GRANTS PASS - Salmon produced by hatcheries in the Columbia Basin are no substitute for salmon spawned naturally in rivers, but can still help restore wild runs if significant changes are made, a team of scientists reported Friday to Congress.

The report said fish spawned in the wild have the genetic diversity to weather changes in their environment, but 130 years of substituting hatcheries for habitat has produced fish that are slowing efforts to restore dwindling runs.

"If hatcheries continue to be operated the way they are, the plight of natural populations may become worse rather than better," said Lars Mobrand, a Seattle consultant and former chairman of the review group.

The same narrowing of genetic variation was blamed partly for the crash last year of fall chinook on the Sacramento River in California, which led to a shutdown of sport and commercial ocean fishing off California and most of Oregon.

"We have so narrowed the genetic makeup of these populations that when we see things like changing ocean conditions and perhaps even climate change we don't have the ability for salmon to adapt to those things," said Peter Paquet, a member of the Hatchery Scientific Review Group. "Historically, salmon have been good at this - they have been for 10,000 years of various climate conditions."

The report, prepared at the behest of Congress, said outdated hatchery practices should be changed so that they focus on broadening genetic diversity and reducing the harm to wild runs, rather than pumping out the most young fish possible.

Studies have shown that hatchery fish produce up to 50 percent fewer eggs than wild fish when they spawn in the wild, and that behavioral characteristics that help fish thrive in hatcheries can make them less successful in the wild.

The Hatchery Scientific Review Group spent two years reviewing 358 populations of salmon and steelhead in the Columbia Basin and hatcheries producing 178 strains of fish.

They found most hatcheries are still operating to outdated standards, and some are so poorly maintained they violate environmental laws with their discharges.

Recommendations focused on ways to maintain and expand genetic diversity among fish, such as using wild fish from local waters to spawn young fish, and taking steps to prevent hatchery fish and wild fish from mixing on spawning grounds.

The panel said reforming hatchery practices would increase salmon runs more quickly than habitat restoration, and combined with habitat restoration would trigger stronger improvements than either one by itself.

Basin hatcheries date to 1877. Dozens are now operated by states, tribes, utilities and the federal government - intended to make up for spawning and rearing habitat destroyed by dams, logging, agriculture, and urban development as the Northwest's population has grown.

More than 80 percent of fish returning to the mouth of the Columbia are spawned in hatcheries, and 13 wild runs are protected by the Endangered Species Act.