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Salmon hatcheries cause significant, rapid genetic changes

"A fish hatchery is a very artificial environment that causes strong natural selection pressures," researcher Michael Blouin explained.
By Brooks Hays   |   Feb. 17, 2016 at 2:32 PM

CORVALLIS, Ore., Feb. 17 (UPI) -- New research proves that hatchery and wild fish possess significant genetic differences -- differences that can passed onto subsequent generations.

Wild fish raised in hatchery conditions produced genetically unique offspring. Compared the offspring of wild fish, the first-generation hatchery fish featured differences in their expression of 700 genes.

Differences in survival and reproductive abilities between wild fish and released hatchery fish have long suggested genetic differences, but the latest research -- conducted at Oregon State University using steelhead trout -- confirms the phenomenon.

The research was published in the journal Nature Communications.

"A fish hatchery is a very artificial environment that causes strong natural selection pressures," Michael Blouin, a professor of integrative biology at Oregon State, said in a press release. "A concrete box with 50,000 other fish all crowded together and fed pellet food is clearly a lot different than an open stream."

Blouin and his colleagues aren't exactly sure what traits are being expressed by hatchery fish, but included in the 700 genes are many linked with tissue regeneration and the immune system. Hatchery fish regularly suffer wounds and are more susceptible to disease outbreaks.

"We observed that a large number of genes were involved in pathways related to wound healing, immunity, and metabolism, and this is consistent with the idea that the earliest stages of domestication may involve adapting to highly crowded conditions," said study author Mark Christie.

Blouin, Christie and their research partners expected to see some genetic differences, but were surprised to the process of evolution playing out in just a single generation of domestication.

"We expected hatcheries to have a genetic impact," Blouin said. "However, the large amount of change we observed at the DNA level was really amazing. This was a surprising result."

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