Why Did 11 Billion Alaskan Snow Crabs Suddenly Disappear A Scientist Explains the Mystery Crabs - Alaska HEAD TOPICS

Why Did 11 Billion Alaskan Snow Crabs Suddenly Disappear A Scientist Explains the Mystery

10/21/2022 12:48:00 PM

Is this the crab-pocalypse

Crabs Alaska

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Slate

Is this the crab-pocalypse Experts are still trying to understand the catastrophic population collapse that has shut down a crucial fishing industry—but they have some theories. a year. The sudden shutdown has left the state, well, shell-shocked.Experts widely agree that global warming likely played a major role in the crabs vanishment—but they are still trying to figure out the details of how. To get a sense of what may have caused this mysterious mass die-off and why the fishing and scientific communities had been taken by surprise, Slate spoke with Dr. Mike Litzow, the shellfish assessment program manager at the Alaska Fisheries Science Center for the National Oceanic and Atmospheric Administration. Litzow’s team conducts the survey that measures snow crab populations in the Bering Sea each year, which in turn helps populate the models that the state uses to set its fishing quotas. Read more:
Slate » What made billions of snow crabs disappear from the Bering Sea? Alaska Cancels Snow Crab Season After 90% Of Population Disappears Microsoft tells regulators that it wants to create an Xbox mobile app store Crypto hacks are set to hit all-time highs in 2022, analyst explains

