Stock status indicators for Cobia Rachycentron canadum in the Indian EEZ

Abstract

Regional fisheries for cobia (Rachycentron canadum) along the Indian coast was assessedusing length-based stock status indicators. Drift gill nets-cum-hook and line fisheries landedbigger sized cobia as bycatch while multi-day mid-water trawls landed juveniles. Dominantsize groups in the landings along the west coast were 40–160 cm and 60-120 cm on theeast coast. Gear selectivity operating at regional levels because of the multi-gear fisheriesand fishing grounds of the Indian EEZ affects the size distribution of fish caught. Comparedto drift gill net-cum-hooks and line units targeting large pelagics in deeper waters, smallersize groups of cobia dominated as bycatch in trawls. The length at first capture (Lc50) beingsmaller than the estimated length at first maturity of about 60 cm, implementing size-basedoutput controls such as Minimum Legal Size (MLS) is suggested. The indicators for fishingmortality rates (Fmax) on the cobia stocks were on the higher side in certain locations only,but being part of the multi-species bycatch mix, there is little scope to introduce fishinggear regulations solely for cobia. However, the option of short-term, targeted spatiotemporaleffort regulations with fishers’ participation can be explored, based on the stockassessments made at local or regional levels. Keywords:Cobia, Fishery indicators, Length-based indicators,Minimum Legal Size, Rachycentron canadum, Stockstatus