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

Abstract

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 nichofii (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.