YENTNA RIVER -- The Alaska Department of Fish and Game is going back to the future after the discovery that far more sockeye salmon are returning to the Yentna River than were accounted for by modern technology.

Visual counts of sockeye returning to Yentna tributary spawning streams have for several years now found far more fish than were counted by a state sonar placed along the lower river. Fish and Game first responded by trying a new sonar. Counting accuracy wasn't much better.

So this week the agency announced that after "an exhaustive analysis of historical data," it is abandoning sonar in favor of counts from weirs near the mouths of Chelatna, Judd and Larson lakes. Sonar, it says, will continue to run to provide an index for how the run is progressing while commercial fisheries are under way in Cook Inlet.

But spawning counts will be based on fish through the weirs. The spawning goal for the Yentna River system is 90,000 to 160,000 sockeyes. Sonar counts have for years made it appear returns were inadequate or barely within the lower end of that range. Now it appears the river might regularly have been meeting or exceeding spawning goals.