Bay of La Paz

Studying the habitat use of the critically endangered scalloped hammerhead shark

Until 1980, there were many aggregations of the scalloped hammerhead shark Sphyrna lewini along the east coast of Baja California Sur. Fishing pressure has greatly reduced their populations, and the IUCN classified this species as “critically endangered” in 2019.

In Mexico, about 3,000 tons of scalloped hammerheads are fished annually, and 70% of that catch consists of pregnant females, neonates, and juveniles. The Gulf of California contributes about 67% of the national shark production, and the scalloped hammerhead remains one of the most exploited species.

In collaboration with the local non-profit Pelagios Kakunja, we are working to protect this critically endangered species through a multi-faceted approach. Firstly, we are advocating for the creation of a large marine protected area that includes several key coastal nurseries and aggregation zones. To improve the efficacy of this park, we are studying the species’ habitat use, connectivity, population structure using drones, satellite and acoustic tags, baited cameras, and capture and recapture studies.

Secondly, we work directly with local fishing communities to develop the infrastructure and capacity for alternative income sources such as ecotourism, shark monitoring, and illegal fishing surveillance. We developed the plans for the proposed park in conversation with communities to ensure that their voices were represented. Everytime we go into the field, we hire local fishermen to serve as field technicians and guides. Our time spent in the pangas at dawn and dusk create spaces for bi-directional learning to occur.

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Updates on Hammerheads