Study on the catch, bycatch and discard of Chinese pelagic longline fisheries in the Atlantic Ocean

Catch, bycatch and discard information is important for the assessment and management of fisheries. Using Chinese pelagic tuna longline observer data from 2010 to 2018, we studied the catch composition in the Chinese pelagic tuna longline fisheries in Atlantic targeting bigeye tuna (Thunnus obesus) and bluefin tuna (Thunnus thynnus), and analyzed the survival status and discard rates of common bycatch species. A total of 55 species, including tunas, billfishes, sharks, sea turtles, cetaceans, seabirds, and other pelagic species, were observed. The results indicated that the catch composition of the Chinese pelagic tuna longline fishery targeting bigeye tuna was significantly different from that targeting bluefin tuna. The annual discard rates of common species decreased over this period. Discard rate by length and discard mortality for common species were varied among species. This is the first study to estimate catch, bycatch, and discard using Chinese pelagic tuna longline observer data in the Atlantic Ocean, which is important for the management of Chinese tuna longline fisheries in Atlantic Ocean.