We noted in September that because green crabs are not popular, their spread is blamed on climate change though they don’t actually like warm water much. But someone asked us why people don’t just toss them into the pot since, generally speaking, crab is a delicacy. So we checked and discovered that green crabs actually are regarded as a delicacy by some (for instance in “green crab & monkfish ceviche”) and others are promoting ways we can learn to chew our way dutifully out of the infestation. But when it comes to the snow crab, well, it’s a long-established delicacy and thus climate change is killing it. There’s a surprise.
Something called “The Daily Upside” brings the following rather distinctly downbeat story: “In 2018, the Bering Sea’s snow crab population was 8 billion. Today that figure is just 1 billion. Scientists believe the collapse is a result of water warming.” Scientists. But hang on, all you white coats. How much has the water warmed in four years?
Some of us still dimly remember from high school the elementary biology lesson about sequential boom-and-bust cycles among, most famously, rabbits and foxes. When both are scarce, rabbits proliferate like, well, rabbits. But as the amount of hopping fox food surges, more and more foxy mothers are able to raise more and more kits to maturity, whereupon the rabbits get gobbled down. And then alas there are more cute furry foxes than cute furry fox meals, and their population crashes. Rinse and repeat.
The lesson is that wild populations tend not to be stable. Not every species is as prone to the extremes as rabbits, perhaps. But it seems nothing can dent the population of stories drawing dubious links between anything bad and climate change. (A Google search of “snow crabs climate change” brought 22.7 million hits in 0.71 seconds.) Hence the New York Times snaps its claws with “Alaska is the fastest warming state in the United States, according to Climate Central, an independent group of scientists who research and report about changing climate. And rising temperatures in Alaska’s cold waters may be killing the crustaceans.” As well as causing green crabs native to the Baltic to proliferate like bad news stories.
All the cool kids are into it. The L.A. Times says “Climate change likely culprit in Alaska snow crab collapse”. It then admits that there were crabs galore in 2018 and then they vanished, and quotes someone saying that they don’t know what it was but it was climate change. (““We’re still trying to figure it out, but certainly there’s very clear signs of the role of climate change in the collapse,” said Michael Litzow, shellfish assessment program manager at the National Oceanic and Atmospheric Administration, which runs an annual survey of Bering Sea snow crab numbers.”)
As it would be regardless. Thus the story goes on that there’s also trouble in the Bristol Bay red king crab population but “the Bristol Bay red king crabs have been in steady decline for years. Specifically, the number of young or small crabs has been low for years and the reason is more of a mystery. ‘We really don’t know,’ Litzow said. Although it’s possible that warming ocean waters and low sea-ice cover are contributing to the declines in king crabs as well, these crustaceans are less sensitive to temperature changes than snow crabs.”
P.S. We cannot close this segment without a tip of the fisherman’s cap to Time for most lurid headline in a supposedly reputable publication: “Crustacean Decimation Due to Climate-Change-Driven Cannibalization”. Although regrettably the story itself didn’t really link the two, saying:
“Officials suggested that a combination of climate change and some kind of crustacean health crisis might be to blame – Alaska is the fastest warming state in the U.S. They posited that the warming waters of the Bering Sea forced the cold-loving crustaceans into increasingly small pockets of frigid water, leaving them more susceptible to hunger, disease, and predation. But that’s only part of the story, says Wes Jones, the Fisheries, Research, and Development Director for the Norton Sound Economic Development Corporation… According to the marine biologists he works with, the most immediate cause of snow-crab death is one that even seasoned fishermen and scientists didn’t see coming: a mass cannibalism frenzy.”
And guess what caused it? Right. Not climate change. A population boom of unprecedented proportions in the “fastest warming state in the U.S.”
Back in 2017:
“fishermen started reporting an unprecedented population explosion of juvenile snow crabs – what is called, in crabber speak, a “recruit.” The population boom continued into 2018 and 2019, creating what Jones says was the largest recruitment event on record.”
Say, what happened to climate change? But “At the time the young crabs were too small for a legal harvest - juvenile snow crabs take four to five years to mature” and evidently that many crabs meant not enough crab food so, well, they ate one another. Now to be sure there was a temperature spike but again, guess what?
“Unlike mammals, who use less energy when temperatures rise, cold-water fish and crustaceans speed up their metabolism. The faster the crabs grow and expend energy, the faster they have to replace it, says Jones. Some of the crabs may have headed north into cooler Russian waters, but most seem to have stayed put. ‘All of a sudden you had this huge number of little crabs coming up, eating themselves out of house and home,’ says Jones. ‘Then the water warmed, which meant they had to eat more.’ It was a double whammy, he says, and the results were inevitable for a hungry, omnivorous species that has run out of its usual food source: ‘They basically cannibalized each other.’”
So of course “Snow crabs are only the latest victim of climate change up in the Bering Sea area.” Even though “rising temperatures don’t necessarily lead to a steady decline into obsolescence. Just as likely it leads to unpredictable boom and bust cycles for climate change winners and losers that have unanticipated consequences for creatures up and down the food chain.” Indeed “A population explosion of sockeye salmon south of the Bering Sea, in Bristol Bay, is the likely reason for the recent collapse of Alaska’s lucrative red king crab harvest, which was also canceled this year, for the second time in a row. Meanwhile, the warming waters of the historically cold Bering Sea have opened the door for Pacific Cod, a predator of juvenile crabs of all kinds.”
We are all going to live.