The news: Officials in Alaska have canceled the state’s fall king crab and winter snow crab fishery seasons after summer surveys showed a sharp drop the crustaceans’ populations. Though there may be several causes to the declining crab numbers, climate change has clearly played a role.
The context: The news is a major blow to the state’s fishing industry. The crab fisheries — including the king crabs featured on the “Deadliest Catch” reality show — normally bring in more than $200 million a year, according to the Bering Sea Fisheries Research Foundation. While the king crab has been declining for years now, snow crabs were plentiful as recently as summer 2018, making this summer’s survey findings all the more shocking.
Ecology: Rising temperatures reshape food webs
The collapsing crab populations can be traced to 2019, when record warm temperatures in the Bering Sea followed a season of drastically diminished sea ice. There was a substantially reduced “cold pool” in the region — a blob of water only just above freezing (less than 2 degrees Celsius, or around 36 degrees Fahrenheit) that rises about 100 feet from the sea floor.
The cold pool is crucial for snow crabs. Its smaller size could have played a role in declining populations in particular of juvenile crabs, which prefer colder water. A 2020 study of the crashing crab populations suggested that the “dramatic declines” may have been due to direct impacts of warmer water on development of the juveniles.
There is also the potential that indirect effects of the temperature change played a role. In general, the cold water around the snow crabs’ habitat acted as a sort of natural barrier against predators. With the warm spell in 2019, that barrier essentially collapsed. “Climate changes are opening avenues for increased predation pressure on snow crab,” said National Oceanic and Atmospheric Administration fisheries biologist Erin Fidewa, in 2020. “In the [northern Bering Sea], we have a new predator — Pacific cod — that has never been there before.”
Economics: Another blow to an industry in decline
News of the cancellation has spurred fears that many smaller commercial fishers will be forced out of business; some may be able to switch to fishing for different species. The Alaskan crab fishery fleet is already substantially diminished — in 2020, a record low of 67 vessels were operating, down from 118 as recently as 2016 and 91 vessels in 2019, according to a report from NOAA. At the turn of this century, there were 277.
Those vessels provided jobs for just under 1,000 people — also the lowest number on record for these fisheries. “We have third-generation fishermen who are going to go out of business,” Jamie Goen, executive director of the Alaska Bering Sea Crabbers, told the Seattle Times recently.
And it’s not just the vessel crews at risk. In 2020, there were seven active processing plants for Alaskan crab, another part of the industry that has undergone a long-term decline; there were 19 active plants in 2006.
The canceled seasons will have ripple effects in the state as well. For example, some small towns rely on the crab industry for tax revenue. St. Paul, a tiny Aleutian island town, will lose almost half its city budget thanks to the collapsing snow crab population.
Overall, Alaska’s crab fisheries brought in $270 million in wholesale revenue in 2020; this year, that is bound to take a hit.
Policy: How the crab quota system works
Alaska’s crab fisheries are managed under a system known as the Bering Sea and Aleutian Islands Crab Rationalization Program. Driven by the late Alaska Sen. Ted Stevens, the program was implemented in 2005; it allocates the available crabs among crab fishers, processors and various coastal communities.
Within the parameters of this federally implemented system, Alaska then relies on surveys of crab populations to set catch limits — or cancel a season entirely, in the worst of scenarios. The latest survey, released in early September, found that across all crab species there was an 11 percent increase in total the mass of mature males, which are the target of the fisheries. But that increase was over a record low in 2021, and certain species did not fare so well.
Mature male snow crabs declined by 22 percent since 2021; mature females fell by 33 percent. The glimmer of hope here, though, is that the survey found substantial increases in immature, or juvenile, male and female snow crabs; these aren’t fit for harvest but could mean better years are ahead. For now, the Seattle Times reported that Alaska’s Department of Fish and Game decided that even a small harvest this year would put the overall population at risk. “Management of Bering Sea snow crab must now focus on conservation and rebuilding given the conditions of the stock,” the department said.
Snow crab in warming waters (NOAA Fisheries)
Conservation concerns cancel Bering snow, king crab seasons (Seattle Times)
Crab fisheries explainer (Bering Sea Fisheries Research Foundation)
Thanks to Lillian Barkley for copy editing this article.