.JJlIIJl'I'AN1)IUU.lJlNAN DEPARTMENT OF FISHERIES. 1)ll(}SII)INey SI~)IIN1\ll. 1))~NflnJlnl{llN 1)1~IUI{l\Nl\N. I!)f)I ISBN:

Transcription

1 .JJlIIJl'I'AN1)IUU.lJlNAN DEPARTMENT OF FISHERIES 1)ll(}SII)INey SI~)IIN1\ll 1))~NflnJlnl{llN 1)1~IUI{l\Nl\N I!)f)I ISBN: I INSTITUT PENYELIDIKAN PERIKANAN (Fisheries Research Institute) GELUGOR, PULAU PINANG Tel: Fax:

2 THE MAXIMUM SUSTAINABLE YIELD OF THE DEMERSAL FISHERY OF THE WEST COAST OF PENINSULAR MALAYSIA AND ITS USE IN MANAGING THE FISHERY Chee Phaik Ean Fisheries Research Institute Gelugor, Penang. An assessment of the inshore demersal fishery of the west coast of Peninsular Malaysia was undertaken using the annual catch rates recorded by the research vessel as indices of abundance. The fishing effort exerted on the west coast inshore demersal fishery was standardised to the number of research trawl hours. The maximum sustainable yield or MSY as determined from this analysis using Schaefer's production model, was 181,500 tonnes. The fishing effort at MSY was 2,382,000 research trawl hours. The results obtained from this analysis show that the inshore demersal fishery on the west coast of Peninsular is over-exploited and a reduction in fishing effort is urgently required. Sumber perikanan demersal laut pantai di pantai barat Semenanjung Malaysia telah ditaksirkan dengan menggunakan kadar tangkapan yang telah diperolehi oleh kapal penyelidikan sebagai petunjuk banyaknya sumber. Daya usaha menangkap ikan untuk perikanan demersallaut pantai telah dipiawaikan kepada bilangan jam menunda oleh kapal penyelidikan. Hasil berkekalan maksimum atau MSY yang ditentukan dengan menggunakan model pengeluaran Schaefer ialah 181,500 tan metrik. Daya usaha menangkap ikan pada tahap MSY ialah 2,382,000 jam menunda oleh kapal penyelidikan. Keputusan daripada analisis ini menunjukkan bahawa perikanan demersallaut pantai di pantai barat Semenanjung Malaysia telah d't k" I ero al dengan berleblhan dan pengurangan daya usaha menangkap.. Ikan amat dl- P6rlukan. Since the introduction of the trawl to the west coast of Peninsular Malaysia, the demersal fishery has!cfevelopedat a r'd ' 1\1I._ api rate. ThiS has caused serious problems in the management of this fishery. As with vu..,r expand', 109 fl~heries, the early entrants benefited from the profits made. This attracted more

3 entrants until the returns turned to be much less profitable. While the early entrants profited, the late entrants, having invested large capital sums, find it hard to exit from the fishery. This will lead to overinvestment and over-capitalisation of an open-access fishery if left uncontrolled. A comprehensive review of the development of the fisheries on the west coast of Peninsular Malaysia is given in Yap (1976). Presently the trawl remains one of the two commercial (as opposed to the traditional) fishing gears in Malaysia. The trawl is the major gear for catching demersal fish while the purse seine catches the bulk of the pelagic species. The main target species of the trawlers are prawns. However the trawl presently in use, with one-inch cod-end meshes, is not selective. A large variety of fish species are usually caught together. These also include the young, immature and under-sized individuals of many commercial species which are notmarketable as food fish, thus they are sold as trash together with the genuine trash fish species. The high proportion oftrash fish in the landings of the trawlers together with the disappearance of certain commercial species e.g. Lactarius /actarius and Hi/sa from the inshore fisheries on the west coast of Peninsular Malaysia calls for urgent management measures to be implemented. It has been realised that management measures must be implemented early development of any fishery, but in most cases the pace of development of the fishing industry Ii much faster than the rate at which research data can be accumulated for detailed assessme to be made. In the tropics, the mixed nature of the fisheries and the multitude of species caught in one fish!

4 A series of monitoring surveys using the bottom trawl for demersal fish had been conducted by the these surveys w f' ' ere Itted to the surplus production model of Schaefer (1954) to determine the MSY. 'ng effort Usedwas estimated by dividing the total demersal fish landed (Annual Fisheries Statistics,

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6 the present analysis of the MSY uses the catch rates obtained by the research vessel as a measure Of~e index of ab d un ance of demersal fish. The number of trawl hours exerted by the research vessel was to standardise th f. e Ishlng effort. An attempt to standardise the fishing effort by using research trawl }Vas made by Lu' let at. (1983). The procedure used in standardising fishing effort here may be less \de at~use of the I. arge vanety of gear used in the Malaysian demersal fishery.

