Research On International Management For Mitigation Of Seabird Bycatch By Tuna Longline Fishery

As the most abundant tuna stocks in the three oceans(Atlantic,Indian Ocean and Pacific Ocean),the catch from the Pacific Ocean accounts for more than 70% of the world’s total tuna production,of which 80 percent of tuna production result from catch managed by the Western and Central Pacific Fisheries Commission(WCPFC).As classified by fishing gear,the tuna catch by longline fisheries accounts for 10-13 per cent of the total production in the WCPFC Convention Area,however its value is comparable to that of purse-seine fisheries.If they intend to feed on baited hooks in longline fisheries,seabirds get hooked or entangled and drown when the hooks sinks to the fishing depth.In terms of the type of gear,longline fishing gear is a type of fishing gear that is susceptible to catching seabirds,and with the increase of bycatch mortality by longline fishery interaction with the number of seabird species(especially albatrosses and petrels),the impact of fishing on these species stock should be reduced as necessary.The bycatch of seabirds could also have an adverse impact on fishing productivity and profits.Therefore,governments,Regional Fisheries Management Organization(RFMO)require that conservation measures should urgently be taken in order to reduce amount of seabird bycatch and mortality by longline fisheries,which may mitigate the effect of seabirds stocks.The first Chapter analyzes the catch of tuna fisheries and catch by tuna longline fisheries in WCPFC Convention Area.The chapter also elaborate and analyze the amount of seabird bycatch by WCPFC’s member tuna fleet,which mitigation measures are subsequently taken.The second chapter using observer data obtained from the WCPFC database,it is noted that 31 species of seabirds occur in the bycatch by tuna longline fishery during2010-2019.The most amount of bycatch seabird species are black-backed albatross,the black-footed albatross,New Zealand albatross,white-jawed shearwater,White-capped albatross and Kansage albatross,which were incidentally caught to be 1299,982,762,626,246,245 and 118 individuals,respectively.In addition,939 unidentified-genus albatross are recorded.It is noted that Kansage albatross is considered to be endangered,the rest are considered to be near or vulnerable species,of which shy albatross and Kansage albatross are reported to be the highest bycatch mortality rate.The seabird bycatch is affected by a variety of factors.GAM model is constructed and the influence of spatiotemporal and environmental factors on the bycatch rate is analyzed by using the abundance index data of seabird bycatch obtained by observers from the Western and Central Pacific Fisheries Commission as well as the environmental data.Among all factors,longitude contributed the most,followed by Chl-a,latitude and SST,with contribution rates of 36.9%,5%,4% and 3.3%,respectively,and the F test showed that all model factors were correlated with BPUE.Chapter 3 presents development of conservation and management measures adopted by WCPFC for seabird bycatch mitigation.Four types of seabird bycatch mitigation are listed and compared.Setting operation and applied fields are also presented for above four type mitigation.The chapter summarizes the fishing efforts,observation hooks and observed seabird bycatch in WCPFC members in 2019,and applied mitigation measures are compared.Data from National Fishery Report I are compared to analyze the impact and feasibility of different mitigation measures on reducing seabird bycatch.Chapter 4 analyzes the spatial distribution of Chinese longline fisheries in the WCPFC Convention Area and the current situation of seabird bycatch.It is noted that government and industry actively comply with conservation and management measures to reduce seabird bycatch.China’s efforts to mitigate seabird bycatch are analyzed and the experience and issues are summarized and suggested in longline fishery practice.Chapter 5 puts forward the problems and prospects confronted by reducing seabird bycatch in longline fisheries,and suggests on the conservation and management for seabirds.Suggestions are made on that not only seabird bycatch release is necessary to be taken,but also seabird bycatch prevention should be highlighted.It is also noted that fishermen training should be conducted in order to improve seabird conservation consciousness of fishery operators as much as possible,and increase the knowledge popularization of mitigating seabird bycatch and technical training in the use of mitigation measures,and call on relevant fishery management authority and industry to actively comply and enforce conservation and management measures,which may improve our image for responsible tuna fishery.