Assessment of Species Specificity of Fishing Gears and Fish Diversity Status in the Andharmanik River of Coastal Bangladesh

Background and Objective: In Southern Bangladesh, the Andharmanik river is an ichthyofaunal resourceful coastal water body due to adjacent to the Bay of Bengal. An investigation has been undertaken to identify available fishing gears and their specificity on the fishes as well as the fish diversity status of the river for a period of one year from November, 2014 to October, 2015. Methodology: The PRA tools were employed for data collection. Results: The survey revealed total 17 different types of fishing gears under 8 major groups of net. A total of 48 fish species under 10 orders and 26 families were identified by using these gears. Mesh size of the gears were varied from 0.508-15.24 cm depending on targeted fish species and some of them were very selective to specific species. Fish diversity was assessed by using Shannon-Weiner index (H), evenness (E), Simpson’s dominance index (D), Simpson’s index of diversity (1-D) and Margalef’s index (d) ranges between 3.33-3.42, 0.67-0.73, 0.042-0.048, 0.952-0.958 and 4.72-5.24, respectively for three stations of the river. The highest fish occurrence belongs to the Perciformes order (33.33%) and lowest five orders viz., Aulopiformes, Beloniformes, Osteoglossiformes, Pleuronectiformes and Tetraodontiformes were found as same (2.08%) among the total fish population. Conservation status disclosed that out of 48 species 3, 3 and 8 species belonged to endangered, critically endangered and vulnerable, respectively. Conclusion: The fishes of the river were under pressure by different non-selective, illegal and restricted fishing gears. So, scientific based management is prerequisite to guide the fish fauna from near extinction.