic Each haul was sorted to species and weighed. groups. They were the major food for small demersal zoobenthos feeders, Samples for stomach content analysis were immediately the dominant group, and large zoobenthos feeders. Analysis of growth preserved in 8% buffered formalin. Qualitative analysis of characteristics of ten common species using length-frequency data showed that Saurlda elongata and Trachlnocephalus myops the stomach contents for the species caught enabled them ·(Synodontidae) and Dactyloptena orlentalis (Daetylopteridae) had higher to be, partitioned into general feeding groups. growth rates than the other fishes in the community. Exploitation rates of Representative species from each group were also taken these three species by trawlers were also high although they have little for quantitative stomach content analysis using the commercial value. Annual recruitment patterns. for the demersal fishes gravimetric method. FOod groups in the stomachs were were generally protracted showing a single pulse, although some species have a second minor pulse. categorized as 1, intermediate predators; 2, ; 3, small demersal zoobenthos feeders; 4, small demersal zooplankton feeders; 5, heterotrophic (, Introduction cuttlefish and echinoderms); 6, large crustaceans; 7, small crustaceans; 'S, small molluscs and worms;' 9, The management of tropical multispecies fisheries ; and 10, zooplankton. has long been seen as a challenge to scientists. The Length-frequency data were also recorded for ten constraints are numerous and well-defined (pauly 1979; common .specles. ELEFAN I and ELEFAN II programs Marr 1982). Among some of the obvious constraints are described by Ingles and Pauly (1984) were used to lack of theory and databases. Larkin' (1982) outlined the estimate growth parameters (L .. and K), mortality (total requirements for research ranging from basic, data mortality, Z; mortality, F; and natural mortality, collection to development of theory applicable to M), exploitation rates (E), length at first capture (Le) and multispccies tropical fisheries. annual recruitment patterns.

