California Sketches: Salmon’s fight for survival in an engineered world
11/24/2013 12:00 AM
08/23/2014 8:39 PM
Nothing symbolizes “made in California” more than the iconic salmon.
Chinook salmon, born in inland watersheds, migrate to the sea to mature and return to where they were born, to reproduce. But their access to natural spawning grounds in the foothills and mountains is prevented by dams on most of California’s waterways. The salmon’s fight for survival on the American River exemplifies the consequences of man engineering nature.
While Nimbus and Folsom dams provide hydroelectric power and flood control for us, they block miles and miles of habitat for salmon to lay and fertilize eggs. Man turned his attention to rescuing salmon as their populations declined. Completed in 1958, the Nimbus Fish Hatchery creates generations of salmon and steelhead. Here, migration ends and begins.
When the fall run of chinook salmon returns, the hatchery erects a barricade across the river. Hundreds of people come to celebrate the heroism of these fish, to marvel at the wonder of nature. This year, thousands of salmon have fought their way back to fulfill their biological destiny. Against cascading water, salmon enthusiastically leap 20 levels of the fish ladder, in bubbly anticipation of spawning. These chinook are native but not wild.
About 6,000 salmon entering the hatchery will produce 4.4 million eggs to be artificially fertilized. Hatchery-bred salmon differ from those born wild, where diversity strengthens genes and the species. While the abundance of salmon is a tribute to the success of hatcheries, some scientists worry about the long-term survival of the species.
In 2008, the population crashed to the edge of extinction. A bold decision to truck 19 million juveniles directly to San Francisco Bay saved this generation. Ideally, the salmon are released into the river at the hatchery near Hazel Avenue. Sometimes they are trucked farther downstream to help ensure their survival.
After their release, juveniles swim to the Pacific Ocean, as far as Siberia or Japan, for three to five years before heading home. Shiny silver chinook, 3 feet long and 30 pounds, will pass under the Golden Gate, navigate the Delta and swim up the Sacramento River and into the American. Leaving salt for fresh water, skin darkens, reddens, mottles white with fungus, and fearsome jaws jut.
Downstream from the hatchery, I’m floating in a canoe over newly laid gravel designed as natural sites by habitat managers for salmon to spawn. Not gentle creatures, they’re powerful and swift. They leap from the river and skitter over shallows splashing. Their energy fills the air. They’re driven. Post spawning, they lay gasping and dying. Spent carcasses float and bump gently against the shore, to the sounds of hundreds of crying gulls waiting to feast. Mission accomplished.
Salmon, one indicator of the health of our ecology, connect the ocean to California’s interiors. Vital nutrients pass from sea to soil, from vineyards to forests, across a diverse and challenged system. A vital source of protein, 100 species depend on salmon, from birds to humans to killer whales. And salmon contribute hundreds of millions dollars to California’s economy.
Charles Darwin said that it’s not the most intelligent or the strongest species that survives, but the most adaptable. In our engineered world, salmon are struggling to adapt, and now their very survival is dependent on man.
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