Why Ten Billion Snow Crabs Disappeared Off the Coast of Alaska
smithsonianmag.com
smithsonianmag.com
I agree with my friend who studies this stuff - they dissolved from an abrupt acidity change down there
Seems like we don't actually know who is fishing in/near these waters, according to the article...
The alaskan snow crab market is in the hundreds of thousands to a few million. If 10 billion snow crabs were caught, the snow crab price would have cratered to a penny and we'd all be feasting on cheap snow crabs every night.
So according to the smithmag article, there was a 2018 population boom, unrelated to increased temperatures. That same year there was a dieoff leaving little evidence behind, but that was definitely caused by increased temperatures.
Looking at the newscientist article (https://www.newscientist.com/article/2398608-warm-seas-blame...) that Smithsonian sourced from, things are somehow even less clear:
“From 2017 to 2018, the calories they needed quadrupled.”
Between 2018 and 2021, the population fell by 10 billion, or around 90 per cent. “That’s the lowest levels we’ve ever seen them,” says Szuwalski.
The beginning of the drastic drop coincided with a marine heatwave in the Bering Sea during 2018 and 2019.
So, in other words, before the "heatwave" the crabs needed 4x calories?
Then looking at the original science paper, https://www.science.org/doi/10.1126/science.adf6035 it looks pretty clear it was actually caused by complications of a population boom and standard dieoff that occurs.
Look at a similar example we all learned in elementary school. When there is a mast crop of acorns, more animals such as squirrels, deer, and mice will survive that year and breed. In turn, the predators will have more to eat that year and increase their population as well. The overabundant prey species will eventually be starved and numbers will be decimated below the carrying capacity of the land due to a combination of starvation and over predation. The following year, predators will die off. Then the prey population will rebuild. If prey is in a rebuild cycle when a mast crop happens, effects will be multiplied.
Another example would be when multiple large cicada broods overlap and overwhelm an ecosystem with abundant food.
My overall point is that although the original paper was interesting, the evidence could have supported other conclusions other than the one that they settled on.
All the polyanna "Sometimes other things look like this! Maybe this is just normal!" isn't going to change the fact that our Earth is in dangerous violent disruption. We can expect the future to hold mostly collapse scenarios from here on.
Creatures adapt to an ecological niche, often a very particular one. Water depth, current temperature, sand composition, mineral concentrations. Tide strength, water salinity. Many other things.
There's some give, some range where the creature can continue to thrive or even do better. But go too far over on any of those bell-curves, the creature is under stress. Particularly where reproduction is concerned.
The result of changes occurring for decades can be, sudden die-off when their operating parameters are finally exceeded. When their eggs don't stick to the surface they're supposed to stick to, or their embryo won't get past a certain point in development without another degree of water temperature.
Or just, something else got wiped out, something microscopic perhaps that we don't see and don't measure and now they have nothing to eat.
Never mind snow crabs. Coral reefs are particularly sensitive to light levels, water depth, current temperature, salinity. You raise the water level by inches, coral grows on continental shelves that slant, now the coral could survive if it was 100 feet closer to shore (or further away, whatever). But it's not there, it doesn't have legs, it dies.
Sure a new one will grow in the new optimal space 100 feet over (if the water doesn't keep rising anyway). But that take about like a century. In the meantime, all those creatures that depended utterly on that reef for survival for whatever reason, be it reproduction or camouflage or food or shelter, they die off catastropically.
Ultimately the human beings that depend on the ocean for their livelihood or food source, well if you are a rich westerner you just move or get a different job. But if you're a poor peasant scratching out a living on a shoreline, you just starve.
Does that matter? How many people are we talking about? 100's of millions.
So dismiss climate change, easy from an armchair in Idaho or wherever. But don't insult the intelligence of the rest of us with naive ideas about how silly and unwarranted the concerns are. Better to keep quiet. Or learn something, anything about how biology and the environment all works together and try to make legitimate informed contributions to the conversation.
That's my rant, my advice. I know most folks will just put up their ego shields, ignore anything that doesn't jibe with their guesses and wishes and continue to slander folks who do have some idea. That's another tragedy of all this: like a 12-step program, denial is an early stage. Eventually everybody will get through that, get through all the stages and come to understand the predicament our world is in. But we don't have time to do that nicely, let folks come around in their own time. Things are falling apart too fast, and maybe gaining momentum. There is some urgency to this.
So my best advice is, be still and let the grownups talk, if you don't have any real education in all this.
https://www.bbc.com/future/article/20220809-how-the-mediterr...
The crabs that we fish today are a snapshot of the past. Very bad reproductive season this year?, you will not notice it until a few years in the future when the crabs that you expect to fish aren't there.
The year of interest is not 2018 or 2019, is (2019 - x) where x is "age of crabs reaching commercial size"
Edit: from the article: "If ocean temperatures continue to rise because of human-caused climate change, however, the overall makeup of species living in the Bering Sea will likely look very different than it does today, the researchers write." No idea why I'm being downvoted.
The absolute best investment we can make is one where we are less dependent on cars. Invest in public transportation and ban city traffic from urban areas.