349 350

Results and Discussion demersal zooplankton feeders (8.4%). large crustaceans (7.7%) and small crustaceans (4.3%). Pelagic fish. The trawl data are shown in Table 1. In all; 6.565 intermediate predators and heterotrophic benthos specimens weighing 285 kg were obtained. The overall contributed only minimally to the food items. percentage contribution of food fish (53% by weight) was The most important food group for small demersal comparable to that of trash fish (47% by weight). These zoobenthos feeders was small crustaceans which figures. although vastly different from values in one report contributed about 53.6% of the diet. followed by (Anon. 1967). do not differ much from figures given by heterotrophic benthos (15.4%). small molluscs and worms Pathansali et al. (1974), Jothy et al. (1975) and Lam et (11.5%). large crustaceans (9.9%) and small demersal al. (1975) from research trawl surveys conducted, in waters zooplankton feeders (5.7%). Small pelagic fish and small 10-20 m deep off the coast of Terengganu. However, the demersal zoobenthos feeders were found only in the percentage contribution of food fish may be grossly stomachs of Priacanthus tayenus and Nemipterus spp. overestimated since many of the food species caught were and played a minor role as a food group (Table 6). composed of small fish. Only three species of small demersal zooplankton Of the 139 species belonging to 50 families recorded. feeders were included for stomach content analysis (Table 75 were food fishes. The most abundant species by weight 7). These fed only on a small range of food groups. i.e.• were Dasyatis zugei (15.4%), Saurida elongata (10.2%). small crustaceans. small molluscs and worms and Dactyloptena orientalis (8%). Trachinocephalus .myops zooplankton. Daya jerdoni and Centriscus scuttatus fed (7.8%), Pseudorhombus javanicus (5.9%) and Priacanthus exclusively on zooplankton while Pentaprion longimana tayenus (5%) (Table 2). The families are listed by weight fed on small crustaceans and small molluscs and worms as in Table 3. well, but retaining zooplankton as the major food group. In a virgin stock before the introduction of trawling. The overall food compositionratios are shown in Table 7. Leiognatbidae and rays (Dasyatidae included) were the Many species showed trophic similarities suggesting two most abundant food fish families followed by a certain degree of competition on the same food groups. Tachysuridae, Carangidae,Nemipteridae and Competition for the same food groups occurred within the Pomadasyidae (Anon. 1967). Data from this study, which same feeding level as well as between different feeding reflect the effects of 18 years of trawling. show certain levels. Small crustaceans seem to play a major role as a deviations from the composition of a virgin 'stock. While food resource and were found in the stomachs of most of Dasyatidae still dominates in , Leiognathidae had the demersal fish present. They also constituted the major decreased significantly, presently contributing only 2.78% food group for small demersal zoobenthos feeders and of the total biomass. compared to 12.79% in a virgin stock. large zoobenthos feeders which made up 95% of the .total Pauly (1979) similarly found sharp declines in the biomass of the demersal fish 'present. The most abundant abundance of Leiognathidae as a result of trawling. Trash feeding group, i.e.. small demersal zoobenthos feeders fish families, Synodontidae, Paralichthyidae, contributed largely to the food of intermediate predators Dactylopteridae and LagocephaIidae seem to feature and would account for the relative abundance of the latter significantly in an intensively exploited stock while (45% of the total biomass). Hacunda (1981) similarly important food fish groups include Nemipteridae, found crustaceans to be the major prey group in all Priacanthidae, Mullidae and Carangidae. demersal predators present in a coastal area of the Gulf of Qualitative stomach content analysis showed that the and concluded that predators rely on the same demersal species could be conveniently grouped into four major food sources. He also provided data to show that feeding levels. These were large zoobenthos feeders (6 trophic partitioning by prey size occurred-and this would species). intermediate predators (29 species). small help reduce intense competition on similar food groups. demersal zoobenthos feeders (81 species) and small Differences in daily, seasonal and spatial patterns of demersal zooplankton feeders (8 species). - feeding could provide another means of reducing Food composition da-ta for large zoobenthos feeders interspecific competition. Keast (1973) found that food were obtained for three species. i.e., Dasyatis uarnak, D. overlap occurs when a particular food resource becomes zugei and Drepane punctata (Table 4). Small crustaceans superabundant. This could be the case for small featured as the major food group. making 66.4% of the crustaceans in the shallow-water habitats off Terengganu. diet by weight, followed by large crustaceans (26.3%). A summary of the growth parameters. mortality small molluscs and worms (7%) and heterotrophic' benthos rates, exploitation rates and.annual recruitment patterns of (0.3%). 10 common species caught are given in Table 8. Higher The food groups of intermediate predators are shown growth rates, as indicated by the growth coefficient, k, in Table 5. Small demersal zoobenthos feeders constituted were observed in Sauridaelongata. Trachinocephalus the most important food group (76.5%) followed by small myops, Dactyloptena orientalis and Gastrophysus 351 scleratus than' in Priacanthus tayenus, Leiognathus Marr, I.C. 1982. The realities oC fishery management in the Southeast elongatus and Daya jerdoni. Exploitation rates were also Asian Region, p. 299-307. In D. Pauly and Gl. Murphy (eds.) high for Saurida elongata, Trachnicephalus myops and Theory and management oC tropical fisheries. ICLAR..\1 Cone. Dactyloptena orientalis although these fishes have little Proc. 9. 360 p. International Center Cor Living Aquatic Resources Management, Manila, Philippines and Division of FISheries commercial value. Annual recruitment patterns for the Research, Commonwealth Scientific and Industrial Research demersal fishes analyzed are shown in Fig. 2. Recruitment Organisation, Cronulla, Australia. patterns were generally protracted, showing a single pulse Pathasali, D., G. Rauck, A.A. Iothy, M.S.B.S.A. LatifC and T.B. Custin. as in Upeneus sulphureus, Gastrophysus scleratus, 1974. Demersal fish resources in Malaysian waters. (Trawl survey Saurida elongata, Trachinocephalus myops and oC the coastal waters ofC the east coast oC West Malaysia). Fish. ijull. Minist, Agric. Fish. Malays. 1. Pseudorhombus javanicus. However, Pentaprion Pauly, D. 1979. Theory and management of tropical multispecies stocks: longimana had a second pulse, similar to that reported by a review with emphasis on the Southeast Asian demersal fisheries. Ingles and Pauly (1984) for this species in the Philippines. ICLARM Stud, Rev. 1. 3S p. International Center for Living Aquatic Resources Management, Manila, Philippines.

