The California Fish and Game Commission this week voted to protect Northern California's coho salmon under the state's Endangered Species Act after adopting a plan to restore the habitat of the increasingly scarce fish.

The commission's decision on Wednesday capped years of deliberations on how to best help replenish stocks of coho — or silver — salmon, which have been depleted by extensive fishing and water diversion as well as muddy runoff, often triggered by land development and logging operations. The runoff clogs clear-running streams needed for spawning.

The decision adds a second level of protection for a species listed as endangered by the National Marine Fisheries Service since the late 1990s.

The state commission decided in August 2002 that coho in California's coastal rivers and streams north of San Francisco were so scarce that it was time to add them to the state list of threatened and endangered species. But the commission postponed final action until this week to allow the state Department of Fish and Game to prepare a recovery strategy.

That strategy, adopted Wednesday, was developed by a group of government officials and landowners as well as timber and farming interests. It relies on incentives and volunteer projects to resuscitate salmon streams, rather than enforcement actions by the understaffed Department of Fish and Game, said Gail Newton, the department's coho recovery team leader.

For instance, instead of forbidding farmers to pump water from streams or rivers when water levels get too low, the plan allows farmers to apply for grants to install pumps that automatically shut off when rivers drop to levels that harm fish, Newton said.

The 700-page plan recommends that the state Board of Forestry enforce rules to protect imperiled watersheds. Such rules would require loggers to spare the largest trees near streams. The big trees, ecologists say, are needed to shade stream water and keep it cool enough for salmon to survive.

None of the commission's decisions will alter rules that have prohibited fishing for coho in streams or in the ocean since 1998, Newton said. "You cannot catch coho, period," Newton said.

California fishermen now catch chinook salmon, also called king salmon, which do not spawn as far upstream as the coho and thus do not face the same threats from timber harvesting and other human activities to their spawning areas.

State officials expect it to take 45 to 60 days for coho to come under state protection as a threatened or endangered species. Specifically, those coho that spawn in streams from San Francisco to Punta Gorda near the Mattole River in Humboldt County will be added to the state's endangered species list. Those north of Punta Gorda will be listed as threatened.