Lessons from seabird conservation in Alaskan longline fisheries

Abstract

Although bycatch of seabirds and other long‐lived species is a critical conservation issue in world fisheries, case studies documenting significant reductions in the mortality of these low‐productivity species in a fishery are rare. We studied progress toward seabird conservation in the Alaskan longline fisheries, one of the largest and most diverse demersal fisheries. We generated annual seabird bycatch rates in 4 target fisheries and all fisheries combined from 23 years of fisheries observer data. We used 0‐inflated negative binomial models to evaluate variables influencing seabird bycatch per unit effort (BPUE) in 2 target fisheries. Following adoption of streamer lines, at first voluntarily and then mandatorily, seabird BPUE was reduced by 77–90%, preventing mortality of thousands of birds per year. Despite this, BPUE increased significantly in 2 of 4 target fisheries since streamer lines were adopted. Although night setting yielded significant reductions (74–97%) in seabird BPUE and significant increases (7–11%) in fish catch per unit effort over daytime setting, nighttime setting increased the BPUE of Northern Fulmar () by 40% and nontarget fish species by 5–17%. Thus, best practices to prevent seabird mortalities in longline fisheries varied by species assemblage and fishery. Our results inform global efforts toward fisheries bycatch reduction by illustrating that successful conservation requires fishery‐specific solutions, strong industry support, constant vigilance in analysis and reporting observer data, and ongoing outreach to fleets, especially to vessels with anomalously high BPUE.

Across borders: External factors and prior behaviour influence North Pacific albatross associations with fishing vessels

“…We found that for STAL, associations occurred slightly more frequently during the day and occurred less frequently during twilight and night. This diel pattern may help explain why albatrosses bycatch is greatly reduced at night (Melvin et al, 2019).…”

“…In the Hawai'i-based deep-set longline fishery, vessel attendance by black-footed albatrosses Phoebastria nigripes positively correlates with bycatch (Wren et al, 2019). There are a number of vesselbased mitigation options implemented for reducing albatrosses bycatch including streamer lines, night setting and dyed bait (Gilman et al, 2007;Melvin et al, 2019). Development of recommendations that reduce vessel attendance could increase compliance by reducing the burden on fishers.…”

Future Directions in Conservation Research on Petrels and Shearwaters

“…Third, the adoption of mitigation measures requires raising awareness and building trust among fishermen to develop the most appropriate solution on a case-bycase basis. Developing toolkits of proven measures, from which fishermen choose the most appropriate combination for them, could be the most direct path to reduction of petrel mortality in world fisheries (Melvin et al, 2019).…”

Ocean Optimism: Moving Beyond the Obituaries in Marine Conservation

“…Bycatch has particularly devastating consequences for air-breathing marine megafauna, in some cases being the single biggest threat to individual species (Lewison et al 2014). Methods to reduce bycatch include deterrents such as pingers and scaring lines to reduce interactions, modified timing of fishing, weakened gear designed to allow animals to break free, ropeless gear, and exclusion devices (Hamilton & Baker 2019, Melvin et al 2019). The results have been mixed and may be highly location and fishery specific, and implementation can be hampered by resistance from fishers who fear reducing their catches or increasing their costs.…”

“…Nevertheless, there are some notable successes. For example, in the Alaskan long-line fishery, deployment of bird-scaring lines resulted in a 78% reduction in seabird bycatch; the effort was notable for the careful research and coordination with stakeholders that preceded implementation (Melvin et al 2019). Similarly, use of turtle excluder devices in Australian trawl fisheries reduced sea turtle bycatch by 90% (Lewison et al 2014).…”