Climate change drivers influencing Indian mackerel fishery in south-eastern Arabian Sea off Kerala, India

Abstract

The Indian mackerel Rastrelligerkanagurta(Cuvier, 1816) is one of the most important marine fishery resources along the south-eastern Arabian Sea along the coast of Kerala, south India. The effect of selected environmental variables on the Relative effort (Effort) and weighted catch per unit effort (cpue)of the fish were investigated using simple correlation and Path analysis. Six major oceanographic variables, namely sea surface temperature (SST), sea surface chlorophyll-a concentration (SSC), sea surface salinity (SSS), Precipitation (Pr) Indian Ocean Dipole (IOD) and Southern Oscillation Index (SOI) (ENSO index) were selected for the present study. Among these SST had the highest direct negative effect (-0.282, p<0.01), followed by SSS (-0.152, p<0.1) and IOD (-0.006, p<0.01). The highest positive direct effect on the cpue was exhibited by Pr (0.514, p<0.001) followed by SSC and SOI (0.178, p<0.01). The environmental variables also exerted indirect effects on cpue through Effort. The residual variance indicated that there are spurious effects exerted by environmental variables not included in the study. According to the coefficient of determination (R2), the relative importance of the influence of causally dependent environmental variables on the cpue of Indian mackerel is Pr> SSC >SSS.