Shark Depredation and Unwanted Bycatch in Pelagic Longline Fisheries: Industry Practices and Attitudes, and Shark Avoidance Strategies

This document examines shark depredation and unwanted bycatch in pelagic longline fisheries, outlining the industry context, geographic scope, data sources, and mitigation options. It synthesises observer records, fleet logbooks, regulatory reviews, and interviews across the Atlantic, Mediterranean, Pacific, and Australian fisheries to quantify shark interactions and operational impacts. Blue sharks dominate bycatch in many regions, while species- and area-specific variability is considerable. A large proportion of sharks are hauled alive, yet depredation damages target catch and gear, imposing costs on fleets. Finning restrictions in several jurisdictions have reduced retained shark mortality, though catch limits remain uncommon. Promising mitigation measures include chemical, magnetic, electropositive, and electrical deterrents, shorter soak times, and fleet communication to avoid hotspots.