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Hatchery Fish Can't End Peril to Wild Chinook

by Staff
The Idaho Statesman, May 14, 2001

Extinction remains strong possibility for native stock

(Kim Hughes) Anglers and boaters ply the Clearwater River in the Orofino area, such as this stretch below Dworshak Dam. This year's hatchery chinook salmon run is expected to draw many more people to the area. Anglers and boaters ply the Clearwater River in the Orofino area, such as this stretch below Dworshak Dam. This year's hatchery chinook salmon run is expected to draw many more people to the area.

Salmon derby slated The Orofino Chamber of Commerce is sponsoring the first "Hook the Chinook" governor's salmon derby June 23 through July 1. There is a $10 entry fee, and 90 percent of the money will be paid back as prizes. The winner will also receive a plaque from Gov. Dirk Kempthorne. All anglers must purchase a ticket before fishing in the derby. The heaviest fish wins. All fish entered must have gills intact and entrails removed. For more information, call (208) 476-4335.

Wild chinook salmon have been on a well-publicized downward spiral and are facing possible extinction in the long term.

All of Idaho's wild spring, summer and fall chinook are listed as threatened under the federal Endangered Species Act, except for Clearwater salmon.

The Clearwater's chinook were essentially wiped out by the Lewiston Dam when it was built in 1927.

The dam was removed in 1973, and hatchery chinook were used to restore the Clearwater's salmon runs, so they are not considered wild salmon.

Hatchery chinook are managed differently than their wild cousins.

When the Columbia River and Snake River dams were built between 1938 and 1975, numerous fish hatcheries were created in Idaho to offset wild salmon runs lost when dams blocked them from their natural spawning grounds.

Hatchery salmon runs have two purposes: to perpetuate themselves and provide fish for anglers to catch.

This year, a series of coincidences produced a much-larger-than-normal run of hatchery salmon.

About 102,000 spring chinook had returned over Lower Granite Dam by Monday. That compares with the 10-year-average run of 9,300 spring chinook, according to salmon counts at Lower Granite.

A strong run of adult chinook returned to Idaho in 1997, which filled hatcheries with eggs.

Those eggs eventually became 7.3 million juvenile salmon, also known as smolts, which were released into Idaho rivers in the spring of 1999. Those smolts rode a big spring runoff to the ocean, where they found good feeding conditions.

Most of the class of 1999 smolts are now migrating up the Clearwater and other Idaho rivers as "two-ocean" adults, which means they have spent two years in the ocean.

There probably will be an echo effect next year because every year's class of smolts that migrates to the ocean returns over a three-year period.

About 10 percent of the year class returns after one year in the ocean. Those fish are known as "jacks" because they are almost always young male salmon.

About 65 percent to 70 percent return as two-ocean adults, and the remaining 20 percent to 25 percent return as "three-ocean" fish, which are massive chinook weighing upward of 30 pounds.

Three-ocean fish from the class of 1999 will return next year and augment the smaller class of 2000. The year 2000 smolt class was 5.5 million fish, about 2 million fewer than 1999.

However, the future does not look bright for hatchery salmon. The 2001 smolt class released this spring was 2.9 million fish, less than half the size of the class of 1999.

The 2001 smolts are also facing harmful drought conditions.

Salmon need big spring runoff to flush them to the ocean. Low water means slower, warmer rivers, which can be lethal to smolts when their bodies are adapting to saltwater. Low, slow rivers also make the smolts more vulnerable to predators.

With excellent migration and ocean conditions, about 2 percent of a year's class of smolts will return as adults. When conditions are poor, as few as 0.2 percent of smolts return as adults.

Hatchery Fish Can't End Peril to Wild Chinook
The Idaho Statesman, May 14, 2001

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