The population of snow crabs within the Bering Sea off the west coastline in Alaska has fluctuated over time. A rise in the number of young crabs in 2018 prompted optimism that fishing could remain good for many future years however, this optimism was not long-lasting.
Gabriel Prout and his family are the owners of the fishing vessel Silver Spray in Kodiak, Alaska.
He stated that it was evident that something was not right in the past few years. It was clear that something had gone wrong. Bering Fishing grounds in the Sea are typically covered with sea ice during the winter months. However, there was not much ice, and the fishermen were farther north than normal. Finding snow crabs was difficult.
“It was a terrible casting,” stated Prout. “We looked endlessly for miles miles, but we didn’t find any sign of anything.”
Over 10 billion Bering Sea snow crabs went extinct in Alaska between the years of 2018 through 2022. This is damaging a fishery industry commercially of $200 million the year before. The decline in population coincided with an extreme heat wave which hit in the Bering Sea. Today, researchers and fishermen are trying to determine the cause, and they believe that warmer ocean waters could be at fault.
Bycatch, the catch of non-target species has also been criticized by fishermen for its impact on the fishing of snow crabs. Despite the fact that the fishing area is shut to crabbers, the catch limit in the trawl industry is 3.6 million snow crabs this year.
However, such a massive sudden decline in population and absence of sea ice was warning for scientists such as Erin Fedewa, a research fishery biologist at the National Oceanic and Atmospheric Administration.
“That was a very immediate smoking gun after we observed that Arctic species suddenly declining,” she said.
This is because sea ice is an essential element in snow crabs’ lives. In winter, it builds up on the surface of the water. In the summer months, the melting ice is released leaving dense, cold water down towards the ocean floor at a point where it is just above freezing about 35 degrees.
Scientists refer to it as the cold pool. it’s a refuge for the young crabs. Warmer temperatures can result in hunger and a higher rate of illness. In the Kodiak Fisheries Research Center, federal and state scientists are attempting to determine what factors led to the decline of the crabs.
Tanks that are filled with seawater that is pumped into the bay mimic situations on seafloor.
“And then, we can observe different parts of the same species in some cases, like five degrees Celsius and eight degrees Celsius. Then we can start to examine the reaction of these species after they’ve been in warmer temperature ranges,” said Fedewa.
Scientists make use of the pools to study how the pH and temperature levels affect the development of crabs -how quickly they grow and how fast they die.
“We know that rises in temperature boost metabolic rates of crabs and fish, which causes them to consume more and more food,” said Fedewa.
In a cold pool shrinking which means more crabs being pushed into smaller spaces which means less food. In the hallway across from the federal laboratory, Ben Daly, a research coordinator for the Alaskan Department of Fish and Game is trying to determine the ways that a shrinking cold pool impacts crabs in the Bering Sea.
“That’s one of the things we’re currently doing is trying to unravel the what went wrong part. It’s only half of the task. The second half of the issue is how is next?” the man said.
The team has been tracking crabs that are in the wild using satellite transponders which track their movements throughout the course of time. The tags should provide more precise information about their distribution in the freezing pool.
In March, a team of federal and state researchers set off to the Silver Spray to continue studying crab populations in the wild outside of the laboratory. Federal scientists conduct assessments of population within the Bering Sea each year during the summer.
Prior to the trip Gabriel Prout said this winter survey is a significant step towards understanding the species in general.
“We’ll be completing 20 days of pot surveys and pulling pots and measuring the crab’s size, defecating it and sizing that crab” He said.
Tagging the crabs with Daly’s transponders for satellites.
Prout as well as his entire family is extremely grateful for their efforts. Many fishermen who depend on snow crabs for their income have lots of questions rather than solutions now.
“We’re still trying to make our pennies count to figure out how we’ll move forward,” Prout said.
Researchers predict it could take a few years for the number of snow crabs recovers. If a new heatwave strikes the Bering Sea this year, it could be longer. They’re hoping that the experiences from snow crabs could provide insights into how other marine species deal with changes in climate when the ocean heats.
The story written by NOVA in collaboration with NOVA with major financial support from the Corporation for Public Broadcasting.
