Conflicting data confuses sockeye salmon forecast

Posted: Friday, December 22, 2000

KENAI (AP) -- Two conflicting sets of data have muddied the Cook Inlet sockeye salmon forecast for next year.

Numbers released by the Alaska Department of Fish and Game contain a 1.5 million fish ''fudge factor'' because two different models were used for the estimate, according to Mark Willette, a department research project leader for upper Cook Inlet.

In numbers released Wednesday, Fish and Game officials in Soldotna forecast a total Kenai River sockeye run of 2.4 million.

For all of upper Cook Inlet, the total run is predicted at 4.2 million sockeye, with an escapement goal of 1.5 million and a harvest estimate of 2.7 million.

Kenai Peninsula Fishermen's Association vice president Paul Shadura, a setnetter on Kalifornsky Beach, said the overall run looks positive.

''That would be much better than last year. It's a healthy run, and that's what we're looking for,'' he said. ''Anything better than the 1.2 million catch last year is a positive note for the industry.''

Willette said fishermen have a reason for optimism. Still, there's that fudge factor surrounding the return figure.

Willette said he used the mean of two different models to estimate next year's sockeye run.

''We felt the best approach was to take the mean of the two, that way we were using all the information we had,'' Willette told the Peninsula Clarion. ''But there is no way of knowing if we're correct.''

One model comes from calculations based on how many sockeye fry were counted three years ago in Kenai Lake, while the other compares the return of ''sibling'' fish last year. Siblings to this year's 5-year-old sockeye were last year's returning 4-year-olds.

For the 2000 season, the department used the fry model, which predicted a return of 4.5 million sockeye to upper Cook Inlet, while the actual return was 2.9 million. The Kenai River sockeye return was 1.4 million, a million less than predicted.

The fry model predicts a return of 2.5 million 5-year-olds, based on a count in 1997. The sibling model predicts a return of 980,000 5-year-olds and is based on the weak return of last year's 4-year-olds.

''We have two models that predict very different returns, and we have no way of knowing which is more accurate,'' Willette said.

Because of the uncertainty, he said the department split the difference, and issued a prediction of 1.74 million Kenai River 5-year-olds, which typically account for 60 percent or better of the river's total return.

If the sibling model prevails for 2001, the total run would be 760,000 sockeye less. If the fry model proves more accurate, the run would be 760,000 more than the mean prediction.

In the case of the larger estimate, next year's sockeye run would be the fourth largest in upper Cook Inlet in the past 10 years.

With a total run of 2.4 million all-age sockeyes predicted for the Kenai River, the in-river escapement goal is between 750,000 and 950,000.

The 2001 Kasilof River return is expected to be 688,000, with an in-river escapement goal of between 150,000 and 250,000.

That return is down from 2000, which Shadura described as disappointing.

The 2000 sockeye return in the Kasilof was 577,000 fish, compared with a preseason forecast of 786,000.

Returns to the Crescent River in 2001 are predicted to be 63,000, while the Fish Creek return is expected to be 20,000. The Susitna River run is estimated to be 425,000, while the return to what are called ''minor'' systems is predicted at 545,000.



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