Researchers at the Marin Municipal Water District said that significant rainfall totals late last year mitigated drought conditions and may have aided in bolstering the coho salmon population at Lagunitas Creek, a 24-mile stream in Marin County where the fish spawn every winter.
Eric Ettlinger, an ecologist for the agency, told the Marin Independent Journal that the creek saw one of the largest salmon runs in a decade and that fish surveyors discovered 330 coho egg nests — the second-highest count recorded in that span of time. Three hundred and seventy nests were counted during the winter months of late 2018 and early 2019.
“For the public, it was an amazing year because [salmon] were all over the watershed,” Ettlinger told the outlet. “People were seeing them in popular spots like Devil’s Gulch and Leo T. Cronin Fish Viewing Area and spawning over an extended period of time. They said they had not seen so many salmon in years and that this year was the best viewing they had ever seen.”
The news comes after Salmon Protection and Watershed Network (SPAWN) biologist Ayano Hayes spotted the shiny red tail of a coho salmon in the nearby waters of Montezuma Creek in Forest Knolls earlier this year. Hayes told SFGATE it was the first sighting recorded of the species since 2004.
Though Hayes considers the species’ comeback in Lagunitas Creek encouraging, he said the “sudden dryness” that followed heavy rain in the months of January and February left him concerned for the survival of emerging fry, or small salmon that are just beginning to leave their gravel nest.
Coho salmon have experienced “a serious decline” since the mid-20th century, according to the California Department of Fish and Wildlife, and sand bars blocking the fish because of drought conditions heavily weighed into their demise.
However, subsequent light rain that fell in March and April provided a respite for the species, replenishing parts of the waterway and allowing younger salmon to move to safer sections of the creek downstream amid ongoing risks such as warming temperatures.
“As of now, we are still seeing schools of juveniles feeding in pools and darting around everywhere in the creeks throughout the watershed, more so than I have seen in years,” Hayes said in an email.
A stock image of a coho salmon jumping over a dam in Isaaquah, Washington.
Kevin Schafer/Getty ImagesWhile thousands of coho salmon once made their way to the Bay Area, only a few hundred now return each year, according to SPAWN. Hayes said biologists are carefully observing the creek’s water quality and temperature — conditions the salmon are “extremely sensitive” to.
But for now, “it’s reassuring to see these numbers of juveniles because it gives a greater fighting chance of survival for this cohort,” Hayes said, adding that the rain also helped 22,000 salmon at the smolt stage to migrate out to the ocean. It was the second-largest outmigration population count since SPAWN began monitoring it in 2006.
“We’ve been very fortunate this year with receiving rain at just the right time,” Hayes said. “We won’t see these fish return until they’re adults ready to spawn winter of 2023-24, but we hope ocean conditions are favorable and that this cohort continues to run strong with every return.”
