catch composition for main marine shrimp species in bangladesh

BANGLADESH RESEARCH PUBLICATIONS JOURNALISSN: 1998-2003, Volume: 7, Issue: 2, Page: 91-98, July – August, 2012CATCH COMPOSITION FOR MAIN MARINE SHRIMP SPECIES INBANGLADESHM. S. Uddin 1 , E. Karim 2 *, S. J. Hasan 3 , S. Barua 4 and N. M. Humayun 5M. S. Uddin, E. Karim, S. J. Hasan, S. Barua and N. M. Humayun (2012). Catch Composition for MainMarine Shrimp Species in Bangladesh. Bangladesh Res. Pub. J. 7(2): 91-98. Retrieve fromhttp://www.bdresearchpublications.com/admin/journal/upload/09319/09319.pdfAbstractYearly total catch and trends of catch composition for major marineshrimp species were evaluated from the landing data by the commercialshrimp trawlers fishing in the four major fishing grounds within the exclusiveeconomic zone (EEZ) of Bangladesh. Data set were collected from thelandings for the year of 1986-87 to 2010-11 and were calculated totalcatch, catch per unit effort (CPUE), and percent and tendency of catchcomposition and amount of finfish as bycatch accordingly. Total numbersof shrimp trawler engaged in shrimp catch and finfish as bycatch werevaried from 31 to 48 and also fishing days fluctuate from 4581 to 7866. Thetotal shrimp catch fluctuate from 2138 to 4830 MT for the year of 2006-07and 1988-89, respectively and finfish bycatch fluctuate from 1836 to 6157MT. The contribution of brown shrimp was highest for entire time period andvaries from 53-72% of the total catch. On the other hand white shrimpcontributes lowest portion (1-13%) of the total catch. The CPUE for tigershrimp, brown shrimp and Indian white shrimp were varied from 23-89, 191-465 and 7-65 kg d-1, respectively. The highest CPUE with 465 kg d-1 (65.4%of the total catch) was observed in the year of 1990-91 by the contributionof the brown shrimp. The percent contribution of tiger shrimp wasdecreased slowly but increased in case of brown shrimp and for Indianwhite shrimp the contribution was stable. The trends of total shrimp and fishcatch were decreased from the beginning to the end of time period.Keywords: CPUE (Catch per unit effort), tiger shrimp (Penaeus monodon), EEZ(Exclusive economic zone)IntroductionThe fishery sector in Bangladesh plays a vital role in meeting 58% of theprotein demand, employment opportunity and 2.7% of the total export earningsof the country. Within total 2.5 million MT fish production marine catch contributes21% in Bangladesh (DoF, 2011). Countries fish production is increasing day by bayfrom both in aquaculture and marine sector. At the onset of the development forthe marine sector several researches were undertaken supported by differentdonors including FAO. Two research vessels were in possession of the Departmentof Fisheries and utilized for researches during 1981 to 1988 and continued up to1997 with some limited manner. Limited information about the intensity of fishingpressure and the status of exploitation rate of the coastal resources of Bangladeshis available (Mustafa 1994; Mustafa 1999; Mustafa and Khan 1993; Mustafa et al.1996). However, several resource surveys have been carried out in Bangladeshmarine waters and these reported that the fisheries resources were still abundant(Khan et al. 1989; Lamboeuf 1987; Mustafa and Khan 1993; Mustafa et al. 1996).*Corresponding author: ehsan_tony@yahoo.com1. Senior Upazilla Fisheries Officer, Teknaf, DoF; 2. Scientific Officer, MFTS, BFRI; 3. Scientific Officer, RS,BFRI; 4. Statistical Officer, Marine Unit, DoF; 5. Director, Marine Unit, DoF