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Silver Peak has gained newfound attention in recent years as the energy and transportation sectors race to wean themselves off climate-warming fossil fuels. Read more >> What made billions of snow crabs disappear from the Bering Sea?The Bering Sea's snow crab population has been in decline over the last five years, but this season the population has collapsed. 💔😞 andonitgoes Alaska Cancels Snow Crab Season After 90% Of Population Disappears Alaska has canceled the Bering Sea snow crab season for the first time ever due to an estimated 1 billion crabs disappearing over the last two years, the cause of which researchers are still investigating but could be linked to disease or climate change. What do you think? I had no problem catching crabs in Alaska Aerial dancer Not sure how you can call them snow crabs when they don't even live in the snow, instead loving in water. 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Bama fan? the entire snow crab harvest for the year.Snow crabs in the Bering Sea once numbered in the billions.Alerts Alaska has canceled the Bering Sea snow crab season for the first time ever due to an estimated 1 billion crabs disappearing over the last two years, the cause of which researchers are still investigating but could be linked to disease or climate change.Alan Friedman 1 When it comes to the smartphone business, Microsoft could have been a contender. The reason? Nearly 11 billion crabs had suddenly disappeared from the Bering Sea. The news heralded a catastrophic population collapse for the animals, in which nine out of ten died out between 2018 to 2021. In 2018, about 3 billion mature snow crabs (Chionoecetes opilio) inhabited the Bering Sea along with roughly five billion immature crabs, the Seattle Times reported (opens in new tab). It’s a terrible development for those who make a living harvesting the crabs in a region of the world that’s warming unusually fast because of its proximity to the North Pole. (Alaska officials also canceled the fall Bristol Bay red king crab harvest for a second year in a row.5 million and 6.) This isn’t a small industry; Alaska’s crab fishing is worth a year. Eventually, Microsoft put the kibosh on its plans to challenge iOS and Android and when Microsoft launched the Surface Duo dual-screened handset in 2020, it was powered by Android. The sudden shutdown has left the state, well, shell-shocked. In February, the National Marine Fishing Service issued an official overfishing notice (opens in new tab) for the population, and in early October, officials at the Alaska Department of Fish and Game (ADFG) made the difficult decision to cancel the season's snow crab harvest for fear of wiping out the crustaceans altogether. Advertisement Advertisement Advertisement Experts widely agree that global warming likely played a major role in the crabs vanishment—but they are still trying to figure out the details of how. To get a sense of what may have caused this mysterious mass die-off and why the fishing and scientific communities had been taken by surprise, Slate spoke with Dr. The agency also canceled the fall harvest of Bristol Bay red king crabs (Paralithodes camtschaticus), due to low survey numbers. Mike Litzow, the shellfish assessment program manager at the Alaska Fisheries Science Center for the National Oceanic and Atmospheric Administration. Litzow’s team conducts the survey that measures snow crab populations in the Bering Sea each year, which in turn helps populate the models that the state uses to set its fishing quotas."  "It came after a lot of sleepless nights and a lot of tears. Microsoft's response included these comments:"Building on Activision Blizzard’s existing communities of gamers, Xbox will seek to scale the Xbox Store to mobile, attracting gamers to a new Xbox Mobile Platform. This interview has been condensed and edited for clarity. Slate: This seems like it would have been a dramatic thing to watch unfold. Snow crabs thrive in the cold northern waters of the Bering Sea floor. When did you realize the scope of this population decline? Advertisement Advertisement Litzow: Dramatic is definitely the right word. In 2018, we observed the highest abundance of snow crab that we’ve ever seen. As seawater cools, it becomes less salty and less buoyant, causing it to sink to the bottom of the ocean. Our estimate was that there were 11. Discussing the proposed purchase of Activision Blizzard, Microsoft explains to the CMA that"The transaction gives Microsoft a meaningful presence in mobile gaming. 7 billion snow crab in the southeast Bering Sea—largely smaller animals that were about to grow large enough to harvest. Many fish and other types of marine life avoid the cold pool, but for juvenile snow crabs, it’s a sanctuary. So in 2018, things were looking better than they’ve ever looked for snow crab. Advertisement In 2019, we went out and did the survey. But lately that protection has waned. And while it was still good, suddenly, the abundance of small animals was half as good as it had been. We were concerned but not alarmed—just sort of wondering what was going on. 2 report published by NOAA (opens in new tab)." Microsoft adds that it"currently has no meaningful presence in mobile gaming and the Transaction will bring much-needed expertise in mobile game development, marketing, and advertising. In 2020, of course, COVID hit, so we didn’t go out. And then 2021, we went out, and there were 10 billion fewer animals than there had been in 2018. As anthropogenic climate change progresses over the next few decades, these types of heatwaves are projected to become more common, according to the report. So the abundance went from 11.7 billion in 2018 to 940 million in 2021. Trawling vessels targeting other marine species in the Bering Sea frequently encounter, catch and discard unwanted snow crabs as"bycatch" ” And when snow crab fishers haul a catch aboard, they toss out crabs that are deemed too small, too young, or whose shells are discolored or marred in some way. So there’s just a wholesale collapse in the population. The smallest tier of the industry, the purchase would represent a larger chunk of this market which could make the regulatory agency concerned enough to block the deal. And it was very sudden, and was not predicted. In 2020, the ADFG estimated that over 30% of all snow crabs that were captured and tossed back into the Bering Sea died as a result, the Seattle Times reported in April. Advertisement Advertisement Advertisement We went out this year, in 2022, and we got results that confirm the 2021 survey—that the crab are really gone. It’s not like they moved somewhere else. RELATED STORIES—What animals could go extinct by 2050? —What's the first species humans drove to extinction? —Mass bird die-off in eastern United States baffles scientists Crabbing is big business in Alaska. It really looks like a mass mortality event. What can we know with certainty as to what happened here? Our data show that in 2018, 2019, and 2020, the Bering Sea was just far warmer than anything we’ve seen before. "People are simply going to go bankrupt and they’re not going to be able to feed their families," Jamie Goen, executive director for Alaska Bering Sea Crabbers, told KIMA-TV (opens in new tab), a television station in Yakima, Washington. New reasons to get excited every week Get the most important news, reviews and deals in mobile tech delivered straight to your inbox Subscribe. That [change] actually began in 2016. And we know that you can’t get the Bering Sea that warm without human-caused global warming. But for now, the crabs will remain off-limits for commercial fishers. Advertisement Advertisement If we look at the core area of the snow crab range on our survey, the average temperature from 1982 to 2012 was 1.3 degrees.. In 2018, we had 3. 