The impact of hatcheries on salmonids is so profound that in just one generation traits are selected that allow fish to survive and prosper in the hatchery environment, at the cost of their ability to thrive and reproduce in a wild environment.
Researchers confirmed that a primary impact of hatcheries is a change in fish genetics, as opposed to a temporary environmental effect.
"We've known for some time that hatchery-born fish are less successful at survival and reproduction in the wild," said Michael Blouin, a professor of zoology at Oregon State University. "However, until now, it wasn't clear why. What this study shows is that intense evolutionary pressures in the hatchery rapidly select for fish that excel there, at the expense of their reproductive success in the wild."
When thousands of smolts are born in the artificial environment of a hatchery, those that survive best are the ones that can deal, for whatever reason, with hatchery conditions. But the same traits that help them in the hatchery backfire when they return to a wild river, where their ability to produce surviving offspring is much reduced.
"We expected to see some of these changes after multiple generations," said Mark Christie, an OSU post-doctoral research associate and lead author on the study. "To see these changes happen in a single generation was amazing. Evolutionary change doesn't always take thousands of years."
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Bron: artikel van Oregon State University
