SAN RAFAEL — California’s massive drought has spelled bad news for many of the state’s fish. But in a strange twist, it appears to have been a boon to coho salmon migrating from a Northern California creek.
Nearly 20,000 juvenile coho swam out of the Lagunitas Creek in Marin County into the ocean this spring, the largest salmon migration since scientists started tracking fish outflow from the creek in 2006.
The migration bump is due to the lack of rain this year, scientists say. Juvenile coho, also known as silver salmon, normally gather in the lower reaches of the Lagunitas before heading to sea.
But the abundance of coho there means some get bumped out.
This year, the fish were trapped in small tributaries because of the drought. Since they didn’t make it to the lower Lagunitas, they weren’t driven away.
“This was an unexpected silver lining to the dry conditions this year, and it is related to the unique habitat limitations in this watershed,” said Eric Ettlinger, the aquatic ecologist for the Marin Municipal Water District, which helps with the annual salmon count.
But it’s not all good news for the fish. Biologists say that only 206 salmon egg clusters, known as “redds,” were counted in the Lagunitas this year, well below the 20-year average of 250 “redds.” And the fish that headed off to the ocean may not fare as well. They are smaller than normal and could face more difficult ocean conditions due to the warming pattern known as El Nino, scientists say.
“It’s kind of a fluke of nature that allowed those fish to survive in the first place, and now these fish are leaving during an El Nino event,” said Todd Steiner, executive director of the Salmon Protection and Watershed Network, which assists with the annual salmon count. “El Nino usually means less deep-ocean upwellings and therefore less food in the ocean, so we may still end up with less fish returning.”
Information from: San Francisco Chronicle, http://www.sfgate.com