What killed off billions of Alaska’s snow crabs?

One billion snow crabs disappeared from the Bering Sea. No one is sure why — but climate change is suspect #1

Published October 28, 2022 12:00PM (EDT)

Freshly caught snow crabs in boxes (Buddhika Weerasinghe/Getty Images)
Freshly caught snow crabs in boxes (Buddhika Weerasinghe/Getty Images)

For the first time in recorded history, snow crab season was canceled in the Bering Sea off the coast of Alaska.

On October 10, the Alaska Department of Fish and Game and the National Marine Fisheries Service cited concerns about the reduction in the snow crab population, which numbered in the billions before their recent mysterious decimation. As the population fell by over 90 percent, the Alaska Department of Fish and Game (ADF&G)  canceled the season to allow the population to rebound in hopes that it would return to replacement levels by next year. 

The report says that NOAA does not mention overfishing and aggressive scraping of the ocean floor as a main reason behind decreasing crab numbers.

"Understanding crab fishery closures have substantial impacts on harvesters, industry, and communities, ADF&G must balance these impacts with the need for long-term conservation and sustainability of crab stocks," the official advisory says. "Management of Bering Sea snow crab must now focus on conservation and rebuilding given the condition of the stock."

But while experts know that the snow crab population has decreased tremendously, the cause is not entirely clear. But among the culprits, global climate change perhaps looms largest.

Divergent hypotheses

While the scientific community is torn on the precise cause of the Bering Sea crabs, the majority of the blame falls on global warming. Yet some think the National Oceanic and Atmospheric Administration (NOAA) — the governing body of U.S. fisheries and marine conservation efforts — played a larger role in the snow crab's disappearance than they publicized.

A whistleblower who once worked with NOAA released a report in 2021 in Public Employees for Environmental Responsibility, detailing supposed data falsification and other dishonest activities NOAA conducted. The report claims that "scientific fraud" is why the snow crab population fell to such extreme lows.

The report says that NOAA does not mention overfishing and aggressive scraping of the ocean floor (where snow crabs lay their eggs) as a main reason behind decreasing crab numbers. Instead, they "attributed the sudden loss of millions of crabs to 'a drastic increase in natural mortality' and 'massive die-offs,' claims for which no evidence ever materialized." 

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Spencer Roberts, a writer and ecologist, published a now-viral Twitter thread on the snow crab population collapse, where he questioned NOAA's reliability as a data source. "There is an institutionalized corruption problem within NOAA, in which fisheries management councils and advisory panels, who play instrumental roles in setting quotas and issuing permits, require a given proportion of their seats be occupied by representatives of the fishing industry," he writes.

Following a request for comment, NOAA referred Salon to a statement: "Stock assessments and data sources are subject to a public, transparent, and rigorous, peer-review process. External experts are an important part of the review process to ensure that the integrity of the science and management responses are appropriate and based on the best scientific information available."

The peril of warming waters

Although the alarming drop in crab population seems sudden, it has been tracked, researched and predicted for years. 

In the 2021 survey, snow crab numbers had fallen dramatically — there were just enough snow crabs to open the crabbing season that year. This year, numbers fell short of the set threshold.

The deeper ocean waters that snow crabs favor to produce offspring — waters that usually aren't frequented by predators due to the cold temperatures — are warming. This has opened the door for predators, such as the Arctic cod, to attack snow crab nursery waters. The optimal temperature range of snow crabs isn't being satisfied in this environment, which breeds disease, and worse issues. In addition, commercial crabbing ships are trawling the deep waters, causing critical damage to the snow crab's breeding grounds.

In other words, human-caused environmental change, such as warming waters, are creating ricocheting effects on marine life. Natural selection has always governed the success of some and failure of others to reproduce. When conditions are changing as fast as they are now, organisms that are well-suited to the conditions and specific microenvironment they are adapted to cannot make this change as fast as they must. As the temperature ranges in the Bering Sea shift farther and farther away from the ideal, the snow crabs are forced to adapt or die. 

Where are the crabs? (And lobster, and fish?)

Philip Loring, an ecological anthropologist whose research delves into the multi-pronged issues facing Alaskan fisheries, predicted snow crabs to be one of the first species affected by warming waters. 

"Many critics of current approaches to fisheries management have been saying it's just a matter of time before we see a high profile fishery experience dramatic changes because of climate change," he says. "If it was just climate change, in all its complexity, that doesn't absolve the fisheries management system, because we've known climate change is going to be dramatic for decades."

Alaska isn't the only fishing industry hit hard by the warming climate — it's an issue of global scale. Fisheries are essential to the international food supply. Approximately 500 million people, in some capacity rely on fisheries for their livelihoods, and in some developing nations, up to 50% of animal protein consumption comes from marine organisms.

However, human demand has far outpaced supply. According to sustainable marine systems researcher Éva Plagányi, the "wild capture fisheries yield has likely already reached its natural limits."

Yet, commercial fisheries aren't able to meet the global demand either. Facing the same warming environmental conditions and myriad of related issues, fisheries are becoming less productive. In the Bering Sea, waters are warming faster than snow crabs can adapt, and overzealous fishing boats are squandering chances of population recuperation in the Bering Sea. 

"Climate change created an opportunity for the fishing industry. In the same way that the fossil fuel and shipping industries exploit opportunities created by sea ice declines, the fishing industry does as well," Roberts says. "It's important that media report on the impacts of climate change, but we should also be wary of the way that climate change can be used to excuse or obscure the impacts of extractive industries."

By Natalie Jonas

Natalie Jonas is a writer and a former editorial intern at Salon.

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Related Topics ------------------------------------------

Alaska Climate Change Fishing Marine Life Noaa Snow Crabs