A new study has revealed that the impact of a hatchery environment on steelhead trout is so profound that in just one generation genetic traits are developed that cost fish the natural ability to be able to survive in the wild.
The findings, published in Proceedings of the National Academy of Sciences, have surprised researchers by the pure speed at which hatchery fish seem to evolve.
“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.”
The study was the result of a 19 year analysis of steelhead trout in Oregon’s Hood River.
Billions of hatchery reared fish are released into the wild each year. The steelhead in this study are on the endangered species list and part of the recovery plan includes supplementation with hatchery fish - so a better survival rate is important.
The challenge for the researchers now is to see if this story is similar in other fish species, identify the genetic traits that evolve and work to slow that rate of domestication.