Uddin et al.Almost 43000 of artisanal mechanized and non-mechanized boats and 154industrial fishing trawlers are engaged to fish in the exclusively economic zone(EEZ) of the Bay of Bengal in Bangladesh (DoF, 2010). Though the artisanal sectorcontributes 91% of the marine catch, but the landings don’t occur in a managedway due to lack of sufficient fish landing centre in the coastal part of the country.On the other hand fish landing by industrial fishing trawlers are operated with asystematic manner under the close supervision by Marine Fisheries Office,Chittagong. The present statuses of the fishing pressure on the marine resourcesneed to be analyzed for proper management. There is scope to find out thetrends of fish availability and stock position by analyzing contribution of mainspecies to the total catch and catch per unit effort (CPUE) with the collectedcatch data by the Skippers upon arrival from their sea voyages.A multi-species, multi-gear fishery exploits the traditional fishing grounds inBangladesh waters. No management decision can be ideally taken on the basisof these surveys any more. New surveys and new information of marine stocks arerequired for proper management strategy. The present study looked at thecomposition of shrimp species assemblages based on the commercial industrialtrawler catch. Specifically the study aimed to describe the composition of thespecies assemblages. The tendency of the marine shrimp stock might becalculated by analyzing with that secondary data accordingly. This paperproposes the tendency of the marine shrimp stock in the country’s EEZ to providea salient feature of the available information and resource base managementplan and to identify future research.Materials and methodsThere are four major fishing grounds (Figure-1) in the exclusive economic zone(EEZ) of Bangladesh (i.e. South Patches, South of South Patches, Middling andSwatch of No Ground). Now 35 shrimp and 119 fish trawlers are engaged in fishingwithin these grounds. As expected, catch composition from shrimp trawlsconsisted mainly of shrimp species. The main target species of this analysis weretiger shrimp (Penaeus monodon), Indian white shrimp (P. indicus), brown shrimps(Metapenaeus monoceros, M. Brevicornis, M. spinulatus) and mixed of other lesscommercial species (Parapeneopsis sculptilis, P. Stylifera, Acetus indicus).92Figure 1. Fishing grounds in the Bay of Bengal, Bangladesh (Source: SatteliteImage-Marine Fisheries Surveillance & Management Unit, Chittagong).http://www.bdresearchpublications.com/journal/

Catch Composition for Main Marine Shrimp SpeciesShrimp trawlers engaged in fishing in the EEZ of Bangladesh having a capacity ofgross tonnage 150-250 MT with main engine power 500-900 BHP. These vesselsusually sail for 30 days time period per voyage and every day complete 5-6 haulsfor a period of 3-4 hours. But the fishing days and number of hauling fully dependsupon weather and sea worthiness and functioning of the fishing vessel itself.However the most the fishing days vary from 20-25 days per trip per vessel, thoughsometimes it comes to only 3-5 days. A common log sheet has been provided tothe trawler owners or company for reporting of their trawl catch prior to get asailing permission for the upcoming fishing trip. Skippers of these fishing vessels fillthe supplied log sheet after each haul accordingly. Secondary shrimp landingdata from this log sheet are available by the shrimp trawlers that have beensubmitted to the Marine Fisheries Office. Cross checking of these landinginformation are generally done by the authorized person on random basis duringlandings of the catch.The catch of fish, in numbers or in weight, taken by a defined unit of fishingeffort is catch per unit effort (CPUE). Large CPUEs indicate large populations sincemany individuals are caught for every unit of fishing effort. CPUE standardizescatch data based on the amount of the effort (total time or area sampled)exerted. Also called; catch per effort, fishing success, availability. Ex: tons ofshrimp per tow or day, pounds of fish per hundred longline hooks. CPUE is ameasure of the density or population size of an animal that is targeted by fishing.Because sampling effort may differ from area to area, month to month, or year toyear; the number of fish captured must be analyzed in such a way as tostandardize the effort that was exerted. Considering the scope an effort wasdone to find out the trends of shrimp availability and trend of stock position byanalyzing species wise total catch, contribution of individual species to the totalcatch and CPUE with the data from the fishing log sheet submitted in MarineFisheries Office by the Skippers upon arrival from their sea voyages.Input data were catch weights, fishing days and number of trawlers fromshrimp trawl landings, i.e. total shrimp catch, total fish as bycatch, and individualcatch of main shrimp species from the last 25 years (1986-87 to 2010-11) catch.Since expressing abundance on relatively crude scales retains much of thequantitative information. In this article CPUE was calculated on daily basis fishing,i.e. how much (in weight) fish were caught by one vessel per day. For thestatistical analysis of that data Microsoft excel was used for calculating relativeabundance of major shrimp stocks and trends of the composition of the shrimpand fish in the EEZ of Bangladesh.ResultsTotal numbers of shrimp trawler engaged in shrimp catch and finfish asbycatch were varied from 31 to 48 and also fishing days fluctuate from 4581 to7866 (Table-1). The highest and lowest numbers of shrimp trawler were engaged infishing in the year of 1997-98 and 1986-87, respectively. The total shrimp catchfluctuate from 2138 to 4830 MT for the year of 2006-07 and 1988-89, respectivelyand finfish bycatch fluctuate from 1836 to 6157 MT. The trends of total shrimp andfish catch were decreased from the beginning to the end of time period (Figure-2).93http://www.bdresearchpublications.com/journal/

