Thursday , January 21 2021

Russell Wengerski: A Science That Must Not Surprise Any Columnist opinion



I get discouraged sometimes.

Desperate, because, caught doing things like we always have, we keep doing them, even though we need to know more.

The source of my last laxity? Reports last weekend that fish scientists are seeing some stock change in the Atlantic and Canadian cancer stocks. Scientists have found that male prawns have stopped growing: more than 80 percent of the stock in some areas is now too small to catch.

The problem? The snow crab fishing targets large crabs, and those that disappear, leaving only small crabs behind. What did we think would happen?

This cancer was usually too small to win and mating fights are now the right size.

Enter a concept called "unnatural selection," in which external force imposes a new order in biological selection.

I first wrote about this in 1996, for a weekly newspaper called "Sunday Express," when I reported on scientific research on how to successfully breed Dungeness crabs in British Columbia were smaller and smaller. Remember, it was 22 years ago.

I've been following it ever since. Here is what I wrote when I returned to the same subject in the St. John's telegram in 2001.

"Fifteen years ago, scientists who worked in British Columbia did a fascinating study of cancer in Dungeness, suggesting that if the fishing industry takes only the biggest male crabs, it could affect the entire species. Mating, had the opportunity to mate and pass on their genetic material.

"Not everyone agreed with the study, but most agreed with two points: Little male cancer Dungeness seems to mate more often, and that smaller and smaller crayfish seem to be sexually mature.

"Not only that, as soon as they mate, a large proportion of the younger men stop growing and never reach the marketable size, but on the genetic front, like the Energie Banner, the strong crabs continue to walk, and walk away.

"In a wide-ranging evolutionary world of lung cancer, smaller can suddenly become better, and it would be good news if you've been a small cancer cancer Dungeness.

"This is an intriguing proposition for fishing in Newfoundland, since we harvest it – you have it – only the big males of the snow crab species … and the snow crab fishing is such a huge part of what is left of our fishing industry."

The thing is, we know for decades that selective fishing for large men and skews species.

Fast forward to the day, federal fishing scientists say that they hope that large male crayfish will return – if left alone grow – and that the change is, at this stage, situational rather than genetic. In other words, if enough large crayfish are still around to get a chance to survive and mate, they re-establish the natural order.

It does not always work that way. In the Caribbean, big conch fishing has changed the genetic history of the entire species. Conchs from 7,000 years ago had more than 66 percent meat, but as scientists from the Smithsonian Tropical Research Institute found in 2014, "because of the ongoing harvesting of large shellfish, it has become an advantage for the animal to grow up in small size More, resulting in evolutionary change. "

Scientists from Woods Hole have found similar changes in cod, salmon, and rosette: when large fish are directed, smaller versions become more successful and transfer their genetic traits, including their smaller size.

The thing is, we know for decades that selective fishing for large men and skews species.

But there was a lot of money involved. Snow crab is an important fishing and value in Nova Scotia, Prince Edward Island, New Brunswick and Newfoundland and Labrador

So of course we did it anyway.

It is daunting indeed.

Russell Wengersky 's column appears at 36 Celtweir Newspapers and websites in Atlantic Canada. He can reach at [email protected] – Twitter: @ wangersky.

Related story:

Not enough big men in Newfoundland shares the snow crab: researchers

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Time and tide are not waiting for anyone


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