- In October 2022, the National Oceanic and Atmospheric Administration (NOAA) announced that the lucrative snow crab fishery in the Bering Sea would close for the first time, following a population decline of 80% between 2018 and 2022.
- While fisheries managers and biologists say climate change is to blame for the species’ retreat, some fishers and crab experts suggest that trawling bycatch and other fishing activity may have played a role in the snow crab’s decline.
- The fishery’s closure has amplified a chorus of concerns about Alaska’s trawling industry and the knowledge gaps around its potential impact on fisheries.
The disappearance of billions snow crabs from the Bering Sea has captivated the world’s attention since Alaska shut down the fishery for the first time in October 2022. But where exactly did these snow crabs go? And what caused them to vanish so quickly?
Scientists are still grappling with these questions, but climate change is the most cited hypothesis for the species’ retreat. Erin Fedewa, a research fisheries biologist at the National Oceanic and Atmospheric Administration (NOAA), said the decline of the species, Chionoecetes opilio, coincided with a marine heat wave that swept through the Bering Sea between 2018 and 2019, which possibly caused the species to experience starvation, increased disease or predation.
Some fishers and crab experts put forward a different idea: They’ve suggested that fishing, particularly the unintentional capture of crabs in fishing gear known as trawls, also contributed to the loss of the snow crab, or at the very least, impeded the species’ recovery from low population levels.
The snow crab fishery’s closure has amplified a chorus of concerns around Alaska’s trawling industry — mainly from within the fishery sector itself — and the knowledge gaps around its potential impact on fisheries.
‘A big shock’
Jamie Goen, executive director of the Alaska Bering Sea Crabbers, a nonprofit trade organization, said this year’s shutdown of the snow crab fishery, which is worth up to $200 million in annual revenue, has been “devastating” for crab fishers.
She said that while she anticipated the shutdown of the red king crab (Paralithodes camtschaticus) fishery in Bristol Bay this year and last year due to the population’s gradual decline, the snow crab fishery closure was “a big shock.”
Not so long ago, things looked different for snow crabs. In 2018, Bob Foy, the science and research director of NOAA’s Alaska Fisheries Science Center, an institution that collects data on marine resources to help ensure the sustainable use of stocks, reported that a survey had “documented one of the largest snow crab recruitment events biologists have ever seen.” (Recruitment is the addition of individuals to a species’ population.)
News of this “record high” led many fishers to invest financially in the upcoming crab seasons, Goen said.
“They made investments and took out loans with banks, and now everything’s collapsed, and those banks still want their payments,” Goen said. “I think some companies are going to go out of business and go bankrupt and have to sell their boats.”
Fedewa, who has been conducting bottom trawl surveys of snow crabs for four years as a fisheries biologist at NOAA, said she and other scientists observed a decline between 2019 and 2021, but that no one expected the population to drop further in 2022.
“We thought this stock had hit rock bottom in 2021,” Fedewa said, “but the larger individuals — mature females and the large males — actually declined even more from 2021 to 2022.”
The NOAA survey showed the snow crab population had dropped from 11.7 billion in 2018 to 1.9 billion in 2022, a decrease of about 80%.
Fedewa said the overlap of the snow crab decline and the marine heat wave — when average bottom temperatures increased from 1.5° Celsius (34.7° Fahrenheit) in 2017 to 3.5°C (38.3°F) in 2018 and 3.3°C (37.9°F) in 2019 — “points to temperature and broader human-attributed climate change as a major factor.”
Warmer temperatures are thought to substantially impact snow crabs because they rely on “cold pools” under the sea ice to take refuge from predators. But a 2020 study led by Fedewa found that during warmer years, these cold pools constricted in size, providing less space for the species to take shelter.
“When you have a lot of crab and a small amount of space, you start to be concerned about density-dependent processes, like predation, disease, starvation, and those are key hypotheses that could potentially explain this decline,” Fedewa said.
Data collected by the University of Southern California also showed snow crabs shifting their distribution, migrating north toward the Bering Strait over the past four decades.
Ray Hilborn, a marine biologist and fisheries scientist at the University of Washington, agrees with the theory that the marine heat wave led to the snow crab decline.
“When something like this happens, I say, ‘What’s different?’” Hilborn told Mongabay. In this case, he said, what changed was the marine heat wave, which may have led the snow crabs to starve.
“We had this big period of warmth and a very high recruitment of snow crab,” he said. “And the physiological calculations suggest that the metabolism of the crabs [was] about twice as high with that warmer water [and scientists make] the case that they basically ran out of food.”
