Spring Chinook Outlook

The first, and so far only Chinook salmon of 2007, crossed Bonneville Dam on the lower Columbia River on January 19. The outlook for others expected to follow, bound for the Snake River, is for fewer fish than returned in 2006. Last year's Chinook returns were enough to allow limited seasons in Idaho. Idaho Department of Fish and Game fishery managers expect about 15 percent fewer fish this year. But they say that some limited salmon seasons may be possible in Idaho if fishery related impacts to wild fish, listed under the Endangered Species Act, stay within allowable limits and hatchery brood stock needs can be met. As Snake River spring and summer Chinook begin migrating upriver from the ocean in May, biologists will analyze in-season counts and PIT tag returns from lower Columbia River dams to assess the accuracy of the preseason forecast and the likelihood fisheries in Idaho. This year the preseason expectation is for 27,700 to cross Lower Granite Dam in southeastern Washington-nearly 11,000 of them wild fish that must be left in the river and nearly 17,000 hatchery fish, most of them marked. Though the 2006 run got a late start, the forecast was for 33,889 fish, and 32,664 returning adult fish were counted at Lower Granite. Lower Granite is the last of the eight federal dams on the returning salmon's way up the Snake River to Idaho. Recent adult run size has ranged from a high of 185,673 in 2001 to a low of 32,664 in 2006. While some runs, such as upper Columbia Chinook, were larger than the preseason prediction, 2006 was the fifth year in a row that the total run size of spring and summer Chinook crossing Lower Granite Dam declined. Unlike upper Columbia summer Chinook, however, most of the spring and summer Chinook heading up the Snake are listed under the Endangered Species Act. Fish biologists base their predictions in part on jack counts. Jacks are mostly males that return after only one year in the ocean, and their run strength is used as a relative indicator of how many two-year adults will return the following year. Jack counts have declined almost every year since 2000, when the jack count of more than 14,000 gave biologists the signal of the big return that came in 2001. But this relationship between jacks and adults in the following year, doesn't always hold. In 2003, the jack count was twice as high as the 2002 count, but the adult return the following year was lower than the previous year. Despite variability in the relationship, biologists still view the significant decline in jack counts from 2005 to 2006 as a likely indicator that the adult return in 2007 will be smaller than in 2006. Another observation that may foretell a smaller return of adults in 2007 is that those adults originate mostly from juvenile fish that migrated to the ocean in 2005, a year of less than optimal migration conditions because of low snow pack and documented declines in ocean productivity. It's too soon to call the game; only time and the dam counts will tell.