Critics of hatchery-raised fish claim the hatchery-rearing process affects fish genetics negatively, but Pahsimeroi Fish Hatchery Manager Doug Engemann said it’s more complicated.

At an Oct. 22 panel discussion, Trout Unlimited scientist Helen Neville said raising fish in hatcheries isn’t a viable option to replace decreasing numbers of salmon in the Salmon River. She said the domestication process affects the DNA of fish because being raised in a tank adds natural selection pressures not seen in a natural environment.

Engemann, who has been with the Idaho Department of Fish and Game for 32 years, said these pressures can affect fish, but they affect some fish more than others.

“You have to look at this in a contextual framework,” Engemann said. “The goal of good genes depends on the fish.”

Engemann said hatchery genetic management plans define the ways hatchery employees can breed fish. The plans outline what can and can’t be done with hatchery fish so their genetic health remains satisfactory.

According to Engemann, typically a hatchery breeds fish on a one-to-one basis, which means one male and one female are used to fertilize a batch of eggs. However, if the return of salmon is low, the management plans might allow hatchery workers to fertilize two females with one male.

“A lot of it’s a numbers game,” said Engemann.

The hatchery manager said the steelhead raised at the hatchery don’t get mixed into the natural population. The hatchery practices reproductive isolation that segregates hatchery steelhead from natural ones. This prevents negative traits in hatchery fish from being passed on to naturally born fish.

“If they’re hatchery steelhead, they don’t touch the natural population,” said Engemann.

Engemann said the goal of hatcheries isn’t to completely replace natural populations of fish, but to supplement them. He said he and his staff are trying to provide for anglers who fish the Pahsimeroi River an opportunity to enjoy the outdoors, not lecture them on the ethics.

“We are trying to build up an abundance of fish and do it responsibly,” said Engemann.

Another complaint against hatchery-raised fish is because of the tight confinements of fish tanks there is an increased chance of injury, which can rapidly lead to disease.

Engemann said hatchery employees take every precaution to prevent the spread of disease and bad genes. He said it starts with an iodine bath employees give eggs once they’re fertilized.The eggs sit in the bath for 60 minutes to make sure no illnesses like whirling disease, which is a neurological disorder that causes fish to swim in a circle till they die, get passed on to natural populations.

Engemann said such policies are a staple at all hatcheries in Idaho to prevent the further decline of salmon in the state’s rivers and streams.

“I think the message gets missed that we’re concerned about this issue, too,” said Engemann.