5 degrees. All available data really suggest this is a climate change story. Advertisement Advertisement Have we ever seen anything like this die-off before? No, the temperatures we’ve seen in the Bering Sea since 2016 have absolutely no precedent. It’s been uniquely warm. How exactly does a 2-degree temperature increase lead to the deaths of billions of crabs? It’s hard to disentangle, but there’s a few leading hypotheses. The first thing to know is that snow crab are an arctic animal. In the Bering Sea, we only find them in areas that have winter ice cover, with bottom temperatures below 2 degrees C. In this ecosystem, two [additional] degrees really takes you over an ecological threshold. If your bottom temperatures in the system are colder than 2 degrees C, it’s an arctic system. Most of the predatory ground fish that are more abundant to the south, like Pacific cod, don’t tolerate those temperatures. But then if you warm that up to 3, 3.5 degrees, it’s like flipping a switch. There are more subarctic ground fish that can come into that area. So one hypothesis is that warming waters allowed predatory ground fish into the snow crab range, and that there was a massive predation event. Advertisement Advertisement Advertisement Another hypothesis is that there were some diseases that affect this population—that when you warm them up, you get an increased incidence of those diseases. And then another hypothesis is that because you had this high abundance of crab [from the 2018 population boom] in a very small area [because they clustered in pockets of cold bottom water] with very high metabolic demand, they outstripped their available food, and there was starvation. It’s hard to disentangle those different explanations. They’re all plausible. But it appears some combination of those is the actual link between the warming and the mortality event. How exactly did you figure out that all those crabs disappeared? How did this survey work? We have 375 standardized stations across the southeast Bering Sea, which is sort of the breadbasket for all these incredibly productive fisheries. Every year, we go out and we sample these 375 spots, and we set a bottom trawl from a commercial fishing boat, which we run for half an hour. We then process the catch: identify all the fish, the crabs, sex them, measure them, collect all kinds of different biological data. And that gives us an estimate of the abundance of fish and crabs. It gives us a comparison through time of how the populations are changing. Advertisement Advertisement Advertisement So we take the survey data, we take data from the fishery, we take data from bycatch from other fisheries that capture snow crab. You take all these datasets, and they all tell a different story. So the best way to understand what’s going on is to use a mathematical model of the population that incorporates all these different datasets. How do you know the crabs didn’t simply move outside the range of your stations? When the 2021 survey had such an extreme result, maybe it just warmed up and the crabs moved was an explanation to examine. But we also have a survey in the northern Bering Sea, and so we can confirm that the crab did not move north, as you might expect. And there was a possibility discussed about the crowd moving deeper in the Bering Sea, deeper than the area that we sample. But when you look at the available habitat in deeper waters, there’s just not enough room for 10 billion crab to be there. Advertisement Advertisement Advertisement Then there was interest in whether the stock moved to Russian waters. We don’t have data from the Russian side to test that hypothesis. But the available information from the Russian side doesn’t really support the idea. Advertisement Are snow crabs uniquely vulnerable? Are there other animals we should expect to see die off as well? Snow crab are unique in that they’re by far the most economically valuable arctic species. Most Bering Sea fisheries operate on subarctic or boreal species: things like cod and pollock, or red king crab or red salmon. [ Editor’s note: The “subarctic” refers to the slightly warmer region just south of the arctic. ] And these species, you wouldn’t expect them to have such immediate negative consequences from a warming event. Some of these species have been seen in huge numbers moving up north and occupying this formally arctic habitat. So they’re not collapsing in the way snow crab have. Advertisement Did we know the degree to which snow crabs were susceptible to warming temperatures? Why did this die-off take people by surprise? People have been saying for decades that if the Bering Sea loses its sea ice, we should expect snow crab to be one of the stocks that’s most strongly affected. And we have known for decades, big picture, that the arctic is warming up more quickly than the planet as a whole. So we’ve known that big changes were coming, in sort of a general way. But there is all this sort of natural climate variability, and it’s very hard to predict what the temperature is going to be next year or the year after. We just know that in 50 years, it’s going to be much warmer than it is now. But for a population like snow crab, what really matters is this year or next year. Advertisement Advertisement Advertisement And we have seen in the Bering Sea really abrupt, really strong warming, that in some cases was a lot more rapid than what we had expected. Until recently, the oceanographers were telling us that the northern Bering Sea would be ice-covered in the winter for our lifetimes. And then in 2018 and 2019, the northern Bering Sea lost its ice cover. And so we’re seeing this switch to ice-free conditions. It just happened more quickly than the scientific community was expecting. And we’ve never seen the Bering Sea this warm before. So it’s hard to predict the exact consequences. But now that we have this observation of the system in a really warm state, it’s easier to make predictions about what we should see next time. So the next time we see such warm conditions and very low sea ice cover in the preceding winter, we know that that’s going to set up the bottom temperatures to be much warmer than normal. We’ll definitely have more of an ability to predict the response. Advertisement So what do we know about the future of the snow crab population? This year, the Bering sea temperatures have reverted to something that’s more similar to average conditions over the last 30 years. And at the same time, we’re seeing a lot of small snow crab appear in the survey this year. So there’s hope that if we get some run of colder years, and if the small snow crab are able to survive up to commercial size over the next four to five years, there might be some hope on the horizon for this fishery. Popular in .