Distribution and trends of reported observed seabird bycatch mitigation use in the WCPFC Convention Area WCPFC-SC20-2024/EB-IP-27

Under the WCPFC Conservation and Management Measure to mitigate the impact of fishing for highly migratory fish stocks on seabirds (CMM 2018-03), Members, Participating Territories and Cooperating Non-members (CCMs) are required to report on the use of seabird bycatch mitigation methods in their commercial pelagic longline fisheries in Annual Reports Part 1. For the review of WCPFC CMM 2018-03, we sourced data on reported observed bycatch mitigation use from all Annual Reports – Part 1 during 2019-2023 and relative fishing effort per CCM across the Convention Area from WCPFC. Using these two data sources, we calculated the proportion of annually reported seabird bycatch mitigation use per mitigation method per relevant latitudinal band (>30°S, 30°-25°S, 25°-20°S, 20°S-23°N, and >23°N) as a function of the number of actively fishing CCMs. Further, and based on the assumption that reported observed bycatch mitigation use is representative of total fishing effort for that flagstate, we calculated mitigation use by total relative fishing effort. Results indicate that the most frequently reported bycatch mitigation methods were weighted branch lines, followed by tori lines, and night setting (across all latitudinal bands). Whilst recognising that mitigation use in the relatively low levels of observed effort may not reflect fishery-wide practices, simple extrapolation provides some interesting insights. In the area >30°S (where 2/3 mitigation methods or hook-shielding devices are required), ≥2/3 mitigation methods were used in only 54% of fishing effort. Conversely, in 30°-25°S ≥2/3 mitigation methods were used in 69% of fishing effort, although only 1/3 mitigation methods or hookshielding devices are required. In 25°S-20°S, some form bycatch mitigation was used in 45% of fishing effort, despite the absence of requirements for this area. Contrastingly, however, in the area 20°S-23°N some form of bycatch mitigation was used in 57% of effort, even though this area is visited less by vulnerable seabirds than the area of 25°S-20°S and equally has no bycatch mitigation requirements. Few trends in reported bycatch mitigation use over time were evident, but non-reporting was increasing over time across most latitudinal bands. These results are of relevance to the review of WCPFC CMM 2018-03 as well as to future outreach and education efforts to support the implementation of seabird bycatch requirements across the WCPFC Convention Area.