Selectivity of Fishing Gears and Their Effects on Fisheries Diversity of Rabnabad Channel of Patuakhali District in Bangladesh

The Rabnabad is a marine channel, harbor of plentiful aquatic resources, situated at southern district of Patuakhali in Bangladesh. An investigation has been carried out on three different selected spots (S1, S2 and S3) of Rabnabad channel to identify fishing gears used for fishing and their potential effects on available fisheries diversity for a period of 8 months from February 2015 to September 2015, employing a prepared questionnaire. The study explored total 21 fishing gears under 8 major groups of net. In total, 54 species of fishes were identified belongs to 10 orders and 27 families in the catches of these gears. The order basis percentage analysis of the fish species executed the highest occurrence belongs to the order Perciformes (31.48%) and lowest for five ordersviz., Aulopiformes, Beloniformes, Osteoglossiformes, Pleuronectiformes and Tetraodontiformes were found in the percentage as 1.85% (for each) of the total fish community. Out of 54 species, 7, 2 and 7 species was recorded as endangered, critically endangered and vulnerable, respectively. Calculated Shannon- Weiner index (H), Gibson’s evenness (E), Simpson’s dominance index (D), Simpson’s index of diversity (1-D) and Margalef’s index (d) of fishes ranges between 3.22-3.30, 0.54-0.59, 0.04-0.05, 0.95-0.96 and 5.67-6.10, respectively. It is worse that numerous non-selective and restricted fishing gears are used which lead to unsorted catches, consequently, diversity of fish fauna are decreasing from the channel. For sustainability of these resources, proper management and conservation is crucial to guard the species diversity.