Fish assemblage and structure as well as hydrological parameters at Karatoya Fish Sanctuary, Panchagarh, Bangladesh

Spatiotemporal variations in fish assemblage structure was studied from January to December 2015 in order to understand the impacts of the sanctuary on ichthyo-faunal diversity and to determine the indices and major hydrological factors in six sampling stations of Karatoya Fish Sanctuary sectioned in the River Karatoya. A total of 69 fish species were obtained from this sanctuary including 21 threatened species where Aspidoparia jaya, Pethia ticto, Puntius sophore, Canthophrys gongota and Barilius barna were the major contributory species (>4.17%) both in space and time. The uppermost species richness and abundance were viewed in January and lowest in May. Based on analysis of similarities (ANOSIM), fish assemblages were significantly different in all stations (p<0.001, R=0.15) and months (p<0.001, R=0.62). Through two-dimensional nonmetric multidimensional scaling (nMDS) and cluster analysis based on Bray-Curtis similarity index, assemblages were alienated into two groups at a value of 42% and 28% partition for station and month, respectively. Canonical Correspondence Analysis (CCA) recognized considerable relations between the number of fishes and hydrological parameters where dissolved oxygen (mg L-1) and water temperature (ºC) were the main leading factors in shaping the fish assemblage structure