‘It all happens under the water’
But not everyone shares that opinion. David Bayes, an Alaskan fisher and a moderator of STOP Alaskan Trawler Bycatch, a public Facebook group with more than 20,000 followers that has become a forum for Alaskan fishers concerned with trawling, said that while he’s sure climate change played a role in the disappearance of the snow crabs, he believes that trawling is also responsible.
“Alaskan fishermen are typically pretty tight-knit, and nobody wants to speak up against somebody that fishes in a different industry,” Bayes told Mongabay. “There’s this fear that if we shine this light on trawl that it risks shutting down all the fisheries. And so for decades, that’s kept the lid on, essentially from the people on the inside. But now it’s gotten to the point where other fisheries are being shut down, and we’re worried about the habitat under the water, and there’s climate change added to it, and the ups and downs have become more drastic and unpredictable.”
Besides the potential impacts on the snow crab, Alaskan fishers and politicians have expressed concern about trawling bycatch of red king crab, Chinook salmon (Oncorhynchus tshawytscha) and halibut (Hippoglossus stenolepis). Mary Peltola, who was sworn in as Alaska’s first Indigenous member of Congress in September 2022, recently tweeted that bycatch from industrial trawlers not only harms populations of fish, crabs and mammals, but affects “ecosystems outright by altering the balance of species in the water.”
In April 2022, the North Pacific Fishery Management Council (NPFMC), the organization that advises the state of Alaska on trawling bycatch limits, revealed in a paper that pelagic trawls, which are meant to pull a funnel-shaped net through the midwater column in pursuit mainly of pollock (Gadus chalcogrammus), actually spent anywhere from 40-100% of the time dragging their nets on the bottom.
Bayes called this a “bombshell piece of information,” since pelagic trawlers are allowed to fish in places where bottom trawlers aren’t, including a closed area in the Bering Sea that was set up to protect crabs.
“When these midwater nets hit bottom, they have this cable or chain that just drags on the bottom, so the probability that it’s hitting crab and everything else is higher,” Bayes said. The crabs likely wouldn’t be caught in the midwater nets, but could be killed and left in the ocean, he said. This is considered “unobserved bycatch,” for which there is no current limitation.
“It all happens under the water, which is out of the public eye and tough to quantify, but at some point, common sense begins to play a role,” he said.
On the other hand, limits for observed snow crab bycatch that is hauled up on deck are set on the annual estimates of abundance, ranging from 4.35 million animals to 13 million animals. If the set limit is exceeded, trawling is shut down for the season. For 2022, fisheries managers reduced the limit from 7.1 million snow crabs to 4.35 million due to low abundance of the species, according to NOAA and the NPFMC.
While 4.35 million snow crabs might still seem like a lot, Fedewa said that trawling bycatch has contributed very little to the decline of the species. For instance, in 2020, she said the total bycatch biomass contributed to about 0.03% of the total decline.
Yet Erik Velsko, a fisher from Homer, Alaska, who served on the advisory panel for the NPFMC between 2019 and 2021, underscored an additional issue: snow crab bycatch is only counted if it is caught within certain areas known as C. opilio bycatch limitation zones (COBLZ).
Velsko called this “archaic fisheries management” that is “not responsive to changing ocean conditions that could be causing crab stock biomass to shift from historic grounds.”
Fedewa said the COBLZ zone “encompasses almost the entirety of the snow crab range,” but added that NOAA is currently conducting research to better understand the species’ movements.
‘Why aren’t we looking at impacts’ from trawling?
Bayes said he believes trawling impacts on snow crabs are not being fully investigated due to conflicts of interest within the NPFMC, the group responsible for setting trawl catch and bycatch limits. He alleged that most of the 11 voting members of the NPFMC have ties to the trawling industry and that some are even positioned to “gain financially by keeping the trawl fleet fishing,” which results in decisions biased toward trawling.
Velsko told Mongabay he observed close ties between the fisheries management agencies, industries, and even research institutions during his time serving on the NPFMC advisory panel. He added that models used for fisheries management have “too many assumptions” built into them to be fully accurate, and that knowledge gaps around trawling impacts are not being filled.
“I wouldn’t put the decline [of snow crabs] solely on the shoulders of the trawlers, but why aren’t we looking at impacts from them at all? Why are we not even entertaining that at all? It just seems bizarre to me,” Velsko said.
David Witherell, executive director of the NPFMC, denied these claims, saying in a statement to Mongabay that “any notion that the Council is dominated by trawling interests is simply incorrect. Only one of 11 voting members represents the trawl sector.” He further cited conflict-of-interest rules preventing members from voting on issues in which they have “significant financial interests” and pointed out that the trawl industry should have a place on the council since “90% of the groundfish (by weight) are caught with trawl gear in the North Pacific.”
