New research published on Tuesday, Sept. 7, in the Journal of Marine Science and Engineering links the ongoing steep decline of northern fur seals in Alaska’s Pribilof Islands to competition for Alaska Pollock.
The harvest of Bering Sea Pollock, with the annual allowable catch set at 4.4 billion pounds, has an annual dollar value of nearly half a billion dollars. It is the largest fishery in the United States and the second largest in the world.
While the fishery remains robust, the Pribilof northern fur seal population in the eastern Bering Sea has declined by 70% since the 1970s. Competition between commercial fisheries and the fur seals for Pollock has been suspected as a contributing factor, but until now no correlative relationship between fishing activities and fur seal population decline has been demonstrated.
The researchers say they suspect what is happening is that lactating female fur seals are dependent on locating dense schools of Pollock near the Pribilof Islands for nutrition for their pups and that the Pollock fishery is targeting these same schools of fish.
The remnants of these schools of Pollock are fragmented and dispersed by the commercial fishery, making them more difficult for fur seals to locate for sustenance to they can nurse their pups. The then inadequately fed pups are less likely to survive their initial independent residence at sea as they migrate south from the Pribilofs in the fall.
Authors of the research report say their research results imply that Pollock catches at the current rate in this area may continue to suppress first year survival rates of Priblof fur seals, leading to continuing decline of this population.
“There should be a way to manage the Pollock fishery and fur seal habitat so that it does not impact the fur seals,” said Jon Warrenchuk, senior scientist and campaign manager at Oceana, based in Juneau, and one of the authors of the study.
Federal fisheries managers are working on the fur seal recovery plan, which has not been updated for a long time, he said, adding that there’s a lot of new science related to the decline of this population, and meanwhile these fur seals are heading toward endangered status.
While Alaska Pollock is harvested over a wide area of the Eastern Bering Sea, the fur seals don’t have as much of a choice on where they hunt for food, because they have to come back to the islands to feed their pups, Warrenchuk explained.
Other authors of the report, all retired government fisheries biologists, include lead author Jeffrey Short, of JWS Consulting in Juneau; Hal Geiger of St Hubert Research Group in Juneau, and Lowell Fritz, of Lynnwood, Washington.