Thursday , February 25 2021

RUSSELL WANGERSKY: Science that One Should not Surprise Contributors Opinion



Sometimes I discourage.

It is discouraged because, trapped to do things in the same way we always have, we continue to do it, even if we need to know better.

The source of my last discouragement? Last week's announcement that fishing scientists are seeing a change in some of the Atlantic Crab snow crab stocks. Scientists have found that male crabs have stopped growing: over 80% of stocks in some zones are now too small to catch.

The problem? Fishing for snow crabs targets large crabs and they disappear, leaving only small crabs behind. What did we think would happen?

Crabs that would normally be too small to win pairing fights are now the right size.

Enter a concept known as "unnatural choice," where an external force imposes a new order on organic selection.

The first I wrote about this year, 1996, for a weekly newspaper called The Sunday Express, when I mentioned a scientific study on how to successfully spawn male Dungeness crabs in British Columbia. Keep in mind that it was 22 years ago.

I've been watching since then. Here is what I wrote when I returned to the same subject on Agios Ioannos' telegram in 2001.

"Fifteen years ago, scientists working in British Columbia did some exciting research on the Dungeness crab, suggesting that if the fishing industry only took the largest male crabs, this could have some effect on the species as a whole. older males out of the picture, smaller males who could lose pairing battles had the opportunity to unite and transmit their genetic material.

"They did not all agree with the survey, but most agreed with two points: that the little male Dungeness crab seems to mate more often and that smaller and smaller crabs seem to become sexually mature.

"Not only that, they are paired, a large percentage of the smaller males stop growing and never reach commercial size, but on the genetic front, like Energizer Bunny, the pygmy crabs continue to go and go.

"In the large, evolutionary world of the Dungeness crab, the smaller ones could suddenly be better, which would be great news if you are already a small male Dungeness crab.

"It's an interesting proposition for Newfoundland's fishing, since we have harvested only the big men of snow crab species, and fishing for snow crabs is so much bigger than what remains of our fishing industry."

The thing is, we have known for decades that the fishing of fine large males deforms the species.

Fast forward so far and federal fisheries scientists say they hope that the big male crabs will return – if left alone to grow – and that change is, at this point, occasional rather than genetic. In other words, if enough big crabs are still around to give them an opportunity to survive and share, they restore the natural order.

It does not always work that way. In the Caribbean, fishing for large niches has changed the entire genetic history of the species. Coral from 7,000 years ago had 66 percent more meat in them, but, as the Smithsonian Tropical Research Institute scientist found in 2014, "Because of the persistent harvesting of larger niches, it has been beneficial for the animal to mature to a smaller size, resulting in evolutionary change. "

Scientists from Woods Hole found similar changes to cod, salmon and cod: when targeting large fish, smaller variants become more successful and transmit their genetic features, including their smaller size.

The thing is, we have known for decades that the fishing of fine large males deforms the species.

But there was a lot of money. Snow Crabs are an important and valuable fishing in New Scotland, the Prince Edward Island, New Brunswick and New Gutland and Labrador

So of course we did it anyway.

Dazzling, indeed.

The column of Russell Wangersky appears on 36 SaltWire newspapers and websites in Atlantic Canada. It can be reached at [email protected] – Twitter: @wangersky.

Related story:

There are not enough large males in Newfoundland snow crab stocks: researchers

Recently column by this author:

Time and tide are not waiting


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