Diversity of fishery resources and catch efficiency of fishing gears in Gorai River, Bangladesh

Abstract

Gorai River is one of the important rivers in Bangladesh for rich aquatic biodiversity. The river is originated from the Ganges-Padma River system, a trans-boundary river between India and Bangladesh. Once the river was rich in fish biodiversity, but due to man-made and natural causes the availability of fish reduced drastically. A comprehensive analysis of fish diversity indices, gear efficiency, catch composition and decline causes of fish diversity in Gorai River, Bangladesh was accomplished. The data were collected on monthly basis from January to December 2018 from three major fishing sites of the river. A total of 62 fish and 2 prawn species under 12 orders and 24 families were recorded. Cypriniformes was the leading order consisting 27% of the total catch. The mean values of Shannon-Weaver diversity (H 0 ), Simpson's index (1-D), Margalef's richness (d) and Pielou's evenness (J 0 ) indices were recorded as, 1.478 AE 0.495, 0.57 AE 0.197, 15.115 AE 4.435 and 0.481 AE 0.152, respectively. At the similarity of 58.7%, two groups were attained in the cluster analysis and the Non-metric Multidimensional Scaling (nMDS) showed 40% similarity among the three sites in twelve months based on the Bray-Curtis similarity matrix. The highest and lowest CPUE were recorded from seine net (5.2 AE 1.72 kg gear À1 haul À1 ) and hook & long lines (0.0135 AE 0.0015 kg gear À1 haul À1 ), respectively whereas, highest and lowest gear efficiency were recorded from lift net (0.321 AE 0.036 kg gear À1 person À1 hour À1 ) and fish trap (0.0005 AE 0.0002 kg gear À1 person À1 hour À1 ), respectively. Alternatively, the highest fish catch was recorded on April (21228 AE 464.38 kg) and lowest on August (3855 AE 138.21 kg). According to the fishermen fish biodiversity of the Gorai River declined day by day due to overexploitation, destructive fishing practice, pollution, construction of obstacles for fish movement, and natural causes like siltation. Proper implementation of fish acts and regulations, use of authorized fishing gear, community-based fisheries management, sanctuary establishment and management, stocking of fish fingerling, and raising public awareness can play a great role in enhancing and conserving fish biodiversity in the Gorai River of Bangladesh.

Establishment of a fish sanctuary for conserving indigenous fishes in the largest freshwater swamp forest of Bangladesh: A community-based management approach

“…Results from nMDS revealed a 40% similarity across all seasons. Tikadar et al. (2021) also found same results among all months.…”

“…However, around 64 species of those are now endangered, critically endangered, or in vulnerable conditions ( IUCN Bangladesh, 2015 ). Indiscriminate fish harvest, climatic degradation, and numerous anthropogenic causes adversely affect the fish biodiversity in the natural waterbodies ( Nagelkerken et al., 2017 ; Islam et al., 2019 ; Pandit et al., 2021 , 2022 ; Tikadar et al., 2021 ). In particular, a considerable number of freshwater riverine fish species have become highly endangered due to habitat degradation as a consequence of extreme anthropogenic intervention ( Rahman et al., 2012 ).…”

Heavy Metal Pollution Reduced the Potentiality of Pen Culture in the Wetland Aquaculture in an Urban Area of Bangladesh

“…Based on the current research, the authors suggest new measures for conserving fish diversity by minimizing the threats to these Belai beel wetlands. The reduction or minimization of the impacts of industrial activities [17,36], minimizing the uses of harmful insecticides and pesticides in agricultural crops, the proper application of fishing laws, education of fishermen communities [37] and raising public awareness can be effective for the conservation of existing fishery resources, and national strategies are being formulated for policymaking, monitoring and implementation in the Belai beel wetlands of Bangladesh [17,[38][39][40]. Determining the appropriate strategies with updated status information is also essential for conservation management and such data would help to focus the overall status of freshwater fish in the Belai beel, Bangladesh [40].…”

A long-term ichthyoplankton monitoring program suggests climate-induced environmental variabilities changed fish communities in the Hudson River estuary

“…The Margalef index (d) is one of the simplest measures of biodiversity which accounts for sampling effects and emphasizes the component of species richness (Magurran and McGill, 2011;Garcıá-Seoane et al, 2016;Shaha et al, 2022). While the Simpson index (D) measures biodiversity with incorporation of species' abundance, which gives more weight to the abundant species and is less sensitive to additional rare species and is independent of sample size (Magurran and McGill, 2011;Garcıá-Seoane et al, 2016;Tikadar et al, 2021). The increasing d is indicative of increases in species richness, and the increasing D is indicative of increases in species evenness in the fish assemblage (Tikadar et al, 2021).…”

“…Biodiversity has been widely used as an indicator to monitor and evaluate ecological health of aquatic or terrestrial systems (Dasgupta et al, 2017;Tu et al, 2020;Aziz et al, 2021;Tikadar et al, 2021). In general, higher biodiversity is indicative of a healthy ecosystem (Pawluk et al, 2021), suggesting a suitable environment with diverse functional guilds.…”