SEATTLE — A Bering Sea survey by federal scientists contains more bad news for Alaska, Washington and Oregon-based crabbers hoping for an upturn in upcoming harvests that last year fell to rock-bottom levels.
The federal survey results for Bristol Bay king crab are bleak and crabbers have been warned that — for a second consecutive year — there may not be a fall harvest, according to Jamie Goen, executive director of the Alaska Bering Sea Crabbers.
The new survey results, released late last week, show that the population of mature male snow crab targeted by crabbers decreased by 22% from 2021, which at 5.6 million pounds was at the lowest level in more than 40 years. The snow crab population crashed amid a Bering Sea warming, and the new survey results are likely to result in an even smaller harvest for the upcoming winter season.
Alaska, within the limits of a federal management plan, determines how many crabs can be caught based on these surveys, as well as analysis by state and federal scientists. When more crabs are found in these surveys, the harvest levels generally climb. When the surveys indicate crab populations are in decline, the managers typically slash the quotas to give the populations a better chance to rebound. And, when the numbers fall too low, the harvests may be shut down.
As recently as 2016, the Bering Sea crab harvests grossed more than $280 million for a fleet that uses baited steel-framed traps — called pots — along the bottom of the ocean.
Snow crab and king crab historically have been the biggest-dollar harvests for Bering sea crabbers, some of whom also pursue smaller populations of other species. And the harvest cuts expected this year will put some fishermen who have big debt loads at risk of financial disaster, Goen said.
“We have got an emergency,” Goen said. “I’m trying to get Congress to act to help.”
The National Marine Fisheries Service survey does offer hope for improved harvests three to five years from now, as young snow crabs grow to adult size.
“The positive news is that we saw a significant increase in immature snow crab abundance, both males and females,” said Mike Litzow, survey lead and director of the Alaska Fisheries Science Center’s Kodiak Laboratory. “Depending on how many of these young crabs actually survive to adulthood, this could be one bright spot for the fishing industry in a few years.”
Surveys show long-term decline
The survey is conducted during the spring and summer months. It has been conducted annually since 1975, with the exception of 2020, when it was canceled due to the COVID-19 pandemic. Scientists this year worked aboard two chartered fishing boats that start in Bristol Bay and slowly move to the west. They catch crabs with nets at 375 sites ranging from 120 to 1,200 feet in depth.
The surveys have tracked a long-term decline in Bristol Bay king crab.
Though fishermen target the mature males, the harvest only goes ahead if there also are enough mature females found. In 2021, federal researchers estimated only 6.3 million mature female crabs — the lowest number in more than a quarter century. This year, the estimate increased to 7.3 million. But that was still below the minimum of 8.4 million that the Alaska Department of Fish and Game has set as the threshold to allow harvests.
Scientists say unfavorable ocean conditions appear to be working against the king crab recovery. But figuring out specifics has been difficult.
During the past decade, as the Bering Sea warmed, king crab in some years moved farther north. Researchers say one possibility is that young crabs may have lower survival rates when they mate in these waters. Another possible factor is increased predation, including from Bristol Bay sockeye salmon as their populations boomed.
Scientists also are scrutinizing the practice of catching undersized crabs and then throwing them back, which could cause death. There is also research and debate about the impact, both in decades past and currently, of trawl nets towed along the bottom by vessels pursuing cod and flatfish species, as well as larger nets deployed by pollock boats that also may hit the bottom.
One former federal biologist, Braxton Dew, in a whistleblower complaint filed in 2021 through Public Employees for Environmental Responsibility, alleges that sampling bias and data falsification during some of the surveys in the 1970s “paved the way for the collapse” by giving inflated stock estimates. Based on those surveys, fishery managers approved excessive harvest levels from which the crab populations have yet to recover.
Cooler years could help
Snow crab have a shorter life cycle than king crab, and their numbers have fluctuated greatly. Crabbers caught more than 300 million pounds of snow crab during two peak years in the early 1990s. Last year, after the population crashed, the harvest was slashed to just 5.6 million pounds.
During the Bering Sea warming of recent years, there were big reductions in winter sea ice, which is vital to the formation of a pool of cold water by the sea bottom that offers young snow crabs refuge from predators such as cod that dislike the chill temperatures.
As the cold pool shrank drastically, scientists say cod predation increased and that mortality, along with other stresses from the warmer water, may have contributed to the implosion of the snow crab population.
Researchers also are looking at other stresses from the warmer water. Crabs’ metabolism, for example, speeds up as temperatures rise, and food supplies could have been inadequate to meet their needs. So starvation may have played a role.
Even as the Bering Sea warming hurt the snow crab, salmon scientists say it likely gave a boost to Bristol Bay sockeye, which generally do better when temperatures rise a few degrees and returned this past summer in record numbers.
As the sea warmed in 2018 and 2019, the surveys indicate more of the surviving snow crabs were found farther north than in years past.
Last year, the survey results included a more than 99% drop in immature female snow crabs compared to those found just three years earlier, as well as a 96% drop in males.
This year’s survey estimated the immature female populations jumped by 3,902% — a 39-fold increase compared to 2021. The immature males were up by 138%, more than double.
Those findings suggest that if cooler temperatures continue, the snow crab harvests will increase.
But federal fishery biologists who undertake the survey caution that more warming is forecast as climate change spurred by fossil fuel combustion and other human activities release greenhouse gas pollution.
“We will get another heat wave. Whether it’s one year, or five years, it will come,” said Leah Zacher, a federal fisheries biologist based in Kodiak with the Alaska Fisheries Science Center who participated in the survey. “And the question is — what will happen?”