Acknowledgements Palau This srudy was supported by the 'Intemational Development CD CJ Bldong Research Centre oC Canada. The authors are indebted to Dr. Daniel Lout Pauly, ICLARM, Cor his invaluable help. Technical assistance was provided by En. Mohamad Muda, En. Johari Md. Noor and En. Muhammad Embong. Assoc. ProC. Mohd. Ibrahim Hj. Mohamed, former dean, Faculty oC Fisheries and' Marine Science, UPM, is also South China acknowledged Corhis kind encouragement. 30'

References

Anon. 1967. Results oCthe joint Thai-Malaysian-German trawling survey oC the east coast oC the Malay Peninsula, 1967. Marine Fisheries Laboratory, Department of Fisheries, Ministry of Agricultun;; Bangkok, Thailand and the Fisheries Research Institute, FISheries Division. Ministry of Agriculture and Cooperatives, Malaysia. Hacunda, I.S. 1981. Trophic relationships among demersal fishes in a coastal area oCthe Gulf oCMaine. Fish. Bull. 79(4):775-788. o 5 Ingles, I. and D. Pauly. i984. An atlas oC growth, mortality and km recruitment of Philippine fishes. ICLARM Tech. Rep. 13. 127 p. Institute of Fisheries Deveopment and Research, College of Fisheries, University of the Philippines in the Visayas, Quezon Palau 5'15'N City and International Center Cor Living Aquatic Resources and Kapal Management, Manila, Philippines. 4~ Jothy, A.A., G. Rauck, M.S.B.S.A. LatifC, K.S. Ong, P.C. Uong and 1.L. Carvalho. 1975. Demersal fish resources in Malaysian waters. 3. 103'E 10' 15' Second trawl survey oC the coastal waters oCC the east coast oC Fig. 1. StudY area showing the location of sam~ling stations. Peninsular Malaysia (March-May 1977). Fish. Bull. Minist, Agric. Rum Dev., Malays. 4. Keast, A. 1973. Cood specializations and bio-energetics interrelations in the fish oC some small Ontario waterways, p. 377-414.ln I.H. Steele (ed.) Marine Cood chains. Oliver and Boyd, Edinburgh. Lam, W.C., W. Weber, A.K. Lee, K.S. Ong and P.C. Liong. 1975. Demersal fisl) resources in Malaysian waters. 7. Third east-coast trawl survey 'oCC the east coast of, Peninsular Malaysia. (14th August-20th September 1972). Fish. Bull. Mlnist, Agric. Rural Dev. Malays. 9. Larkin, P.A. 1982. Directions Corfuture research in tropical multi species fisheries, p. 309-318.ln D. Pauly and O.L Murphy (cds.) Theory and management oCtropical fisheries. ICLARM Conf. Proc. 9. 360 p. . International Center Cor Uving Aquatic Resources Management, Manila, Philippines and Division oC Fisheries Research, Commonwealth Scientific and Industrihl Research Organisation, Cronulla, Australia. Fig. 2.~ Annual recruitment patterns for common demersal fish. 352

T,bl • .c. Food compos.lic.n fo, 1"11. ,oob.nII'lOI feed.,.. S••••• , fo' foOd g'oup d.siVnal;on,. TtIb6e 1. S-.v.' "....1cM'., T.""W"",, ...... , .... J~'Il ... ·...p". 1185. ,,,;0' ... Togl.,., .....g. loobenthos Food group, W.igh, (kg) R.I.ti"". .... _ of 11th To,'" flO, 'ood I•.,. T,.", 101ft t.eder, 6 7 caught ".C't;On _ '!Ioby wt. "'by N). ""by ""I • .... It' O"IIh '''yl'lO.