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8 Weaknesses of MSY as an objective for managing the west coast demersal fishery The use of the maximum sustainable yield as an aim for fisheries management has been heavily criticised (Larkin, 1977). The concept of MSY is too simple. This has led to the use of maximum economic yield, MEV, which attempts to account for the economics of the fishing operations. This could be useful for management. " Since the fishing effort estimated at MEY is below that estimated at MSY. However MEY is.etiuinsufficient.. since the social aspects of the target groups have also to be considered. Thus the maximum

9 not been used for the management of the complex tropical species where many predator-prey relationships have not been fully understood. In addition to these, ecosystems models (Laevastu and Larkins, 1981

10 for the west coast demersal fishery of Peninsular Malaysia, strict entry into this fishery has to be enforced. This had been recommended much earlier on (Lui et al., 1983). A reduction in fishing effort, OUgh a reduction in the number of licences of fishing boats or gear, could result in an increase in yield. the lame am t h. oun t at could be harvested, the cost of fishing could also be reduced. The landings of I fish from an effort of about 2,900,000 research trawl hours were close to 170,000 tonnes in 1980 ). A similar qu. antum of yield could be achieved with just less than 2,500,000 research trawl

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12 Beverton, R.J.H. and S.J. Holt On the dynamics of unexploited fish population. Fish. Invest. Minist. Agric. Fish. Food UK (series 2), No. 19: 533 p. Fox, W.W An exponential surplus-yield model for optimising exploited fish populations. Trans. Am. Fish. Soc. 99 (1): James, M.K. and K.P. Stark Application of the Three Bays ecosystem model to fisheries management. In: Pauly, D. and G.1. Murphy (eds.) Theory and management of tropical fisheries. ICLARM Conference Proceedings 9, 360 p. International Centre for Living Aquatic Resources Management, Manila, Philippines and Division of Fisheries Research, Commonwealth Scientific and Industrial Research Organisation, Cronulla, Australia. Laevastu, T. and H.A. Larkins Marine Fishery Ecosystem. Its Quantitative Evaluation and Management. Fishing News Books, England, 162 p. Larkin, P.A An epitaph for the concept of maximum sustainable yield. Trans. Am. Fish. Soc. 106(1): LUi,V.P., P.E. Chee and E. Savariraj Ulangkaji dan analisa terhadap keadaan sumber perikanan di perairan Semenanjung Malaysia. Report prepared for the Department of Fisheries, Malaysia. Mohd. Shaari bin Sam Abdul Latiff Demersal fish resources surveys and problems of fisheries management. In: Fisheries Bulletin No. 15, Ministry of Agriculture, Malaysia. Pathansali. D Some observations on catch and effort of commercial and research trawlers with estimates of yield. In:Tiews, K. (ed.) Fisheries Resources and their Management in Southeast Asia. Druckerei Heinz Lammerich, Bonn, Federal Republic of Germany, Polovina J J An overview of the ECOPATH model. Fishbyte 2(2): 5-7. POPe,J.G Stock assessment in multispecies fisheries. South China Sea Fisheries Development and Coor~inating Programme SCS/DEV/79/19. FAO, Manila, Philippines. I P.M Optimum sustainable yield as a concept in fisheries management. American SOCietySp. I '. ecla Publication 9. Fisheries

13 Schaefer, M.B Some aspects of the dynamics of populations important to the management of marine fisheries. Bull. IATTC, NO.1: Sparre, P. and R. Willmann Bioeconomic Analytical Model for Tropical Fisheries (A simulation model implemented for microcomputers). Fisheries Department, FAO (Unpublished), 155 p. Willmann, R. and S.M. Garcia A bio-economic model for the analysis of sequential artisanal and industrial fisheries for tropical shrimp (With a case study of Suriname shrimp fisheries). FAO Fisheries Technical Paper 270, FAO, Rome, Italy. Yap, C.L Fishery policies and development with special reference to the west coast of Peninsular Malaysia from the early 1900's. In: Fredericks, L.J. (ed.) Proceedings of the Seminar on the Development of the Fisheries Sector in Malaysia Kajian Ekonomi Malaysia Vol. XIII Nos. 1 & 2, 7-16.

14 marine Table 1: Annual catch rates recorded by the research vessel nmodel Year Total demersal Catch rates Estimated fishing fish landings (kg / hr) effort (tonnes) (no. trawl hours) anal and 3S). FAO , , , , , ,629, 'eninsular 1ar on the -.los.1 & 2, , ,605, , ,866, , ,156, , ,433, Table 2: MSY and Fishing effort estimated for the demersal fishery of the west coa,st of Peninsular Malaysia Table 3: Estimates of the potential for the inshore demersal fishery of the west coast of Peninsular Malaysia Types of resource Estimated potential Source Tonnes Demersal fish 105,000 Pathansali 1976 Prawns 38,000 Pathansali 1976 Demersal fish & prawns 62,000 Mohd. Shaari 1976 Demersal fish 199,000 Lui et al Prawns 55,000 Lui et al. 1983

15 Table 4: The estimated number of trawlers in operation for the years the research vessel conducted surveys Year No. of trawlers Estimated effort in no. of in operation* research trawl hours , , , , , , , * Total number estimated including the effort exerted by other gears that catch demersal fish converted to units of trawlers Table 5: Percentage Malaysia of trash fish in the total demersal fish landings on the west coast of Peninsular Year 0/

16 j ~o 130 '" 120 '" "III r" c~ CC '" 100 '-/:3 v O 90 -~.!!t >- BO ~O 30' 20 fish 10 nsular 0 Fig. 1: Yield from the inshore demersal fishery of the west coast of Peninsular Malaysia. shows the observed landings of demersal fish for the given year ~.5 Research trawlhours (X 1.000,000) Fig. 2: Inshore demersal fishery landings of the west coast of Peninsular Malaysia. Year 81