Seasonal Abundance and Size Structure of Sharks Taken in the Pelagic Longline Fishery off Northwestern Cuba

Abstract The Straits of Florida comprise an important migratory route for apex predators moving among the Gulf of Mexico, Atlantic Ocean, and Caribbean Sea. Off Cuba’s northwestern coast, various gear types are used by Cuban fishers, including small-scale pelagic longlines. We report here the results of a 2011–2019 monitoring program for the longline fleet based in Cojímar, Cuba. This fleet comprises 134 small vessels targeting mostly swordfish (family Xiphiidae), billfishes (family Istiophoridae), tunas (family Scombridae), and sharks (class Chondrichthyes) within 20 km of Cuba’s coast. Most operations are nocturnal with 11–12-h sets comprising an average of 56 hooks on 6,643 m of mainline. Five orders, eight families, and 18 species of sharks were documented in this fishery. Two carcharhinids (Silky Shark Carcharhinus falciformis and Oceanic Whitetip Shark C. longimanus) and two lamnids (Longfin Mako Isurus paucus and Shortfin Mako I. oxyrinchus) were the most abundant shark species caught, with shark CPUE averaging 1.98 sharks/trip (SD = 0.938). Catch abundance showed seasonal differences, with Silky Sharks and Longfin Makos more common in winter and Oceanic Whitetip Sharks more common in summer and autumn. Bimodal size structure in some species suggests multiple life stages utilizing the area, while the predominance of young sharks in species including the Oceanic Whitetip Shark suggests the importance of the area as juvenile habitat, possibly as a pupping and/or nursery ground. This characterization of the Cuban longline fishery is an important step forward for Cuba’s National Plan of Action for Sharks and demonstrates the potential impacts that small-scale fisheries can have on vulnerable sharks.