Unraveling the Enigma: The Astonishing Truth Behind Alaska's Vanishing Crab Population

Warmer ocean temperatures have caused a significant decline in the population of snow crabs in the waters around Alaska. This discovery follows the recent cancellation of the snow crab harvest season for the second consecutive year by the Alaska Department of Fish and Game, in response to the alarming absence of crabs in the usually icy and hazardous Bering Sea.

The National Oceanic and Atmospheric Administration published a study on Thursday that revealed a strong correlation between marine heat waves in the eastern Bering Sea and the abrupt disappearance of snow crabs. Surveys conducted in 2021 first observed this alarming trend, leaving lead author Cody Szuwalski, a fishery biologist at NOAA, astonished. "When I received the 2021 data from the survey for the first time, my mind was just blown," Szuwalski recalled. "Everyone was hoping and praying it was just a survey error and that there would be an increase in crab populations next year."

On Monday, the water level at the Rio Negro river in Manaus, Brazil reached its lowest point in at least 121 years, causing boats to become stranded at David's Marina in Brazil's Amazon rainforest. The alarming sight serves as a stark reminder of the impact of this unprecedented event. This photograph captures the scene, taken by REUTERS/Bruno Kelly.

Bruno Kelly/Reuters

Amazon rivers fall to lowest levels in 121 years amid a severe drought

"And in 2022, there was a sense of acceptance that this would be a prolonged journey," Szuwalski informed CNN. It was during this year that the snow crab fishery in Alaska witnessed its initial closure. While catchers have associated the decline in population with overfishing, experts clarified to CNN that the term "overfished" merely delineates a technical classification that prompts conservation efforts, but fails to clarify the actual cause of the collapse.

The main takeaway for me from the paper and the overall experience is that fishery scientists have long been concerned about overfishing, which has been a major challenge to tackle. However, with effective management strategies, we have successfully addressed this issue in many areas. Unfortunately, climate change has now become a significant obstacle, disrupting our plans, models, and management systems.

In the study, researchers examined the potential reasons behind the disappearance of snow crabs starting in 2020 and narrowed it down to two possibilities: either the snow crabs migrated or died.

Szuwalski conducted extensive research, exploring various regions such as the northern part of the Bering Sea, the western area encompassing Russian waters, and even delving into the deeper layers of the oceans. The team ultimately reached a conclusion that the crabs were unlikely to have migrated, indicating that the mortality event possibly played a significant role.

A California Academy of Sciences in San Francisco is currently showcasing a display featuring an ivory-billed woodpecker specimen. New footage and images claiming to capture the presence of ivory-billed woodpeckers in a Louisiana forest have been released by researchers. The government officials have announced that they will reach a final determination on the extinction status of these birds by the close of the year.

The ivory-billed woodpecker will not be listed as extinctfor now

They found that warmer temperatures and population density were significantly linked to higher mortality rates among mature crabs.

The cause of the increase in deaths: crabs experiencing hunger.

Snow crabs are typically found in cold-water regions where water temperatures are usually below 2 degrees Celsius. However, they are capable of surviving in waters with temperatures up to 12 degrees Celsius. In this study, it was revealed that warmer ocean water negatively impacted the crabs' metabolism and caused them to require more calories.

The caloric demand of snow crabs may have quadrupled in 2018, the first year of a two-year marine heat wave in the region, as researchers have found. However, with the heat wave disturbing the food web in the Bering Sea, these crabs faced difficulties in finding food and were unable to meet their increased energy requirements.

Scientists believe the crabs likely starved to death. Fish like Pacific cod likely swooped into the warmer water to feed on what was left.

NOAA Fisheries

During the heat wave, the Pacific cod were able to exploit the dire situation by venturing into warmer waters, which are typically inaccessible to them due to the temperature barrier in the ocean. Kerim Aydin, a co-author of the study and fisheries research biologist with NOAAs Alaska Fisheries Science Center, revealed that the Pacific cod took advantage of this opportunity to consume a portion of the remaining crab population.

The image provided above depicts aerial view of dredging operations underway to construct an underwater sill, located in Plaquemines Parish, Louisiana. The photo captures the city of New Orleans in the background, taken on September 26, 2023. Notably, the anticipated progress of salt water intrusion from the Gulf of Mexico into the Mississippi River has proven to be slower than predicted, as confirmed by authorities on Thursday, October 5th. Consequently, water utilities in the greater New Orleans area, relying on the river as a source of drinking water, now have several additional weeks to make necessary preparations.

Gerald Herbert/AP

The toxic, corrosive reason saltwater intrusion would be a catastrophe for New Orleans

"This had a significant impact as a heat wave," Aydin stated to CNN. "The heat wave caused widespread hunger. It's possible that other species took advantage of the situation, but now that the heat wave is over, things may be returning to normal, although the crabs still face many challenges even in regular circumstances."

Scientists have documented that temperatures in the Arctic have risen four times faster than the global average. The loss of sea ice in the region, especially in Alaska's Bering Sea, due to climate change has contributed to the acceleration of global warming.

"2018 and 2019 witnessed an unprecedented occurrence of sea ice in the Bering Sea, unlike anything we had seen before," noted Szuwalski. "The ice coverage was perhaps only 4% of what we have traditionally observed, making it challenging to determine if this trend will persist in the future."

According to Szuwalski, the situation with Alaskas crabs serves as evidence that the climate crisis is rapidly intensifying and impacting people's livelihoods. While he anticipated such consequences at some stage, he "did not anticipate them occurring this quickly."

He stated that the sudden shift in their populations was rather unexpected. However, he believes that in the long run, the snow crab population will migrate northward as the ice retreats. Consequently, the eastern Bering Sea is likely to observe a decline in the presence of snow crabs.