Goen of the Alaska Bering Sea Crabbers, an organization that has been asking for additional protections for snow crabs from trawling, said that while she doesn’t think trawling is directly responsible for the collapse of the snow crabs, she does believe it played a role in “inhibiting these crabs from rebuilding back to levels that we can fish on” as the population declined in recent years.
Like Bayes, Goen said she was concerned about pelagic trawlers fishing on the seafloor in areas closed to bottom trawling. Additionally, she said that trawlers can operate during the crabs’ molting and mating season, when crabs could be particularly vulnerable to trawling — a practice banned in Canada and Russia.
Goen added that officials have not generated any new restrictions on trawling to protect snow crabs during the fishery’s closure, which she called a “shortcoming.”
Carter Braxton Dew, a former NOAA fisheries biologist who worked for the agency for 25 years, agreed that climate change probably isn’t solely responsible for the snow crab’s disappearance.
“During the past few years, as the numbers of some major Bering Sea crab stocks have approached the vanishing point, climate change and ocean warming have received most of the blame in the news media,” Dew told Mongabay in an emailed statement. “Overfishing and trawl bycatch have gotten relatively little attention.”
In 2021, Dew filed a formal complaint against NOAA via Public Employees for Environmental Responsibility (PEER), an organization that supports whistleblowers who call attention to illegal or improper government actions. The complaint argued that “suspect” data had led to exaggerated annual population estimates of red king crab in Bristol Bay, which resulted in overfishing and the eventual collapse of the population.
NOAA, however, said in a recent statement that a “combination of factors … related to continued warming and variability in ocean conditions in Alaska” likely affected the red king crab, but did not suggest that mismanagement or overfishing played a part.
‘Everybody wants to blame trawling’
Hilborn of the University of Washington rejected the suggestion that trawling is to blame for the disappearance of the snow crabs.
“Everybody wants to blame trawling for everything,” he said. “And again, nothing has really changed there. The trawl fisheries have been going on for a long time.”
Fedewa said that overfishing and trawl bycatch may have some impact on snow crabs, but that any potential effects could not “explain the scale of the decline that we’ve seen in the snow crab population.”
“But I will acknowledge that we obviously need more research to understand the potential implications of gear and our actions with crab and potential mortality,” she added.
When asked if this research was already taking place, Fedewa deferred to Sarah Marrinan, a fisheries economist at the NPFMC. Marrinan said in an emailed statement conveyed through Fedewa that the amount of crab bycatch from trawl fisheries in the Bering Sea and Aleutian Islands that comes on deck was “pretty low.” However, Marrinan added there is “interest in additional research on and accounting for unobserved mortality of crab … from bottom and mid-water trawl vessels as well as impacts on benthic habitat.”
While experts continue to investigate and debate the collapse of the snow crabs, all are united in the hope that the species will recover.
“The scientists are telling us there’s a small signal of recruitment, so a small sign of new crab coming into the fishery,” Goen said. “But we’ve got to do everything we can to protect them, and it would be three to five years before they’d be a fishable size.”
Velsko said he believes a solution lies in NOAA conducting a comprehensive study to put a real number on unobserved mortality and using this number to inform regulations. He also recommended that the NPFMC count all snow crab bycatch beyond set zones. Without such measures to protect snow crabs and other commercially fished species, he said he fears for the region’s future.
“Alaska is always heralded as the shining example of fisheries management,” Velsko said, “but I think it was just because it was the last place to be exploited. We’re getting to that point where we’re going start seeing problems like this occur all the time until we get things straightened out, or until the whole thing comes crashing down.”
Correction (11/08/2022): A previous version of this article incorrectly stated that pelagic trawlers could fish in closed area around the Pribilof Islands, but pelagic trawling is actually banned there. Pelagic trawlers can, however, fish in other closed areas in the Bering Sea.
Elizabeth Claire Alberts is a staff writer for Mongabay. Follow her on Twitter @ECAlberts.
Related listening from Mongabay’s podcast: Goldman Environmental Prize winner Claire Nouvian discusses the impacts and policies on trawling, listen here:
Fedewa, E. J., Jackson, T. M., Richar, J. I., Gardner, J. L., & Litzow, M. A. (2020). Recent shifts in northern Bering Sea snow crab (Chionoecetes opilio) size structure and the potential role of climate-mediated range contraction. Deep Sea Research Part II: Topical Studies in Oceanography, 181-182, 104878. doi:10.1016/j.dsr2.2020.104878
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