Historic levels of winter coho runs are estimated to have been between 3,000 and 5,000 fish annually. Nearly 200 were once counted within the five-mile tributary known as Devil's Gulch Creek alone.
Oldtimers remember catching coho the size of a grown man's leg as the salmon swam upstream to spawn.
Now the tallies have dropped into the hundreds. Park Service biologists have spotted about 50 coho salmon in Devil's Gulch Creek so far this year, a meager count considering West Marin is home to 10 percent of this threatened species. If enough genetic data can be obtained from the local population, however, scientists may be able to determine if the coho indigenous to West Marin are a unique stock that can never be replaced anywhere else - or perhaps a seed stock that can help replenish larger creek systems like those in the Russian River watershed. The salmon's rigid, three-year life cycle makes it difficult to survive a changing environment. Coho spend a year and a half in freshwater streams, then a year and a half in the Pacific Ocean before returning to their home stream to spawn and die.