Reproductive ecology of demersal elasmobranchs from a data-deficient fishery, Pacific of Costa Rica, Central America

摘要

The elasmobranch bycatch associated with the Costa Rican deepwater shrimp fishery is mainly comprised of four species: Raja velezi, Mustelus henlei, Zapteryx xyster and Torpedo peruana. In data-deficient fisheries such as this one, knowledge of the reproductive ecology of a species may serve as a valuable management tool to determine its vulnerability and apply precautionary measures to ensure its long-term conservation. This study examined the reproductive ecology of R. velezi, M. henlei, Z. xyster and T. peruana based on data collected during demersal trawling along the Pacific coast of Costa Rica, Central America. A total of 290 trawls was analyzed at depths of 18-350 m (March 2010-August 2012). While R. velezi, M. henlei and Z xyster matured at similar sizes (range: 37-60 cm TL), T. peruana matured at a larger size (70 cm TL in females). The four elasmobranch species exhibited strong sex and size segregation patterns, which were mainly influenced by depth. Adults were more common at depths >50 m, whereas neonates and gravid females were more abundant in shallow estuarine waters (<50 m). Moreover, large aggregations of immature R. velezi and M. henlei occurred near coastal wetlands, bays and estuaries of the central Pacific region. These results suggest that shallow estuarine habitats may be important for early life stages of demersal elasmobranchs caught in the Costa Rican trawling fishery. However, our knowledge of critical habitats for elasmobranch along the entire Pacific of Costa Rica is still limited, and thus future studies are needed to identify and understand the role of these habitats in the early life-history of sharks, skates and rays