Idaho Uses Sterile Fish To Keep The Gene Stream Pristine

Sterile trout made a splash in Idaho this summer. But the program had nothing to do with raising trophies.

“We’re putting them in streams to provide sport fishing while trying to eliminate the possibility of hatchery fish breeding with wild species,” said Dan Shill, Idaho Fish and Game Department fisheries biologist in Boise.

British Columbia is experimenting with the same theory. All the brook trout being stocked in the province are sterile to prevent interbreeding with threatened bull trout.

Idaho is trying to provide keeper fish for anglers while protecting the genetic integrity of native cutthroats, bull trout and steelhead.

This summer, Idaho stocked 18 streams with equal numbers of sterile and normal hatchery rainbows. Included in the study were the Coeur d’Alene and St. Joe Rivers.

Data from surveys is being analyzed this winter. So far, the sterile and hatchery fish appear to have been taken in equal numbers by anglers, said David Teuscher, Fish and Game Department study coordinator.

“These fish aren’t expected to grow to trophy proportions, since surveys show most of the hatchery fish put in streams are caught in the first three weeks.

“Research tells us that most hatchery fish put into streams die before the first winter if they aren’t caught,” Shill said.

“But some do survive, and that’s why we have hatchery rainbows spawning with native cutthroats to make hybrids. We don’t want to do that to cutthroats anymore.”

Idaho biologists don’t care whether the sterile rainbows grow to large proportions. They just want to be sure they match normal hatchery fish in return rates to the angler.

Several other states are taking a similar approach.

“Stocking sterile fish is a positive environmental issue,” said Jim Seeb, Alaska Fish and Game Department biologist. “It’s complicated, but the more we test it the more good uses will be found for maintaining sportfishing and aquaculture while protecting wild species.”

, DataTimes