High mortality rates of Chelonia mydas in a small‐scale bottom gillnet fishery in the south‐west Atlantic Ocean

Abstract

Abstract In Brazil, five species of sea turtles use the region for feeding and reproduction. For these endangered species, one of the biggest impacts on their populations is incidental catches in fishing gear. In the state of Santa Catarina (SC) ‐ Brazil, fishing is an important economic activity, with distinct and numerous industrial and artisanal fleets. These fleets incidentally capture all five species of sea turtle. In the Canoa beach fishing community in the municipality of Barra Velha (SC), gillnet fishing holds great economic and cultural importance. The four main gillnet fisheries in this community are whitemouth croaker, leatherjacket/mackerel, hake, and grouper/catfish/flounder, the latter of which is carried out on rocky bottoms and is locally called ‘malhão’. In this fishery, fishermen have reported catching sea turtles over the years, especially the green turtle Chelonia mydas. In the present study, 1,998 sets were monitored between September 2010 and April 2011, of which 104 (5.2%) were of gillnets for whitemouth croaker Micropogonias furnieri; 324 (16.2%) were for leatherjackets Oligoplites spp. and mackerel Scomberomorus spp.; 1,261 (63.1%) were for hake Cynoscion spp.; and 309 (15.5%) were for grouper Epinephelus spp., catfish Genidens spp., and flounder Paralichthys spp. Considering all fisheries, the incidental capture of sea turtles occurred in only 3% of the monitored sets. In all, 87 sea turtles were captured, 78 (89.6%) of which were recorded in the ‘malhão’. Of these captures, 68 (87.2%) were C. mydas, eight (10.2%) were loggerhead turtle Caretta caretta and two (2.6%) were ‘hard‐shelled’ turtles. The direct mortality rate observed for C. mydas in the ‘malhão’ was 73.5%, which is the highest rate recorded in similar fisheries of the south‐west Atlantic, thus raising concern for the protection of this species in the Atlantic Ocean.