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Idaho Fish and Game

Millions of hatchery smolts get clipped before leaving for the ocean

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By Roger Phillips, Idaho Fish and Game public information specialist

It’s no secret that Idaho steelhead and salmon anglers rely on hatcheries for fish that they can take home and eat, and anglers can identify “keepers” because a small fin on their back is removed when the fish are young. The clipped adipose fin does not grow back – letting anglers identify hatchery fish for harvest. What’s less known is how the fins get clipped.

Idaho hatcheries produce about 20 million young salmon and steelhead annually that are released in the spring to migrate to the ocean. Clipping millions of tiny adipose fins is a huge undertaking that used to take thousands of hours of manual labor.

Now it’s largely automated with specialized trailers traveling to hatcheries throughout the state to safely, effectively and efficiently prepare hatchery smolts for release so they can be identified by anglers, biologists and conservation officers when the salmon and steelhead return from the ocean as adults.

Machinery housed in the trailers clips fins and also implants tiny wire tags into the fish without the need for anesthetic, removal from the water, or handling by a human. The machinery has a system that holds fish immobile so coded wire tags can be inserted. Almost simultaneously, an imaging system determines the location of the adipose fin then sends an electronic message to an automated clipping device that removes the fin.

Idaho’s salmon and steelhead marking program costs about $1 million a year, but anglers do not pay for it through their fishing license dollars or salmon and steelhead permits. The program is funded by U.S. Fish and Wildlife Service, Idaho Power Company, and the Bonneville Power Administration.

You can see the fish getting marked during a series of events in the coming months. Visitor hours will be 8 a.m. to 4 p.m. on the dates listed below. For more information or details, call Idaho Fish and Game at (208) 334-3791.

  • June 2: Clearwater Hatchery, 118 Hatchery Roe Drive, Ahsahka.
  • June 16: Rapid River Hatchery, 543 Rapid River Road, Riggins.
  • July 8: McCall Hatchery, 300 Mather Road, McCall.
  • July 12: Springfield Hatchery, 1830 W. 950 South, Springfield.
  • July 28: Magic Valley Hatchery, 2036 River Road, Filer. 
  • Aug. 11: Niagara Springs Hatchery, 2131 Niagara Springs Road, Wendell.