Temporal variations in catch composition of stationary bagnets along Maharashtra coast in relation to environmental factors.

Abstract

Stationary bagnets are one of the most extensively operated traditional fishing gears along Maharashtra Coast. Despite being the most important traditional gear of the State, no systematic studies on the temporal variations in catch composition and the influence of environmental factors on the bagnet fishery of Maharashtra Coast have been conducted till date. Thus, the present study aimed at evaluating temporal variations in catch composition and the influence of environmental variables on the same. To this end, fishing experiments and environmental assessments were conducted every month at four stations for two years, and analysed to achieve the objectives. A total of 156 species belonging to 63 families were recorded in the catch. The most dominant species in the catch were Harpadon nehereus (19.16%), Acetes spp. (14.24%), Nematopalaemon tenuipes (8.97%), Coilia dussumieri (5.27%), Chrysaora sp. (3.98%) and Lepturacanthus savala (2.31%). No significant spatial variations were observed for the different resources, whereas temporal variations were significant. Major environmental variables (temperature, salinity, pH, DO, BOD, current speed, turbidity, TSS, ammonia, phosphate, nitrate, nitrite, silicate, chlorophyll-a, phytoplankton and zooplankton) were analysed and compared among the seasons. Significant temporal variations were observed for all the environmental variables. Catch composition and environmental data were subjected to different multivariate analyses. The results of cluster analysis, ANOSIM and SIMPER established a significant difference in catch composition among the seasons. The diagnostic species for each season were identified through CCA and SIMPER. The results of CCA, Pearson's correlation analysis revealed that current speed, temperature, salinity, pH, DO, turbidity, chlorophyll-a and plankton density play significant roles in structuring the catch composition across the different seasons and current speed exerts maximum influence on catchrate. The information from the study could be used as baseline data for framing management measures for a sustainable bagnet fishery along Maharashtra Coast.