Unclipped Steelhead

Late in the fall it is possible to see a high proportion of unclipped steelhead in the catch. That's mostly a function of the harvest of fish with clipped adipose fins and not the marking at the hatchery before the fish were released. Most of the hatchery steelhead returning to the Clearwater this year were released as smolts to go to the ocean in 2012. In that release group there were 2,410,000 adipose-clipped and 533,000 unclipped hatchery steelhead (or 82% were clipped). We expect that the unclipped and clipped fish survive to return as adults at the same rates so the adults should be in the same proportion. Sport anglers in the lower Columbia and Snake rivers can harvest only adipose-clipped fish so that will reduce the number of those fish and change the proportion. Out of the fish numbers I mentioned above, we would expect (on average) about 21,000 clipped and 5,000 unclipped adult steelhead to return to Lower Granite Dam. Idaho's fall season sport fishery can harvest 11,000 to 12,000 of the adipose-clipped fish in the fall and none of the unclipped fish. We must also consider the natural-origin fish - they have an adipose fin too - in addition to the unclipped hatchery fish. Because of the effect of the fishery removing a large number of clipped fish and there are wild fish present, it's very likely the proportion of clipped fish in the Clearwater in December is less than 50%. That means that more than 1 out of every two fish an angler catches will be unclipped, even though when released as smolts, 82% of the hatchery fish released had their adipose fin clipped. Because anglers are harvesting only clipped fish, they significantly change the proportion of clipped fish in the river over the course of the fishing season.