It’s been a slow start for the return of coho salmon in Marin’s creeks this winter, raising concerns among biologists that it could be a second consecutive poor year for the endangered species. “We are hoping there will be a second wave of salmon that will ride in on the next big storm,” said Christopher Pincetich, watershed biologist for the Forest Knolls-based Salmon Protection and Watershed Network. “That’s what everyone is hoping for.”
But so far the run of spawning salmon in Lagunitas and San Geronimo creeks is only about 25 percent of what would be expected this time of year, Pincetich said. The numbers were also low last year for the West Marin creeks.
And in Redwood Creek, which runs through Muir Woods National Monument in southwest Marin, the news isn’t any better. Last year only one pair of spawning salmon were known to appear in the creek.
“We have only seen one juvenile coho on the Muir Woods grounds,” said Tim Jordan, educational coordinator at the national monument. “We are holding our breath, hoping for more rains.”
The lifecycle of the coho is rigid: In the winter as creeks swell with rains, fish return to the streams in which they were born to spawn and then die. Young fish hatch from eggs in the gravel in the spring and then spend another year in the streams feeding and growing while seeking refuge in deep, cold pools.
After enduring a summer and winter they then head out to sea in their second spring to feed along the coast. Fish return to their streams from the ocean to spawn, die and continue the cycle of life.
The fish need good flows of water in creeks to navigate upstream, but a dry spring meant early rains simply soaked into the ground. And a dearth of heavy rains this winter has kept fish idling off the coast, waiting for storms to raise creek levels so they can make it in.
Even if the heavy rains arrive, it’s possible that this year’s number may remain low due to the flooding that occurred in the winter of 2005-06, when raging waters may have flushed out many of the young coho that were in creeks.
Marin’s salmon run is one of the more critical in the state. The Lagunitas watershed has one of the largest remaining populations of wild coho salmon in central California. Coho have gone extinct in 90 percent of California streams that once supported the species, usually because of development along creeks which fills them with sediment.
“It’s a case where conditions are not improving as fast as they are deteriorating,” Pincetich said.