Extinction of snow crabs in Alaska. A population decline of 10 billion!

Wyginięcie krabów śnieżnych

The extinction of snow crabs in Alaska has become the subject of detailed scientific studies. The decline in the number of individuals is alarming, to say the least. The region, known for its biodiversity and rich marine ecosystems, has faced a dramatic decline in crab populations, raising concerns about ecological stability and local economies dependent on fishing. Experts estimate that in just a few years, between 2018 and 2021, there have been some deaths. 10 billion, bringing the population to a critically low level unprecedented in previous observations.

Snow crab extinction – latest study

Initially, scientists could only speculate on the reasons for such a drastic reduction in the number of individuals. However, all speculation was put to rest following the publication of a groundbreaking new study in the journal Science on October 20. Evidence gathered by scientists at the National Oceanic and Atmospheric Administration (NOAA) indicates that the alarmingly intense heat waves that hit the Bering Sea area had a key impact on the mass extinction of many marine species. Among the most decimated have just been snow crabs, which, it turns out, have fallen victim not only to the direct effects of rising temperatures, but also to the indirect consequences of climate change. Extreme conditions have contributed to a significant reduction in food availability, condemning these animals to starvation. The extinction of snow crabs appears to be the consequence of multiple, interconnecting factors.

Extinction of snow crabs – analysis of causes

A team of researchers has attempted to understand this phenomenon, focusing on the time after 2020. The analysis assumed two main hypotheses: either the crabs migrated to new locations, or they died en masse. Szuwalski, who led the study with his team, used advanced computer models to conduct a detailed analysis of the temperature-related data. This methodology, combined with population studies, catch statistics and experiments conducted under laboratory conditions, aimed to identify factors that may have caused the extinction of snow crabs.

Cody Szuwalski shared insights into the process: “We explored various possibilities – we looked at the northern regions of the Bering Sea, towards the west, towards Russian waters and deep into the ocean,” he explained. After a thorough analysis of all the data, the researchers came to a disturbing conclusion. Szuwalski added, “In the end, we concluded that the possibility of crab migration is unlikely. All indications are that increased mortality is responsible for the observed decline in these crustaceans.”

Such a conclusion sheds new light on the situation. It seems that it is not natural migration or the search for better living conditions, but an alarming increase in mortality, probably caused by external factors, that is driving the snow crabs to extinction. According to the researchers, rising temperatures and a greater concentration of individuals in specific areas have had a significant impact on the increasing mortality rate among adult crabs. Conclusions from the study indicate that snow crabs are organisms that prefer cold aquatic environments, occurring in regions where water temperatures do not exceed 2°C. However, they have been found to be able to survive in water temperatures as low as 12°C. Warmer ocean waters have most likely had a negative impact on the crabs’ metabolic processes, while also causing an increase in their energy needs.

Snow crab extinction – could starvation have been the cause of death?

The higher water temperature probably did not kill the crabs directly. Instead, the crustaceans may have starved to death, according to Szuwalski.

Scientific findings indicate that since 2018, the start of a two-year period of unusually high temperatures in the marine region, snow crabs’ energy requirements for food may have increased by up to four times compared to previous years. Nevertheless, the extreme heat has had a destabilizing effect on most links in the Bering Sea food chain, causing snow crabs to face serious difficulties in obtaining food, unable to meet their basic energy needs.

This dramatic situation has created an opportunity for other species to take advantage of the crisis, according to the study’s co-author, biologist Kerim Aydin of the Alaska Fisheries Science Center. Typically, there is a natural temperature barrier in the marine ecosystem that keeps some species, such as Pacific cod, from entering the extremely cold habitats typical of crabs. During the heat anomaly, Pacific cod were able to move to areas where the water was warmer than usual and settled there, consuming a significant portion of the remaining crab population.

Impact of climate change on Alaska’s ecosystems

Scientists are warning that the rate of temperature increase in the Arctic is four times faster than in the rest of the world. This intense climate change has contributed to a drastic reduction in Arctic sea ice. This is particularly noticeable in the Bering Sea in Alaska, further exacerbating global warming trends.

According to Szuwalski, the extinction of snow crabs in Alaska is concrete evidence that the climate crisis is gaining momentum, threatening local livelihoods. He was aware that it would happen someday, but “did not think it would happen so soon.” The extinction of snow crabs is a warning that cannot be ignored.

“It was an unpredictable, sudden drop in their population,” he said. However, looking at the long term, snow crabs can be expected to start migrating northward in response to melting ice, which means we are likely to see them much less frequently in the eastern Bering Sea.”

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