A snow crab, at top, is displayed with a bairdi tanner crab, at bottom, in this undated photo. The crab species are related, but snow crab generally dwell in farther-north and colder waters. State officials are allowing a bigger snow crab harvest than last year's very small allowable catch. But an unprecedented spike in the number of snow-tanner crab hybrids is affecting the rules for the upcoming harvest. (Photo provided by National Oceanic and Atmospheric Administration's Alaska Fisheries Science Center)
Snow crab stocks in Alaska’s Bering Sea, which crashed a few years ago, have recovered enough to allow a modest harvest starting in mid-October.
The Alaska Department of Fish and Game on Monday announced that fishers will be allowed to harvest 9.3 million pounds of Bering Sea snow crab from Oct. 15 to May. The harvest cap is about twice the 4.72 million pounds allowed in the past season, which followed an unprecedented two-year period of closed harvests.
The Bering Sea snow crab harvest closures came after catastrophic losses that scientists have attributed to an intense, multiyear marine heatwave that started in 2018.
The 9.3-million-pound total harvest cap set for the coming season is much smaller than past harvests that, at their peak, reached hundreds of millions of pounds in the early 1990s.
The harvest cap was set by the state based on biological parameters approved by the North Pacific Fishery Management Council. Bering Sea crab harvests are co-managed by the state and federal governments.
The Department of Fish and Game on Monday also announced a Bristol Bay red king crab harvest cap of 2.68 million pounds, up slightly from the 2.31-million-pound allowable catch set last year. The red king crab harvest will run from Oct. 15 to Jan. 15, the department said.
Like snow crab, Bristol Bay red king crab, known for their huge size and the high market prices they fetch, suffered a recent crash. Harvests were closed from 2021 to 2023; it was the first two-year stretch without a Bristol Bay red king crab harvest.
There will also be an increase allowed in the harvest of Bering Sea tanner crab, a species related to snow crab but less sensitive to heat. The department on Monday announced a combined 11.25-million-pound harvest cap spread across western and eastern areas of the Bering Sea. That is nearly twice the allowable Bering Sea tanner crab catch the department set last year.
The increased harvest limits follow scientific surveys that found increases among all three types of crab typically harvested in the Bering Sea.
“It’s getting better. It’s a slow and steady increase here,” Katie Palof, an Alaska Department of Fish and Game researcher, told the North Pacific Fishery Management Council on Monday.
Palof is part of the state-federal team studying and monitoring Bering Sea crab; she presented survey findings on Monday without any of her National Oceanic and Atmospheric Administration colleagues because of the federal government shutdown.
For harvesters, the signs are welcome, said Cory Lescher of Alaska Bering Sea Crabbers, an industry group of independent harvesters.
“As crab harvesters and industry, we’re really encouraged by the positive signals that we saw come out of the bottom trawl survey with regards to crab, particularly for snow crab,” Lescher told the council. “We’re still concerned that all the stocks are low, but we’re seeing at least a step in the right direction with some of these results that we saw.”
There is a twist to this year’s snow crab harvest: 1 million of the allowable catch is to be composed of snow-tanner crab hybrids.
That is due to a boom in such hybrid species.
In the past, such hybrids have existed in varying but relatively small numbers. When harvested, they were usually counted as snow crab, Palof said. Up to now, hybrids were considered too insignificant to be counted in the harvest recommendations or limits.
But this year, scientists conducting Bering Sea snow and tanner crab surveys found that about 20% of the males that were big enough to be harvested – about 4 inches across – were hybrids, Palof said.
“This is unprecedented,” she said.
Exactly why the hybrid boom happened is unclear, but it coincides with the recent collapse in the snow crab population and the past year’s delayed maturation of female snow crab, Palof said.
In the future, fishery managers want to learn more about the snow-tanner hybrids, she said. If hybrids continue to be important parts of the total Bering Sea crab population, there may be a need to formally include them in stock and harvest calculations, she said.
While short-term signs are encouraging, there are signs of potential long-term problems.
For Bristol Bay red king crab, there have been no jumps in the population of immature crabs since 2015, Palof said. That raises concerns about future population sizes, she said.
“While we’re seeing a steady slow increase in biomass, we’re not expecting to see any large increases in biomass without recruitment,” she said, referring to the growth of juvenile fish into adulthood.
There are concerning signs for king crab in the Bristol Bay marine environment as well, Palof said. More wind meant poorer feeding conditions for larvae, she said. Waters were warmer than in the past four years, and there are continued corrosive conditions at depth with lower pH levels that affect shell growth.
For snow crab and tanner crab, there are concerns about the shrinking size of adult males, as the industry prefers to harvest big adult male crabs. Unlike king crab and some other shellfish species, which continue growing and replacing their shells throughout their lifetimes, snow crab and tanner crab have limits to their growth.
“Once they molt to maturity, they stop growing,” Palof said.
Also for snow crab, there is a continuing threat of new marine heatwaves like the 2018-2019 event that scientists blame for the recent crash.
A new marine heatwave has developed in the North Pacific off the coast of California. Though that has not extended north of the Aleutian Islands, sea surface temperatures in the Bering Sea are well above normal as of Monday, according to NOAA.
Mark Stichert, the Alaska Department of Fish and Game’s Kodiak-based groundfish and shellfish management coordinator, said the possibility of future heatwaves could factor into future harvest decisions.
“Most of the climate projections suggest that these blobs of warming, marine heatwaves, they’re more likely to occur more often,” he said on Friday. That leaves managers with the question of how to account for factors like this that are out of their control, he said.
“We do know that snow crab, as their name implies, like cold water. Absences of cold water, their stock does not do well,” he said.
