Scientists estimated over 10 billion of the snow crabs disappearing from Eastern Bering Sea between 2018 to 2021, the industry’s stakeholders and fisheries researchers had various theories about where they’d gone.
Many believed that it was due to disease, bycatch cannibalism, bycatch, or crab fishing, whereas others believed it was predation by sea animals such as Pacific cod.
However, researchers say they’ve identified the most likely reason of disappearance. The cause is a sea heatwave in the period between 2018 and According to a recent study that was authored by a team of scientists at the National Oceanic and Atmospheric Administration.
Mike Litzow is a co-author of the study as well as the director of NOAA’s Kodiak laboratory. He claimed that starvation caused by higher temperatures led to the collapse.
“Really the crabs weren’t in a position to obtain the nutrition they needed,” Litzow said. “They were simply over-consuming the resources readily available.”
As per Litzow and his co-workers The crab had to contend with many factors that compounded The first was that warmer temperatures meant a higher metabolism which meant they required more food in addition to this there was less room for the crab to hunt for the food they needed; and lastly the crabs were smaller than the normal.
Researchers gathered data from numerous theories that could explain the disappearance of the species and analyzed it in conjunction with the information they have about the decline. They looked at the possibility of mortality from a variety of sources, including direct fishing in the industry of snow crabs and bitter crab syndrome, the most fatal of crustaceans caused due to parasites and the trawl’s bycatch.
“The take-home message is that none of the other possible mechanisms can explain the reason for the decline in the information we have,” Litzow said.
He added that it’s hard to understand what the decline caused by increased ocean temperatures might be for other species however, it’s safe to predict that we’ll experience more of these heatwaves in the ocean similar to this one and are likely to get bigger and more frequent because the planet continues to warm.
“As we’re seeing these huge, shocking collapses there’s a general understanding of the need to construct the capacity to handle more of them,” he said. “We require systems that will be able to withstand these huge, shocking incidents.”
A higher concentration of carbon dioxide in the atmosphere will lead to warmer temperatures, Litzow stated this is negative for the snow crab that loves cold weather. In addition, more greenhouse gases means more acidic oceans which could be hazardous for certain crab species.
“Carbon dioxide that is released by fossil-fuels also gets absorbed by oceans and can result in decreasing the pH in the oceans — which makes it more acidic” Litzow explained. “Because crabs use calcium carbonate for their exoskeletons, they’re susceptible to acidification since calcium carbonate disintegrates rapidly when pH drops.”
The positive aspect -, at the very least in snow crabs that they aren’t as affected by ocean acidification as other species.
“In our laboratory in Kodiak we’ve conducted various studies over time looking at various crab species at various ages, life-history stages as far as how susceptible the species is to acidification” said Dr. Xiaoping. “And the good news is that it appears that snow crab is one of the species that are more resilient -in the sense that we don’t notice an impact as strong on snow crab in the same way we do with red king crab, or like we see in the case of the Tanner crab.”
The Alaskan snow crab fishery is closed since 2022 after authorities declared that the population was overfished..
The crash of the snow crab in conjunction with the two-year shutdown to Bristol Bay red king crab was a huge blow to the thriving crab fishery in Alaska and also left some fishermen and coastal communities, like St. Paul Island, looking for alternative sources of income.
The bigger picture remains pretty grim crabs have been decreasing in Alaska since the mid 1980s Litzow added that there’s still plenty of cool water flowing through Alaska’s oceans and, with it, optimism for spindly crustaceans.
“Snow crabs have been bouncing across the board,” he said. “Historically there’s been fluctuations and ups — and there’s previously been overfished declarations. We’re sure to be optimistic as we’re seeing small crabs appearing in the survey in 2022 and 2023.”
However, Litzow said, the rebound could take a while.
“If conditions are stable over the next four years, then we can anticipate this crab to increase enough to that they will be able to sustain the fishery,” he said.
The snow crab saga has affected Alaska’s fishing industry, and further similar incidents are probably in the near future in the opinion of Litzow. He noted that the more dependent communities or fisherman are dependent on one particular fishing venture, the more vulnerable they are.
While diversification could be among the best and most efficient strategies to deal with these shocking crash, Litzow said it’s also likely to be one of the most difficult.
“We use a system of management in which everybody has access to the system to the system. It’s all allocated according to a specific way or everyone is equipped with equipment, vessels specially designed for this kind of fishery” he explained. “And when these unexpected events and interruptions occur it’s not easy to provide backup plans.”
As with other research, Litzow said this study doesn’t provide the ultimate answer, but that it’s an important first step.
“It is a fantastic job of defining what we can expect,” he said. “We shouldn’t expect the crabs simply disappeared elsewhere, perhaps down the Slope or even up in Russia or anything similar to that. This study clarifies that they perished and provides our most complete explanation for how it happened.”
