Friday, May 28, 2010

Spring Chinook Run Falling Short of Expectation

This years run of Spring Chinook on the Columbia River was forecasted to break records. Excellent ocean conditions in the Spring of 2008 and high numbers of Jacks (males that have spent one year at sea) in last years return had generated optimism that the run would be of unprecedented size. Unfortunately the run appears to be falling well short of expectations and two weeks ago biologists downsized their prediction by revising runsize estimates to a more modest 350,000 thousand fish. Now even that estimate appears optimistic and to date the run is only about 50% above the 10 year average. Traditionally, managers have largely relied on Jack counts to predict within cohort survival and subsequent returns of older fish. In recent years however, higher than normal numbers of jacks have contributed to unreliable preseason forecasts.

More information in the NW Fishletter

An old post on forecasting in the Columbia

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