By Keith Ridler, Associated Press

BOISE, Idaho (AP) — A relatively new $13.5 million hatchery intended to save Snake River sockeye salmon from extinction is instead seeing thousands of hatchery-bred fish die before they ever get to the ocean, and fisheries biologists in Idaho think they know why.

The Department of Fish and Game in information released this week says water chemistry at the Springfield Hatchery in eastern Idaho is so different from that in the central region that the young fish can't adjust when released into the wild.

"It's not a disaster, it's part of what you experience when you open a new hatchery," Paul Kline, Fish and Game's assistant fisheries chief, said in a post on the agency's website.

Idaho Rivers United, an environmental group, blasted the report as more reason for removing four dams on the lower Snake River that impede salmon.

"Until we address main-stem survival we're missing the biggest opportunity for these amazing fish," Kevin Lewis, the group's executive director, said in a statement.

Sockeye salmon are a prized sport fish and the Idaho run is culturally important to the Shoshone-Bannock Tribes. An estimated 150,000 sockeye returned annually to central Idaho, and Redfish Lake was named for the abundant red-colored salmon that spawned there.

Federal officials say the run began to decline in the early 1900s due to overfishing, irrigation diversions, dams and poisoning, teetering on the brink of extinction in the early 1990s.

The fish have been the focus of an intense recovery program centered at Fish and Game's Eagle Fish Hatchery in southwestern Idaho after being listed as endangered under the Endangered Species Act in 1991.

The Springfield hatchery was completed in 2013. Salmon eggs from the Eagle hatchery and the federally operated Burley Creek Hatchery in Washington state are transported to Springfield where they are raised until they are ready for release as young fish, called smolts, into the Salmon River.

The goal has been to release 1 million smolts with the hope that up to 5,000 of them could survive the ocean odyssey to return annually as adults to Redfish Lake. This year, 162 adults returned, none from the Springfield Hatchery.

Fish and Game officials say smolts from the hatchery released in central Idaho are not surviving.

The main theory, officials say, is that water at the Springfield Hatchery has a high amount of dissolved minerals, called hard water, while the water at Redfish Lake and the Salmon River does not, making it soft water.

Young fish headed for the ocean transition from living in fresh water to salt water. Biologists say the additional stress of trying to also adjust from hard water to soft water could be killing the salmon.

Idaho officials say they plan on trying various solutions, including releasing fish directly into Redfish Lake in the fall as pre-smolts, raising more sockeye at the Sawtooth Hatchery in central Idaho, and gradually softening water as fish are transported from the Springfield Hatchery in trucks to central Idaho.

The Bonneville Power Administration paid for the Springfield Hatchery as part of federally required mitigation to replace fish killed by hydroelectric projects that provide power to the region.

"We are confident that this hatchery is still viable and that our partners will find a solution," said David Wilson, spokesman for the agency.

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