A Preliminary Evaluation of Cobia Rachycentron canadum (Linnaeus, 1766) Stocking in Northeastern Brazil: Lessons From an Experimental Project

The cobia (Rachycentron canadum) is important to fisheries in Northeastern Brazil. To restore stocks in Rio Grande do Norte, cobia were stocked and the fishery was monitored over 4 years. We evaluated effects of stocking on cobia size composition in this data-limited fishery to understand stocking limitations and explore possibilities for future projects. Total length of cobia was significantly shorter after stocking than before stocking, with mostly small fish caught mainly by nets, an unusual pattern for cobia. Total length also varied significantly among bottom types. Most of the cobia harvested were below the size at first maturity, which suggests that stocking increased the catch, but most fish harvested were immature, thereby potentially hindering stock recovery. For future projects, we recommend against the use of plastic tags for tagging hatchery cobia and propose releases that emulate natural spawning dynamics, alongside releasing fish at older ages. Further, we recommend robust post-stocking fishery monitoring, and management strategies, such as a release of net-caught cobia in the initial 2 years and incorporating validated fisher knowledge into decision-making.