., 57 o.•.,..tj, u.,,..1t 0 0 .88 .,2 2.9'0 .058 OJ n.D7 •• :r.nl '0' ., 02 22D7'.14 a.1l1 130 .," ., 5' D.,.,..,i"u'_; 0 .30 .70 0 43.900 .876 , 17 •• ,. OJ ".ca", "...,. .. ., Dllp.n. punet.t. .05 0 0 .95 3.3,5 .065 ... ".QI.&4 22_ "46 " sa 01 23"0.' 'Ul,._ """It, " .. .&64 .070 ,...... , 0.".... 11"'0 .003 .263 01 2).01" .. OJ ao• la• 80 ,. 2,.01'" 11.13' 01 23J)1 .... '.1'0 ,at"" 30 50 '0 .. 01 t7111 ... ',101 ,,. , , til 88 10 n..... ".131 .. '5 12 II TIb .. 5. FOOd c:onwmpclOft 'Mio, 10, .,.,wmediM. ptect.to". See' •• ~to, rood l'OuP IMlig"MioM. 17De .... '1,731· COl ,. ,. ., '" .. tft,.,med ... Fooct.,oupa A.tMiwe " 17.08 .... '2 .... ,.. ,. ,. ,. a5 W',,"'(kil ,.. . 1 tractlO" " 22.10 .... ' ,.. .. ., .. ~ed.ltOf' ! ;' .• . _-, ,. 21 "14 22.10 ...... 1.1'0 .2 ., , II .,,,U, ".463 II ., 12 .," 'J. ,. 07.04. 2n. '22 14 20 II 80• S.lIrIcM .""".,. 0 0 .... .'ao .2>4 25.33 .304 .,..... 14,707 '01 12 .. • ~momlMI' 'PP . 0 0 ... JIll 0 .112 23.11 " ., TIKhittoc~. MyofM 0 JI89 0 0 21 .• 1 .. " 074'.85 • .111 25' "12 .. ,... '0 .... 'I .,..... '.788 ... 12 ,. .. " Aliu,m...,inw 0 0 .'00 0 "" .'00 ~OO 4.17 .1160 1pIt"_.,,._. 0 0 3.13 ",2 ao'. 07.04.aa n,'''' .,. .. ,. 22 .'00 .... .200 ~OO Lu~ftU'lPP. 0 0 .12' .... .11' .001 0 2.'7 T...... IN.,..- 13 .' -.n-47 """04 .. .,."". 0 0 .700 .300 0 0 "., ,," 214'" $NI. tmdo.,.,_, 0 0 .130 0 .3. --.. --.. ~.. 0'°30; .... 'iltuI.,. 'PP. 0 0 0 I_ 0 .11 -D02 Ow,.U,.toO ...... , .,.. ".. .ooe ...., T.bl. 2. Maio' lPKin caught by d.-nersal """,I, listed in dISC,nding OrcHrby w.igh~. ""

Spec," hmily Weight CD' "by wt.

Ouy.rilz .. i OalVltid .. 43,900 15.41 $MI," oIonllOlIJ S.,nadon1oM 28.942 10.16 8.03 o.ctyloprMII ",i.,.r./il DlctvIOP,"id .. 22.B90 ew,.."...,..,..,.wll • .,.. ... 0 • II.H ~.. TtadtinouphMfII myopl Svnoden1"'. 22.J43 7.B4 DO' • " .n. .0lD 0 'JQ l1li' "*-t-''''''''''' .'" •0 ...,.. ., lO..2J fJWudotltombul ~~.nicUl Paralichthyid .. 16,820 5.90 • . • • .'lI ,....,." .... .10t •~II .... .361 .0'13 0 , .,ao Pri«MJtltul gyMUI PriKanthidal 14,358 5.04 • • .. • 0 .. O· .... .127 GMtrophy_ICI.,. .... Ugoc"' ... ., .. 8.724 3.41 • . • • • DU --.... • 0 800 0 I.•' ' """'_. .-.... -O,_..,..,..",,_...... • • • • •0 Out.rillP. o.,yatid .. 8.000 3.16 '.000 ,.. • • •.112. • •.201' •.110 • ,... .031 Mullid .. 6.BB7 2.42 ~ ...... ~""p/NI_' • • • .200 • • U, Ariid .. 4,970 1.75 • • • • • • •.200 - ..,... 0 'DO "".0" 1.&2 • • • • • • , .1121 0..,.j.tdo";_- Pomac.ntrid .. 4.822 JitMw'--.... 0 .'00 -.200 ... ~OO .. • •JI43 • • ~id .. trNI.,.,icuI CorM9- 4,278 1.50 GM.,....,. 0 • • • .-'oa DI' • • u• "". 1.02 -- t...... rhu' ,~rlll L.iOtNlhidH 4.038 0...... ,... D14 D" DI' ,.. .u, ...... ParalichihyidH 4.038 1.42 ." -$coIopIiI lNftiopr"", Ntmip",id .. 3.800 1.33 - - GOIfrophy_IPMI.... /I 3.600 1.26 ~c"",""" Tebl. 7, Food conlUmptton ,.. tos '0' ""aU d.mtrsaf zoopllnk,on f.teler •. See •• xt fo, food Group lH"",,'PUlICgEl Dr_c .. 3,315 1.1~ G)o'mIIIIX"niu, ,,*cI1 ,,",.,odd .. 3.135 1.10 d·'19Ntionl. Splry- .... SphyrHnid. 3.100 1.09 R,ll1ive Our.';' UMttM Daly'tidH 2,910 1.()2 Sm.nd"" .... ' Food groups Weight Ikg! zoopllnktOn feeder, 8 10 AUght frKtton

