Are there any 'old fashioned' cod in captivity or maybe stored DNA samples? Maybe Collosal could splice the missing genes back in and bring them back into the gene pool.
My take away from this is that letting the small fish go under the premise that they are juveniles that will later grow to be bigger lets the adult midgets go, ruining the gene pool. I wonder if this finding will have any impact on conservation rules against taking small fish when fishing.
What's impressive is that somebody, somewhere keeps collecting a nice stash of Eastern Baltic cod otoliths in hopes that somebody else would come along and invent a new way to use them.
I've often made the argument that evolution can happen very quickly within a few generations and doesn't necessarily take millions of years. It's interesting to see some cases in nature where rapid changes in a predator's behavior (in this case humans) can radically alter a visible trait.
I'm sure I read somewhere that Maori fishermen used to eat small-mid sized fish and left the largest ones because they were the best breeders. I can't find a reference now but has logic.
In most fish, larger size = more eggs or more sperm. So yes, largest ones are typically the best breeders. IIRC some species like I think some tuna they don't harvest the largest on purpose.
Reminds me of a line that Philip Glass co-opted for his 5th Symphony:
“Therefore the land mourns, and all who dwell in it languish, and also the beasts of the field and the birds of the heavens, and even the fish of the sea are taken away.”
I don't like how this is worded. Makes it sound as though the cod are actively reducing their size. But this is very straight forward Darwin's Theory, survival of the fittest, in action. In this case, the "fittest" cod are the ones with the propensity to be small, since they can escape the nets and survive to breed and pass on that propensity.
And it follows that there won't be a "bounce back" of the larger cod any time soon, as it takes thousands of years in a minimally interrupted state for such diversity to come about in nature. Of course this applies to all other living creatures as well.
We need to make certain parts of the world- unfishable- as in drag-net destroying pylons on the sea-floor, the waters mined with drones that attack any boat entering with the intent to fish. Its the only thing working against the international lawlessness picking the planet clean.
This is why I'm afraid of mosquitoes. Fighting them means creating a superhuman (super mosquito?) version that will be resistant to everything. When they find new diseases to obliterate the human race with, we are done.
Personally, I believe that mosquitos are far more concerning than any other impending environmental disaster.
Technology and memes spread faster than genes. Mosquitoes adapting that fast is not an issue that serious. Additionally, if hundreds of thousands of Americans died of malaria each year, we would have found much more effective cures (consider that there are already very effective ones that simply aren't widely used), just like we did with Covid.
The other thing about the Baltic Sea is that there has been so much fertiliser and toxic farming chemicals running into it since the start of the agricultural revolution that the fish is full of heavy metals and toxins. The Swedish authorities recommend against eating it more than once a month and never for pregnant women and people with health conditions.
This farming runoff overload has also led to huge areas where the sea floor is completely dead.
Crabs in the Chesapeake Bay are the same. About 80% of tidal segments there are contaminated with PCB's and heavy metals. Regulators describe them as "impairments", and recommend not eating them more than once per month. Cod are bottom feeders and are affected by pollution that settles to the bottom.
What I've had heard so far about cod's troubles in the Baltic sea is that it's not salty enough for them. For cod to reproduce, their eggs need a certain salinity so that they swim to the right depth after they are spawned.
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[ 2.9 ms ] story [ 55.6 ms ] threadPertains to Eastern Baltic cod, not all
You will see males evolve to resemble females more closely, though.
It might sound like a boring topic, but it's one of the best books I've read and something I recommend a lot.
Hail the great anthropocene.
“Therefore the land mourns, and all who dwell in it languish, and also the beasts of the field and the birds of the heavens, and even the fish of the sea are taken away.”
And it follows that there won't be a "bounce back" of the larger cod any time soon, as it takes thousands of years in a minimally interrupted state for such diversity to come about in nature. Of course this applies to all other living creatures as well.
Personally, I believe that mosquitos are far more concerning than any other impending environmental disaster.
This farming runoff overload has also led to huge areas where the sea floor is completely dead.
https://www.nationalgeographic.com/animals/article/wildlife-...
Here's an article in Latvian news site about it - https://nra.lv/neatkariga/intervijas/481931-mencu-zveja-balt...