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Landing Trends, Species Composition and Percentage Composition of Sharks and Rays in Chittagong and Cox’s Bazar, Bangladesh

Roy Bikram Jit
Scientific Officer
Marine Fisheries Survey Management Unit, C.G.O. Building - 2, 6 th Floor, Agrabad, Chittagong, Bangladesh

Md. Fokhrul Alam
Scientific Officer
Marine Fisheries Survey Management Unit, C.G.O. Building - 2, 6 th Floor, Agrabad, Chittagong, Bangladesh

Md. Gaziur Rhaman
Scientific Officer
Marine Fisheries Survey Management Unit, C.G.O. Building - 2, 6 th Floor, Agrabad, Chittagong, Bangladesh

Nripandra Kumar Singha
Scientific Officer
Marine Fisheries Survey Management Unit, C.G.O. Building - 2, 6 th Floor, Agrabad, Chittagong, Bangladesh

Aysha Akhtar
Assistant Professor
Institute of Marine Sciences and Fisheries University of Chittagong, Bangladesh

Abstract/ Executive Summary:

The study was conducted from April, 2006 to June, 2010 on landing trends, species composition and percent contribution of sharks and rays by weight using the catch records of Marine Fisheries Survey Management Unit, Chittagong from two landing centers Fishery ghat, Chittagong and BFDC ghat, Cox’s Bazar. This study identified 27 species in total representing 11 species of shark (04 families) and 16 species of ray (09 families). The highest landing volume (134 MT) and contribution (76%) to total catch for the whole sampling period was found from Scoliodon laticaudus followed by Rhizoprionodon acutus (108 MT or 55%), Carcharhinus melanopterus (75 MT or 38%), Sphyrna zygaena (49 MT or 26%), Chiloscyllium indicum (38 MT or 20%), Eusphyra blochii (22 MT or 11%) Galeocerdo cuvier (21 MT or 10%) and other (03 MT or 2%). Species which occurred least were placed in the ‘other’ category comprising Carcharhinus amblyrhynchos, Stegostoma fasciatum, Carcharhinus leucas and C. falcifomis. Among rays, the landing volume and resultant percent contribution to overall catch found highest from Himantura uarnak (219 MT, 120%), followed by Himantura walga (158 MT or 60%), Himantura bleekeri (68 MT or 34%), Rhinobatos granulatus (29 MT or 18%), Gymnura micrura (12 MT or 7%) Mobula diabolus (11 MT or 5%), Rhynchobatus djiddensis (10 MT or 5%), Aetomylaeus nichofi (9 MT or 4%), Rhinoptera javanica (8 MT or 4%) and Narcine timlei (7 MT or 4%) and other species with least occurrence (5 MT or 4%). Species in other category consisted of Gymnura poecilura, Rhina ancylostoma, Himatura gerrardi, Anoxypristis cuspidata, Himantura undulata and Taeniura. Sps. Landing of different species were found to vary from month to month and year to year throughout the sampling period. To make absolute comment regarding these trends of occurrence, base line biological information together with long term catch record for size distribution was needed which could not be work out from the present data set. However, total landing of sharks and rays were found to be on slight decline.

Keywords: Shark, Ray, Species Composition, Elasmobranches Fishery, Landing Trend, Catch Data, Abundance, Percent Contribution

Location: The laboratory of Marine Fisheries Survey Management Unit (MFSMU), Chittagong, Bangladesh.

Start Date: 00-04-2006

End Date: 00-06-2010

Program Area: Resource Development and Management

Commodity: Aquatic animal

Objectives:

To determine the landing trends, species composition and percent contribution of sharks and rays from April 2006 to June 2010 in the coasts of Chittagong and Cox’s Bazar.

Methodology:

Sampling Stations: The study was under taken for about 04 years starting from April 2006 up to June 2010 at two fish landing centers i.e. BFDC ghat of Cox’s Bazar district and Fishery ghat of Chittagong district situated at the south-eastern part of the Bay of Bengal. These two landing centers were selected because the major landing of shark and ray is done here and the wholesale and retail market is also located in these two places. Data collection and statistical analysis Species wise landing data were recorded both at landing stations and on board commercial fishing vessels. Data were collected from four field visits per month i.e. new - moon, full - moon, first quarter and last quarter. The species were preserved in 5% formalin just after collection from the landing centers and then sorted in the laboratory of Marine Fisheries Survey Management Unit (MFSMU), Chittagong, Bangladesh. Species were identified to the lowest possible taxonomic position by consulting the following resources: Rahman et al. (2009), Albert et al. (2007), Kazunari et al . (2007), Raje et al. (2007), Ramon (1994), Quddus et al. (1988), FAO (1984), Munro (1982), Day (1978) and Hussain (1972). Sampling was performed through interviews with the Arartdar ( assemblers ), boat owners and fishermen of the boat. Information was collected on trip duration per month, number of fishing days and fishing effort. The length (total length for shark and disc width length for ray) and weight of the fishes were measured directly by using balance and measuring tape. The percentage contributions of shark and ray species were calculated by weight. The species wise weight was measured in kilogram and then it was converted into metric tons (MT). Data processing and analysis was done by MS Excel.

Source of Information: International Journal of Research in Agricultural Sciences, Volume 1, Issue 4, Pp: 216-224, (2014) ISSN (Online): 2348-3997)

Article Link (Online Journal): http://www.ijras.org/administrator/components/com_jresearch/files/publications/IJRAS_53_Final.pdf

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

In the present study, a brief image on the status of shark fishery in Bangladesh has been represented. On the basis of major findings some limitations and necessary measures are detailed as below: Key features (such as nostrils, gill slits, mouth position, various lengths, body coloration etc.) used to make distinctions between different species of shark s and ray s are so c lose that it often makes confusion. Therefore, detail species profile needs to be developed with local names, valid scientific names, pictures and status in IUCN red list. Further, for easy and correct identification at field level, guide book and training on taxonomy need to be provided for the data collectors. In absence of long term data record (both species and area wise), it becomes difficult to make absolute comment on changes in species composition over time and area, landing pattern, abundance, size distribution and vulnerability of a species. Existing data recording system is not so consistent and accessible to all stakeholders. At present, detail catch data on shark and ray fishes is maintained from MFSMU, Chittagong which should be extended to the south western coastal districts as well. In this regard, the capacity of MFSMU, Chittagong needs to be strengthened. Information on biological aspects, population parameters (e.g. growth rate, mortality, exploitation rate, recruitment pattern, maximum sustainable yield, biomass etc.), fishing effort (e.g. fish days, gear, mesh size, fishing depth etc.) and impacts of environmental changes on shark fishery are still very limited to interpret catch data. Therefore, accumulation of data and information together with need based research is of prior importance. Shark fishery although has a minor contribution to the total catch, its potential to the economy and biodiversity of our country is noteworthy. Therefore, a National Plan of Action (NPOA) for sustainable management and development of the fishery is an urgent need.

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