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Bycatch of pelagic seabird species in longline fisheries is recognized as one of the most important and pervasive sources of mortality, contributing to an increased risk of their extinction. Uptake of mitigation measures to reduce seabird bycatch has not been widespread by the industry. Here, we present the results of 18 at-sea trials conducted between 2011–2015 onboard pelagic longliners targeting tuna (Thunnus spp) and swordfish (Xiphias gladius) in South African, Brazilian and Australian waters, using a recently designed seabird bycatch mitigation device. The ‘Hookpod’ is a polycarbonate capsule that encases the point and barb of baited pelagic longline hooks to prevent seabirds from becoming hooked and drowning during line-setting operations. The assessment was based on efficacy (i.e. reducing rates of seabird bycatch without impacting target catch rate) and practicality (i.e. how the Hookpod fitted into fishing operations). We observed 59 130 experimental branchlines over 129 sets and recorded a single seabird mortality on the Hookpod branchlines compared to 24 on the control branchlines, a bycatch rate of 0.04 birds/1000 hooks and 0.8 birds/1000 hooks, respectively. No difference in catch rate of target fish species between Hookpod and control treatments was detected. These findings demonstrate that Hookpods do not negatively affect catch rate of target species and could make an important contribution to halting the decline of many seabird populations if adopted as a mitigation measure by the pelagic longline fishing industry.

The population of wandering albatrosses Diomedea exulans at South Georgia is decreasing because of bycatch in longline fisheries. Until at least the early 1990s, the survival rate of females was lower than males, consistent with the adult female-biased bycatch reported for fisheries operating around the Brazil-Falklands Confluence (BFC). Here we use extensive tracking data (1990–2012) from breeding birds at South Georgia to investigate overlap with longline fishing effort reported to the International Commission for the Conservation of Atlantic Tunas (ICCAT). Using data from multiple years, we conclude that breeding females are at higher risk than males from all the main pelagic longline fleets in the south-west Atlantic. Our overlap index (based on fishing effort and bird distributions) correlated positively with numbers of ringed birds reported dead on longliners, indicating that the metric was a good proxy of bycatch risk. The consistent sex bias in overlap across years, and the likely resulting sex-biased mortality, could account for lower adult female survival rate at the colony. The risk from fisheries changed seasonally; both sexes overlapped with pelagic longline effort during incubation (January–March), and particularly during post-brood chick-rearing (May–December), whereas overlap was negligible during brooding (April). The highest percentage of overlap was with the Taiwanese fleet, then vessels flagged to Brazil, Uruguay, Spain, Japan and Portugal. Females were consistently at greatest risk in the BFC region, whereas males showed lower and more variable levels of overlap with fisheries from 35 to 45°S. Our results have important implications for management of ICCAT longline fisheries and conservation of this highly threatened albatross population.