Idaho’s first anadromous fish hatchery (for oceangoing fish) opened near Oxbow Dam in January 1962, supporting the opportunity to fish for steelhead and salmon today.
Rapid River Hatchery opened in 1964, Niagara Springs in 1966 and Pahsimeroi in 1967. They were built to mitigate for Idaho Power Company’s complex of three dams in Hells Canyon of the Snake River. In September 2013, the Springfield Fish Hatchery was completed near American Falls Reservoir.
Idaho's steelhead and salmon hatcheries were built to mitigate for the loss of these fish when hydropower dams were built on the Snake River, as well as Dworshak Dam on the Clearwater, making the 500- to 900-mile journey to and from the ocean more difficult. Today only about 25 percent of the fish that return to the Snake River system are of wild origin.
Idaho's A-run steelhead are usually found in the Snake and Salmon rivers. They return from the ocean early in the year — usually June through August — and they most often return after spending one year in the ocean. Because of their early return and short stay in the ocean they usually weigh four to six pounds and are generally 23 to 26 inches in length.
The B-run steelhead most often return to the Clearwater River, but some return to tributaries in the Salmon River. These fish usually spend two years in the ocean and start their migration to Idaho later in the summer or fall of the year — usually late August or September. Because of the extra year and the extra summer of growing in the ocean, they return as much bigger fish. Average B-run steelhead weigh between 10 and 13 pounds and are 31 to 34 inches long.
Steelhead grow even larger when they spend a third year in the ocean before they return to Idaho to spawn. These steelhead are usually larger than 37 inches and often weigh more than 20 pounds. The Idaho state record steelhead was 30 pounds and 2 ounces and was caught in the Clearwater River in 1973.
Steelhead are similar to rainbow trout except that they migrate to the ocean and return to fresh water to spawn. Anglers can fish for steelhead somewhere in Idaho from July 1 to May 31. There are no harvest seasons for wild steelhead.
The clipped adipose fin anglers are required to check for signifies a steelhead came from one of Idaho’s anadromous fish hatcheries.
More than 50 percent of all Columbia River basin steelhead come from Idaho, either spawning in the wild or raised in hatcheries.
In Idaho, 14 salmon and steelhead hatcheries, built as mitigation for losses from hydropower projects in the Snake River drainage, produce about 11 million chinook salmon, 7.5 million steelhead and 200,000 sockeye salmon for release annually.
For information see IDFG’s steelhead information page, fishandgame.idaho.gov/public/fish/?getPage=38, or the fishing planner at fishandgame.idaho.gov/ifwis/fishingPlanner/.