Because they don’t go through debilitating spawning cycles, sterilized trout can grow to impressive sizes. That’s the reason that most sterilized fish are released into Washington waters.
The reasons why sterilized trout are now being planted in Idaho streams, however, is to provide additional fishing while still preserving the genetic base of wild trout populations.
The Idaho Fish and Game Department has released sterilized trout in the St. Joe and Coeur d’Alene rivers, as well as in three southeastern Idaho streams.
Eastern Washington anglers long have hooked sterilized trout. The first to be released into lakes were those surgically sterilized by members of the Inland Empire Fly Fishing Club. However, the fly fishers soon became aware that the gonads of the fish regenerated and they abandoned their experiments.
Later, Dr. Gary Thorgaard, a Washington State University geneticist, in cooperation with the fly club, developed a method of sterilizing fish by heat-treating eggs. Later, fisheries agencies and operators of commercial hatcheries began experimenting with other methods of producing sterilized trout.
One of the most successful in the Northwest has been Edward J. McLeary, president of Troutlodge Inc. McLeary’s hatcheries north of Moses Lake produce sterilized rainbows for the Washington State Fish and Wildlife Department and other agencies, as well as for operators of private fishing lakes.
The Inland Empire Fly Fishing Club has purchased about 5,000 sterilized rainbows for Amber Lake, a selective fishery lake south of Spokane. Theoretically, those that survive fishermen’s hooks will become trophy trout in a few years.
The fish and wildlife department is planning to release good-sized sterilized trout into Quail Lake, scheduled for rehabilitation. Quail, about five miles north of Othello, is a fly fishing-only, catch-and-release lake. It has the potential of producing large trout.
Sterilized trout have been and are being released into Washington waters only to provide huge rainbows for anglers.
Idaho decided to conduct a two-year experiment to determine whether sterile trout released into streams live, grow and are caught as well and as often as the non-sterilized fish. Unlike normal trout, the sterilized fish won’t spawn with wild trout and thus affect the genetics of wild stream populations.
“Stocking of hatchery trout in streams has come under fire recently from some angler groups and fishery biologists,” Phil Cooper, an official of the Coeur d’Alene office of the Idaho department, says in a news release about the planting of sterilized trout in Idaho streams. “The main cause for concern has been that hatchery trout not caught by anglers can survive and reproduce with wild trout.”
He says research has shown that enough hatchery trout have survived in a number of streams in the West to significantly alter fisheries. “Idaho biologists hope the use of sterile fish will enable Fish and Game to meet the needs of anglers who like to catch hatchery trout while doing a better job of protecting the genetic base of wild trout populations,” he says.
To test the success of the sterile fish in producing fishing opportunities, Cooper says, equal numbers of both sterile and normal fish were released into the streams. Anglers who fish the St. Joe and Coeur d’Alene in areas where the trout have been released will see signs saying that experimental fish have been released in those areas. Cards will be available at the site for anglers to fill out if they catch a tagged trout.
The test fish have a small wire tag in their lower jaws. The department wants fishermen to send the tags to a state or regional office. By turning in a tag, an angler’s name will be entered into a drawing for a gift certificate worth $100 to $200.
Cooper says not all test fish were tagged. Only 600 for each stream are wearing tags.
Normal fish have two sets of chromosomes. Sterilized trout, called “triploids,” have three pairs of chromosomes; they can’t spawn.
Idaho bought triploid eggs from a commercial hatchery for the two-year study. The sterilized eggs were hatched at the Nampa hatchery and reared into 9-to 12-inch trout.
If the study indicates that sterilized trout behave like normal hatchery fish, it’s possible that Idaho Fish and Game will release only sterilized fish into several streams where there are wild trout populations that should be protected.
In Washington, some anglers’ groups have been critical of the Fish and Game Department’s practice of using hatchery steelhead to build up steelhead runs in streams where there are wild populations of steelhead. Maybe the department will consider producing sterile steelhead for the most sensitive streams.
, DataTimes MEMO: You can contact Fenton Roskelley by voice mail at 459-5577, extension 3814.
Subscribe to the sports newsletter
Get the day’s top sports headlines and breaking news delivered to your inbox by subscribing here.