by Eric Ettlinger
Salmon have returned to Lagunitas Creek! The annual migration of adult salmon from the ocean into Lagunitas Creek and its many tributaries got an early start this year, following unusually early and heavy rainfall in October. MMWD biologists observed four coho salmon near the entrance to the Samuel P. Taylor campground on October 22, before systematic spawner surveys had even begun. We conducted our first spawner survey of the 2009-10 season on November 4, and weekly surveys will continue through February.
Surveys last week, which covered nearly eight miles of Lagunitas Creek, found five new salmon redds (gravel nests), mostly downstream of Samuel P. Taylor State Park. The size and shape of these redds indicated that they were likely built by Chinook salmon. A partial skin of a Chinook salmon was also found in the same stream reach.
We don’t expect any further spawning activity until we get more rain, which is forecast to return next week. Looking ahead to the rest of the spawning season, we’re expecting lots of rain and (keep your fingers crossed) lots of fish. A moderate-strength El Niño is expected to result in a wet winter for California, after three drier-than-average years. More rain doesn’t produce more salmon, but it does allow the returning spawners to migrate further upstream to the best spawning grounds. In addition, researchers at the University of Washington are predicting record ocean survival rates for coho salmon this year, based on a combination of strong coastal upwelling, cold water and abundant copepods (invertebrates that salmon love to eat). The adult coho expected to return this year are the surviving members of a large cohort of juveniles observed in 2007. If the predicted ocean survival rates are correct, we may see anywhere from 500 to 1,300 coho salmon spawn in the Lagunitas Creek watershed this year. After seeing less than 50 coho spawners last year, we’re eagerly anticipating a busy spawning season.