With studies showing that hatchery-produced salmon are devouring legally protected wild salmon, conservationists have filed suit to halt this spring's release of more than 5 million hatchery fish in the Puget Sound region.

The move could severely curtail salmon sport fishing in years to come.

Pointing out that plans to reduce the loss of chinook salmon protected under the Endangered Species Act are more than two years overdue, Washington Trout and the Native Fish Society have filed suit in federal court in Seattle against the state Department of Fish and Wildlife.

According to the suit, the wild chinook salmon protected by the law are being eaten by coho and steelhead when both are juveniles, or smolts, waiting in freshwater rivers for their time to head to the ocean.

State officials would not comment on the lawsuit, but have said in the past they are committed to changing hatchery procedures so the fish produced there are not harming the legally protected wild fish, which spawn naturally.

The Portland-based Native Fish Society has amassed dozens of scientific studies showing how hatchery-produced fish harm wild fish stocks. And Fish and Wildlife officials have acknowledged that "predation on wild fish by hatchery fish may also negatively affect wild fish populations."

The disappearance of wild salmon concerns scientists because fish in each river are genetically distinct. This is how the fish have managed to survive in environments as starkly different as the steep, cold streams of the Olympic Peninsula rain forest and the flat Snake River running through Eastern Washington desert.