Idaho Fisheries managers say most spring chinook bound for the Gem State have already passed Bonneville Dam on the Columbia River, meaning the run to date is not expected to improve.

There is a slight chance, however, that genetic testing at Lower Granite Dam on the Snake River could bump up the harvest share for anglers fishing on the lower Salmon and Little Salmon rivers. Of course those tests also could result in a reduction in harvest share.

Joe DuPont, regional fisheries manager for the Idaho Department of Fish and Game at Lewiston, said the latest projections indicate a harvest share of about 1,100 adult chinook on the lower Salmon and Little Salmon rivers. Anglers on the lower Salmon started hooking fish last week, and the fishing period that began Thursday and runs through Sunday could produce better fishing.

On the Clearwater River, DuPont said the latest numbers show hatcheries will fall about 420 fish shy of meeting spawning goals. As such, he said there is no hope the Clearwater River or its tributaries will reopen to chinook fishing this spring.

The run estimates are made by tallying detections of tags at Bonneville Dam. Hatchery chinook are implanted with tiny tags as juveniles, allowing fisheries managers to track their progess as they migrate to the Pacific Ocean and then return to fresh water one to three years later as adults. The adult detections give fisheries managers a good idea on the strength of the run.

But the system isn’t foolproof, and the tags often underestimate the run. DuPont said sometimes fish shed the tags or fish with the tags don’t survive as well as fish without tags. He also said the degree to which tagged fish represent the run can vary from year to year.

To back check the run projections based on tag detections, the agency uses genetic sampling. Biologists trap and test about 20 percent of the run at Lower Granite Dam. Through analysis of tissue samples, they can determine where each hatchery fish came from and produce a more accurate prediction of the return to various hatcheries.

DuPont said that work will be completed in the next week or so.

Barker may be contacted at ebarker@lmtribune.com or at (208) 848-2273. Follow him on Twitter @ezebarker.

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