Overlap between pelagic longline fisheries and Black Petrels in the WCPFC Convention Area

Black Petrels are endemic to New Zealand, exclusively breeding on two island colonies. This species is highly vulnerable to bycatch in commercial fisheries, including in commercial pelagic longlines. Bycatch of Black Petrels in New Zealand fisheries is well monitored, and estimated mortality levels place this species at a relatively high risk level. However, this species’ range extends well beyond New Zealand’s jurisdiction. Little is known about bycatch risk beyond New Zealand’s EEZ both during the breeding period when Black Petrels forage widely, and when birds migrate across the Pacific during the non-breeding period. This study aims to estimate overlap between Black Petrels and commercial pelagic longline fishing effort across the WCPFC Convention Area, as a proxy for bycatch risk. To achieve this, fine- and coarse-scale Black Petrel tracking data were combined with fishing effort data, inferred from Automatic Identification System data sourced from the Global Fishing Watch, to calculate yearround fisheries overlap in the WCPFC Convention Area. While the highest density of commercial pelagic longline overlap occurred close to New Zealand and south of 30°S, considerable overlap was evident in latitudes where fewer bycatch mitigation methods are required (30°S - 25°S) or not mandated (north of 25°S). Additionally, relative overlap of Black Petrels with commercial pelagic longline fishing effort was highest north of 25°S. Therefore, though this species spends reduced time north of 25°S in the WCPFC Convention Area, overlap with commercial pelagic longline fishing, and potential bycatch risk, is high when they do. We conclude that year-round tracking of this species has shown high overlap with bycatch-prone fisheries in areas of the WCPFC Convention Area with reduced bycatch mitigation efforts.