The court's move means that the California Fish and Game Commission's March 2005 decision to grant the coho protection under the California Endangered Species Act will stand.

California Trout, an intervener in the case, applauded the high court's decision.

"At long last, we can celebrate victory in this case," spokesman Brian Stranko said in a statement. "We can now move on to the important work of protecting and rehabilitating coho salmon in California."

Conservation groups contend that coho habitats have been compromised by poor land-use practices that have resulted in increased river siltation, low water flows and rising water temperatures.

They say coho salmon population has been reduced by over 90 percent in California.