Impacts of temporal and spatial fishing ban on fish and shell-fish biodiversity in two fish sanctuaries in Bangladesh

Abstract

Fishing ban, a widely practiced fisheries management tool which impacts the fish biodiversity within and beyond the sanctuary areas. The two months total fishing ban in five riverine hilsa sanctuaries in Bangladesh has been reported to increase hilsa production which also may have impact on overall fisheries biodiversity. Present study was carried out to assess the impacts of temporal and spatial fishing bans on fisheries (fish and prawn/shrimp) biodiversity in two riverine hilsa sanctuaries. Two sites, namely, Chandpur (S1) and Shariatpur (S2) landing fish caught within the sanctuary areas of the Meghna and Padma river respectively, and two sites, namely, Naryanganj, (O1) and Munshiganj (O2) landing fish caught outside the sanctuary area of the same rivers were selected. Fish and prawn/shrimp samples (10% of total catch) caught by different gears were collected three times (Jun, August and October) from pre-contacted fishers and identified based on morphometric and meristic characteristics. A total of 77 species of fish belonging to 31 families and 11 orders were identified. Cyprinidae was the most abundant with 23.33% individuals and also in all sites and months. In addition, 9 Species of prawn and 1 species of shrimp were also identified. Freshwater-estuarine living and omnivorous fish species were dominant in number among different habitat and feeding groups. Among all species, 20.78% of fish species were found to be threatened according to IUCN conservation status and there was no difference between sanctuary and open areas. The species diversity and evenness evaluated by, equitability (EH) and richness. The Margaleaf’s richness index (d=9.3846) and Shannon-Weiner Diversity Index (H=2.0344) obtained from whole samples indicates high species richness and diversity. However, all sites were less diverse compared to overall value. The fish community was more diverse within the sanctuary compared to outside in Padma river (S2 > O2), while it was opposite in case of the Meghna river (O1 > S1). Species diversity was highest in October compared to June and August. The findings of the present study suggest that the impact of fishing ban on riverine fisheries biodiversity is variable among different riverine ecosystems.