The scalloped hammerhead shark, Sphyrna lewini, is one of the most affected specie by overfishing and “finning”; in fact, the IUCN Red List considers it as threatened, endangered. In Costa Rica this shark is caught by different fisheries. In coastal waters the juveniles and pregnant female are vulnerable to trawling shrimp boat, gill nets and bottom lines of artisanal fishermen; in pelagic waters, adults are mostly caught by pelagic long-lines. In the Pacific coast of Costa Rica there are different critical habitats for scalloped hammerhead shark, because juveniles used the coastal waters of estuaries, bays and mangrove as nursery areas, where rich nutrient waters provide food and protection to pups and juveniles. In turn, the adults migrate to pelagic waters to seamounts or oceanic islands (like Coco’s Island) where they find food and cleaning stations. Despite the scalloped hammerhead shark´s condition as an endangered species, in Costa Rica regulations to improve the juveniles and newborns´ s conservation do not exist. Due the above, this project aims to collect scientific data on shark fisheries, in order to identify and describe critical habitats for the scalloped hammerhead shark. In order to accomplish this aim, we started a shark tagging program (conventional and acoustic) in Golfo Dulce, where we reported high relative abundance of juveniles of hammerhead shark. Thanks to this program, we are studying the habitat use and the population parameters of Sphyrna lewini in Golfo Dulce.