A new analysis estimates that longline fisheries are still decimating seabirds, even after years of efforts to mitigate deaths. According to a study in Endangered Species Research around 300,000 seabirds are drowned by longline fisheries as bycatch. Attracted by bait on the longline—sometimes measuring hundreds of miles as it trails on the surface behind a boat—birds are often hooked and drowned.
“It is little wonder that so many of the affected seabird species are threatened with extinction – their slow rate of reproduction is simply incapable of compensating for losses on the scale this study has demonstrated,” Orea Anderson, with the Royal Society for the Protection of Birds (RSPB) and lead author of the study, said in a press release.
Single longline fleets are in some cases killing tens of thousands of seabirds every year, according to the study. Fifty thousand birds, mostly shearwaters and fulmars, are estimated to have been killed by the worst offender: the Spanish longline fleet on the Gran Sol. Second in line is the Japanese tuna fleet, which kills over 20,000 birds, many of them albatrosses. Currently over 75 percent of albatross species are threatened with extinction.
Even now researchers lack data on many fishing regions, which makes estimates difficult.
Regulations have proven effective in saving seabirds. Seabird mortality rates dropped 99 percent in South Georgia and 85 percent off of South Africa with enforced regulations. Bycatch of Hawaiian fleets has also been reduced substantially through enforcement of basic mitigation techniques.
“Using simple bird-scaring lines and weighting of hooks as they enter the water could dramatically reduce the number of seabirds being killed,” Cleo Small, co-author, said.
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