Alaska-crabs Image Credit: Bloomberg

In recent years, billions of snow crabs have disappeared from the ocean around Alaska due to warmer ocean temperatures which likely caused them to starve to death, as per scientists, CNN reported.

The finding comes just days after the Alaska Department of Fish and Game announced that the snow crab harvest season was cancelled for the second year in a row, citing the overwhelming number of crabs missing from the typically frigid, treacherous waters of the Bering Sea.

The study published on Thursday by scientists at the National Oceanic and Atmospheric Administration found a significant link between recent marine heat waves in the eastern Bering Sea and the sudden disappearance of the snow crabs that began showing up in surveys in 2021.

The study's lead author and fishery biologist at NOAA Cody Szuwalski said: "When I received the 2021 data from the survey for the first time, my mind was just blown. Everybody was just kind of hoping and praying that was an error in the survey and that next year you would see more crabs."

"And then in 2022, it was more of a resignation that this is going to be a long road," Szuwalski told CNN.

The US snow crab fishery was closed in Alaska in 2022. Catchers attributed the population decline to overfishing, but "overfished" is a technical definition that triggers conservation measures, experts told CNN -- it doesn't actually explain the collapse.

Szuwalski said: "The big take home for me from the paper, and just the whole experience in general, is that historically, fishery scientists had been very worried about overfishing -- this has been our white whale, and in a lot of places we really solved that with management. But climate change is really throwing a wrench into our plans, our models and our management systems."

Scientists analyzed what could have triggered the disappearance of the snow crabs beginning in 2020 and boiled it down to two categories: the snow crabs either moved or died.

Szuwalski said they looked north of the Bering Sea, west toward Russian waters and even into deeper levels of the oceans, and "ultimately concluded that it was unlikely that the crabs moved, and that the mortality event is probably a big driver."

The scientists found that warmer temperatures and population density were significantly linked to higher mortality rates among mature crabs. The reason behind the mortality event was hungrier crabs, as per CNN.

Snow crabs are cold-water species and found overwhelmingly in areas where water temperatures are below two degrees Celsius, though they can function in waters up to 12 degrees Celsius, according to the study. Warmer ocean water likely wreaked havoc on the crabs' metabolism and increased their caloric needs.