Chinook Migrations Running Both Ways

Young chinook produced by the big adult return to Idaho in 2001 have started their journey to the ocean. Biologists estimate that as many as 51,900 female spring and summer chinook may have spawned in Snake Basin tributaries in 2001 compared to the 1990-2000 average of 4,750 females. Most of them spawned in the Salmon and Clearwater drainages. As a result, the spring and summer chinook smolt (juvenile salmon ready to move to the sea) migration this spring may be the highest recorded in the last 11 years. The estimate of natural chinook smolts that will arrive at Lower Granite Dam is 1.7 million, compared to an average of 827,000 chinook smolts for the previous 11 years (1992-2002). Full hatcheries mean that lots of hatchery smolts will also be heading downstream. There are indications that the chinook smolt migration started early and will be as big as predicted. The department runs a smolt trap near Whitebird on the lower Salmon River to monitor the migration. Counts of natural chinook smolts rose dramatically on March 17. Hatchery chinook, such as those from Rapid River Hatchery in the Little Salmon drainage, were right behind them. Early movement is seen on the other end of the system too, as adult spring chinook have already started crossing Bonneville Dam in substantial numbers, earlier than usual. Through March 25, about 8,560 adults had crossed the dam, compared to a five-year average of 1,100 adults crossing the dam by the same date. In the bigger run years of 2000 through 2002, numbers of spring chinook dramatically increased at Bonneville Dam at the beginning of April, so this year looks to be a couple of weeks early. Tags indicate that most of the adults seen so far are three-ocean fish, salmon that have lived three years in the Pacific. The Idaho fish are primarily bound for Dworshak and Rapid River fish hatcheries. Chinook salmon return to Idaho from the ocean over three years.One-ocean fish are mostly small males called jacks while adult salmon return after two or three years in the ocean. Typically, the three-ocean adults are the first to return to the Columbia River on their upstream journey and this year is providing dramatic evidence to support that fact.