Bycatch, which is the bycatch of non-target species in commercial fisheries, is not just limited to salmon, crabs, and other fish. Seabirds are also unintentionally caught and killed in fishing gear.
A recent annual report from the National Oceanic and Atmospheric Administration shows some mixed but mostly positive trends of bird bycatch in Alaskan halibut and bottomfish crops.
Overall, 4,509 birds were killed through bycatch in those fisheries in 2021, just over two-thirds of the annual average of 6,592 birds reported from 2011 to 2020, according to a report from the National Marine Fisheries Service. of the National Oceanic and Atmospheric Administration (NOAA). One potential factor in the relatively low bycatch total, the annual report said, is the decline in total fishing trips related in part to the ongoing COVID-19 pandemic. The total of 12,873 recorded trips made in these fisheries last year was lower than any annual total from 2011 to 2020. In contrast, the highest number of fishing trips in the period was 19,246 in 2016, and this was also the year with the most Seabirds were killed in bycatch in that period, approximately 10,500, according to the report.
Another factor likely to influence total seabird bycatch is the trend among sable fishers to switch from longline gear to pot gear. Longline fishing uses covers with baits lowered into the water, while pot gear is essentially a type of fish trap. Harvesters are switching to potting equipment to prevent whales from eating hooked fish, the report said, but the move has an added benefit for the birds. She said seabirds are less likely to be killed by pot gear than by entanglement in longline gear.
The report said that the incidental catch of birds is recorded by observers appointed on fishing vessels and through electronic monitoring.
A worrying sign noted in the report is the high level of bycatch among one species of bird: the shearwater.
More than half of seabird by-catch deaths in 2021 were among shearwaters. This bycatch coincided with the mortality of seabirds in 2021, which was dominated by shearwaters, and was consistent with the patterns of previous years, when the numbers of deaths and bycatch were greater.
The report said that rising ocean temperatures may have a role to play. She added, “It is believed that changing ocean conditions have depleted the shearwater’s nutritional resources, causing fishing vessels to target fishing baits more aggressively.”
Deaths of various species of seabirds have swept across the Bering Sea and Gulf of Alaska since 2015, and have been linked to warming ocean temperatures.
Bycatch of seabirds occurs mostly in longline fisheries, in contrast to bycatch of salmon and other non-target fish, which are problematic in trawl harvesting.
Bycatch of seabirds is important to fisheries management because of the risks to endangered or depleted species.
Short-tailed albatrosses, long-distance travelers that breed almost exclusively on a single Japanese island, are of particular concern. The death of a few of these endangered birds could lead to the closure of fisheries. In the early 2000s, the fishing industry began using gear modifications to prevent bycatch of albatrosses.
The NMFS report said there were no reports of short-tailed albatross deaths in the 2021 fishery. It said the two short-tailed albatross deaths in 2019 were the first such events in Alaskan waters since 2014.
About 400 albatrosses of other species died during bycatch in 2021, the report said. Those were the black-legged albatross and the Laysan albatross, which the US Fish and Wildlife Service has classified as a species of concern. The report said there were no 2,021 deaths due to bycatch of threatening Stellar pies or spectacled feasters.
The seabird bycatch report follows a report released earlier in the year that tracked deaths and serious injuries to marine mammals managed by the National Oceanic and Atmospheric Administration (NOAA). That report showed that from 2016 to 2020, sea lion entanglements in fishing gear dominated unintentional deaths of marine mammals, consistent with patterns from previous years.
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