Uddin et al.Table 1. Numbers of shrimp trawlers were engaged and fishing days for the yearof 1986-87 to 2010-11(Source: BMFSMU, DoF )Year No of trawlers Fishing days Year No of trawlers Fishing days1986-87 31 6429 1999-00 44 71521987-88 33 6642 2000-01 44 72891988-89 42 7806 2001-02 44 69351989-90 44 7394 2002-03 45 70691990-91 42 5658 2003-04 45 74421991-92 46 5529 2004-05 45 78661992-93 37 6588 2005-06 41 74661993-94 40 7113 2006-07 39 59191994-95 43 6691 2007-08 38 59691995-96 41 6502 2008-09 40 59561996-97 41 6914 2009-10 41 45811997-98 48 7044 2010-11 40 47181998-99 41 764594Figure 2. Total shrimp and fish catch by shrimp trawlers and trends of shrimp andfish stock in the Bay of Bengal, Bangladesh (Source: BMFSMU, DoF )The key commercial marine shrimp species were Penaeus monodon (tigershrimp), Penaeus indicus (Indian white shrimp), and Metapenaeus monoceros(brown shrimp). The contribution of brown shrimp was highest for entire timeperiod and varies from 53-72% of the total catch. On the other hand white shrimpcontributes lowest portion (1-13%) of the total catch. The contribution of the mainand highest valued tiger shrimp was lowest (5.6%) in the year of 1999-00 andhighest (18.8%) in the year of 1991-92 (Figure-3). The percent contribution of tigershrimp was decreased slowly but increased in case of brown shrimp and forIndian white shrimp the contribution was stable (Figure-4).http://www.bdresearchpublications.com/journal/

Catch Composition for Main Marine Shrimp Species95Figure 3. Percent contribution of major shrimp species by shrimp trawlers (Source:BMFSMU, DoF )Figure 4. Trends of percent contribution of major shrimp species by shrimp trawlers(Source: BMFSMU, DoF )The CPUE for tiger shrimp, brown shrimp and Indian white shrimp werevaried from 23-89, 191-465 and 7-65 kg d -1 , respectively. The highest CPUE with 465kg d -1 (65.4% of the total catch) was observed in the year of 1990-91 by thecontribution of the brown shrimp. On the other hand the lowest CPUE with 7 kg d -1(1.3% of the total catch) was observed in the year of 1909-10 by the contributionof the Indian white shrimp (Figure-5).http://www.bdresearchpublications.com/journal/

