CARACTERIZACIÓN DE LA PESCA DEL TIBURÓN MARTILLO, SPHYRNA LEWINI, EN LA PARTE EXTERNA DEL GOLFO DE NICOYA, COSTA RICA

The scalloped hammerhead shark (Sphyrna lewini) is one of the shark species most impacted by overfishing, and is currently listed by the IUCN Red List as an Endangered. This research sought to charac terize the distribution of S. lewini in the external area of Gulf of Nicoya, central Pacific coast of Costa Rica, based on observations from a coastal artisanal fishery. From March 2006 to May 2007, we analy zed scalloped hammerhead shark landings by members of the Tarcoles Artisanal Fishermen’s Cooperative (CoopeTarcoles R. L.), who operate in the outer part of the Gulf of Nicoya. We measured the total length of each shark, recorded the reported location of capture, and the gear used. In total, we recorded data for 273 sharks landed. We determined that total length holds a positive linear relationship with the depth of the fishing area (R 2 = 0.4296, *** p <.0001) as well as with the distance from the mouth of the Tarcoles River (R 2 = 0.4052, *** p <.0001). The smaller sharks (pups) were caught in a fishing site known as Penon, slightly north of the mouth of the Tarcoles River, where the waters are shallow, turbid and highly productive, providing food and shelter for the pups. As pups mature and attain larger sizes, they move towards deeper waters away from the Tarcoles River, out of the Gulf of Nicoya. We identify Penon as a primary nursery for scalloped hammerhead sharks, and recommend management actions that seek to reduce fishing effort between March and May, when pups are born.