Integrating spatial management measures into fisheries: The Lepidorhombus spp. case study

Most fisheries management systems rely on a set of regulatory measures to achieve desired objectives. Controls on catch and effort are usually supplemented with gear restrictions, minimum landing sizes, and in the framework of the new common fisheries policy, limitation of discards and by-catch. However, the increasing use of spatial management measures such as conservation areas or spatial and temporal area closures faces new challenges for fishery managers. Here we present an integrated spatial framework to identify areas in which undersized commercial species are more abundant. Once these areas are identified they could be avoided by fishers, minimizing the fishing impact over the immature fraction of the stocks. In particular we applied this methodology to two species of megrim, Lepidorhombus whiffiagonis and L. boscii, in North Atlantic Iberian waters (ICES Divisions 8c and 9a), analyzing fishery-independent data provided by bottom-trawl surveys and environmental data through Bayesian spatial models. Results show that species exhibit species-specific spatial patterns, and we identified sensitive areas that could be used for conservation purposes. We discuss integrating technical measures together (e.g. Minimum Conservation Reference Size and spatial closures) could be a more effective approach for fishery management and this case study could be extended to other species.