Uddin et al.96Figure 5. Trends of catch per unit effort (CPUE) of major shrimp species by shrimptrawlers (Source: BMFSMU, DoF)DiscussionThe industrial fishing fleet consists of two types of fishing trawler namelyshrimp trawler and fin fish trawler. Though the total number of industrial fishingtrawler increased rapidly but the number of shrimp trawler was in a position ofbellow than fifty. This is due to some initiatives for introduction of new fish trawlersin recent years, but introduction of new shrimp trawler is completely prohibited bythe Government. This is due to protect the sea bed and conserve the nature asshrimp trawler dwell on sea bed and cause for destruction of marine flora andfauna.The only coherent database that exists at present is that of statisticsgathered from the industrial trawl fishery. Analyzing and reporting data as actualnumber of fish caught, fisheries data are typically reported as CPUE. The datahere only points to (a) overall reductions in the CPUE for shrimp as a whole, butmore specifically (b) substantial declines in the CPUE for tiger shrimps. Amongother shrimp species the white shrimp is believed to be over-exploited for nopotential benefit and the brown shrimp has remained stable. But this information isoutdated and there is a strong need to be updated and adequately explainedfor ready use in the development of management programs. The excessivepressure on different species is evident from the reports of Islam et al. (1993),Mustafa and Khan (1993), Khan et al. (1994) and Khan, S.M. and M.S. Haque.(2003). It is true however that the situation is dynamic and much of thedimensions, but not necessarily the characters of the identification, havechanged which is apprehended to be deteriorated further.The stock of main target and highly commercial valued species black tigershrimp P. monodon in particular is under threat from the sides. Only less than 10%of the virtual population of this species and more than 80% of the white shrimp P.indicus were allowed by the shrimp fry collectors (Khan et al. 1997) to go back tothe sea. Brackish water estuaries provides spawning support and serves as nurseryground for the marine fauna, which visit the estuarine environment during theearly phases of the lifecycle. Most of the members of the visiting fish/shrimp stocksare over-fished in this ground. This multi-species and multi-gear complexities of thedynamics are of fishing in the coastal areas has made the fisheries managementhttp://www.bdresearchpublications.com/journal/

Catch Composition for Main Marine Shrimp Species97decisions extremely difficult. The overall penaeid shrimp stock is under pressure.Shrimp fry collection fishery, the estuarine setbag net (ESBN) fishery (to catchjuveniles of miscellaneous marine fauna) and the shrimp trawl fishery (to catchbrood shrimps) are the three major destructive fishing gears, the combined effectof which has made the coastal fisheries resource base too sensitive to depletion.The combined impact of the indiscriminate fishing by these fisheries has made thecoastal fisheries resource base too sensitive to depletion. The impact of the trawlfishery on the shrimp PL fishery and the vice-versa is difficult to quantify, largelybecause the two fisheries came into operation almost at the same time. But thenegative impact of them on the ESBN fishers was visible (Khan et al.1997).ConclusionsThe marine fisheries sector has been suffering from chronic disintegrationand mismanagement that have led to many consequences. Most of thecommercially important fish stocks are either overexploited or under threat. Theissues of sustainable resource use is discussed and identified in detail in order tobe able to seek the appropriate solutions. However, it should be reemphasizedthat over-fishing on spawning stocks (recruitment over fishing) is considerablewithin the shrimp trawl fishery which impacts on juveniles migrating to inshorewaters thereby restricting recruitment of a significant part of the population. Onthe other hand the growth over-fishing by the small-scale artisanal fleet is anotherserious issue that needs special attention, under the present situation that fishing inthe inshore areas is no longer remunerative.RecommendationsIn order to combat future tragic situation of declining fish production inmarine waters, both enhanced coastal aquaculture production and reductionof post-harvest loss would go side by side. Some recommendations are asfollowsi.All destructive gears like the estuarine set bag net, beach seining, shrimpfry collection push nets should be gradually removed and be successivelyreplaced by eco-friendly gears.ii. Dependable database should be created and updated as regard thestocks, catch and efforts, abundance, shrimp fishers, small-scale fishers etc.and their socio-economic status;iii. Closed season during breeding season and areas (Marine reserve) forconservation of gravid female shrimp and fish species should beimplemented.iv. The research areas identified immensely need to be considered for properimplementation. The government and concerned agencies have tocommit long-term funding and capacity building for research backed byqualified scientific manpower.AcknowledgementsThe authors would like to acknowledge the Skippers and the Crews of the shrimptrawlers those were engaged in fishing in the EEZ of Bangladesh and made a verygood catch report for the tenure period. Special thanks are due to the Staff andOfficers of Marine Fisheries Office, Chittagong and also BFRI officers for their kindsupports. The authors are also indebted to BOBLME for valuable and technicalsupport on draft writings and are also grateful to all anonymous reviewers forimproving this manuscript.http://www.bdresearchpublications.com/journal/

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