Protecting a critically endangered hammerhead shark from their nurseries


Published: 01/04/2020

Sphyrna lewini​ is one of the nine species of hammerhead sharks, and lives around the world in the tropics. According to the IUCN, this species is categorized as Critically Endangered since its populations have declined due to fisheries both as bycatch and as directed fishing, since their fins are highly valued in the international fin market. This shark has an interesting behavior in which females come to coastal waters called nursery areas to deliver their pups. Juveniles remain in these areas for their first years so coastal marshes and wetlands are an important habitat for their nurturing. In Costa Rica these areas are threatened both by habitat degradation and by fisheries.
"Taxidermy of hammerhead shark (Sphyrna lewini) juveniles".Taxidermy of juvenile hammerhead sharks from nursery areas in the northern pacific of Costa Rica
After this first stage of life, adults move to open waters and islands, where constant migration is observed. Also in open waters and near the Cocos Island this shark is specifically targeted for its fins. Protecting this highly mobile animal that can migrate long distances is a hard task since its populations are not in a specific geographic place during all their lifetime. Also in the Eastern Tropical Pacific, population structure is not well known. Is it one population or are there several? Do females prefer specific nursing grounds to deliver their pups? Understanding population structure and movements of hammerhead sharks is vital to establish regional management and policies.
In the BIOMOL lab we are working in an investigation that aims to determine connectivity and genetic population structure of ​S. lewini​ in various coastal nursing areas in Guatemala, Costa Rica and Panamá. The results of this research will be important to provide biological information for management plans that will aim to protect specific important geographical areas for this species persistence.
"Hammerhead shark with a school of fish".


population genetics

endangered sharks

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