Environmental preferences of sharks bycaught by the tuna purse-seine fishery in the Eastern Pacific Ocean

Sharks play important ecological roles in marine ecosystems. However, due to their life-history traits and low resilience, their vulnerability increases with overexploitation. The Eastern Pacific Ocean (EPO) purse-seine fishery catches several pelagic sharks as bycatch. Therefore, describing the environmental preferences of bycaught sharks is crucial to improve fisheries management. This study aims to describe the environmental preferences and spatiotemporal distribution of most bycaught shark species within the EPO through Generalized Additive Models (GAMs). Results show that the silky shark (C. falciformis) is bycaught in oceanic waters on floating objects, and close to the coast in unassociated and dolphin sets. This species inhabits warm waters with low or high productivity. Oceanic whitetip shark (C. longimanus) is bycaught in warm and oceanic waters with low productivity. Meanwhile, scalloped and smooth hammerhead sharks (Sphyrna lewini & S. zygaena) are bycaught in temperate and productive waters offshore of Peru. The obtained results allowed us to identify hotspots where fisheries management can be implemented, improved, or modified (e.g., temporal closures) for reducing shark bycatch.

Automated summary

The study used Generalized Additive Models to describe the environmental preferences and spatiotemporal distribution of most bycaught shark species in the Eastern Pacific Ocean. Different shark species were found to be bycaught in different water and productivity environments. The results identified hotspots where fisheries management could be implemented, improved, or modified to reduce shark bycatch.