t .... , .•• ._ ..... IN ___ II.... 1.1d _rei"". P.",.p,ion long;",.,.. .18 .20 .62 1.61 .308 CM.,.. ;'rdoni 0 0 1.00 3.29 .628 C.nrtisl;u, ICUrt.hi, 0 0 1.00 .33 .063 --..-... W..-I,,' .by_"" ev....11IItio .055 .062 .883 14.,.,0 '1.7'1 Iy...,.,.. ... 12.0. 11..2. ---,,-,ou..,idM a.4l1 ....._ '\~h Deely...... 22.... Tabl, 8. Growth, monllity and .. .,loitl1iOn .,It.,n.tt" for 10 common detnl, ...lspecIH. N_ ..... 1II8It 11- 1,2', ..._- 14))1 1.171 _ ...... , Species ~Icml K Z lA E LcJcml ...,.1...... , c..... _ It.'" 2.710 7.1"""" 2."" AtiidM ..... 1.470 U" l'enr.prion Iong;m.". 16.0 1.1 3.8 2.3 1.5 0.4 8.7 --- I.J13 ...... '.DU (J«tylop,.,.. ori.,.t";, 23.Q 1.5 10.6 2.5 8.1 0.8 12.5 ,- '.IU ...... U".MU' IUlphunu, 23.0 1.1 5.0 2.1 2.3 0.6 11.0 L~ ... ., - U>4 ... 40 O• ..,.jlrdOili 17.0 0.8 3.1 1.8 1.3 0.4 5.6 .- U13 U,. L,iog,..rhw "~hI' 13.S OB 2.4 1.8 0.5 0.2 8.2 un '~30 P,iK."rhu, r• .,..,..,. 27.0 0.8 2.9 1.3 1.8 0.6 13.0 -- 1,'17 1.1" -- ,,,,. 'DU GMttOphrlUl x/.,.tu, 18.0 1.5 4.2 2.7 1.5 0.4 10.9 "-'III~"" '-- IN> SMI,Id. • 370 1.8 7.& 0.7 21.D 0 .. ' "on,.,. '.3 5.' -- 1..1U 0'" TtKhiftOC~.,u. m.,.op. 36.5 1.8 8.0 2.3 5.7 0.7 17.• o.-... __ 0."2 -- '.20' Puudorltombu, j.lI.nicu. 26.5 1.2 2.0 2.1 0.3 0.1 21.1 - 0.711 '- 'P21 OAll' c...... ,-,"', 0..., -- I.DJ, O.3JJ T,....".,."'idM "'''0 0.171 --- '42 0>00 L.. ""-.... no 0.... --...... ,. 0,21' _ ... 0.'" NI 0.1" Cy,..lO..ue ... 0.'" a.,.,0__ ... eo._ ... 0.'4' -- ,.. 0.'12 c:-. .. _ ... 0.12' ,.. 0.1'. T.. ,_"' .... 220 0.111 .... HI T_- ... ODO' •• ...a.o ...... -... T,,__ ," .0 ...... ,.. OD" _- "... 0.017 ....._IY'*'C" ...... o.o'J .. 0.0'1 - Cl ODII ...... 0_ II T'--..... ,. .-..., -Tow ...... '