On California's Coast, Farewell to the King Salmon- page 3 | Science | Smithsonian
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Scrapped fishing boats in Fort Bragg (salvagers Bruce Abernathy and his son David) testify to the sharp decline of chinook salmon. (Ryan Anson)

On California's Coast, Farewell to the King Salmon

For the first time there's no fishing for chinook salmon on the California coast. The search is on for why the prize catch is so scarce.

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(Continued from page 2)

By now, Sacramento chinooks have lost an estimated 70 percent of their original spawning habitat in central California. Dams did the most damage, drying up riverbeds and cutting off access to mountain spawning streams. Shasta Dam, completed in 1945, is the nation's second largest, far too big for the fish ladders that in some places help salmon reach their spawning grounds. Some populations barely survived. There are plenty of complaints against hatcheries—the main one is that artificially producing millions of fish masks deep ecological problems—but without the hatcheries, the Sacramento run could hardly have rebounded from industrialization the way it did. The fall run, probably numbering about a million at its peak, was until very recently holding steady at a quarter or more of that level, enough to keep the West Coast salmon industry afloat.

Then came this summer's calamity. The official list of possible causes is more than 40 items long, ranging from bridge construction in migration areas to a surging population of Humboldt squid, grabby predators that may or may not have a taste for chinook. Scientists are looking back to 2005, when the fish that should be returning to the river now would have been sea-bound juveniles, small and vulnerable. There were poor ocean conditions off the West Coast that spring. A shift in weather patterns—possibly related to global warming—delayed the seasonal upwelling of cold, nutrient-rich water that supports the base of the marine food chain. As a result, "everything that was expecting something to eat in May died," including juvenile salmon, said Bill Peterson, a fisheries oceanographer with the National Oceanic and Atmospheric Administration.

Other experts cite freshwater dangers, since fish weakened by a stressful trip downstream are less likely to survive in a hostile ocean. This is a politically loaded argument: many of those stresses, from pollution to introduced species, are man-made. "Protecting this icon means protecting the watershed, from where these things spawn in the mountains down to the ocean," said Jon Rosenfield, an aquatic conservation ecologist based in Berkeley, California. "If you operate the rivers in the way that's best for agriculture, that's not necessarily how the water would be operating on its own."

In addition to being the most populous state, California is the most productive agriculturally. But much of its farmland, and more than 75 percent of its population, lie south of Sacramento, while three-quarters of the precipitation falls north of it. Huge dams, the Shasta chief among them, hoard water that's released downstream on demand and pumped to the Central Valley and Los Angeles. The arrangement works out for millions of people but not always for the fish, which can get disoriented in artificial flows created by water diversions and never make it to the sea.

Such problems are expensive to fix and the solutions can mean water shortages, especially for farmers, which heighten the conflict between interest groups. "The environmental community exploits the problems in nature and ignores human problems," said Jason Peltier, deputy manager of the sprawling Westlands Water District, which supplies hundreds of farms in the Central Valley. "That's their agenda. I can't understand how they get away with it. I can't understand how [the groups] push a fish-and-nature-first agenda at the expense of human socioeconomic conditions."

Over the past decade or so changes have been made to California's intricate plumbing to give salmon safer passage. Shasta Dam was retrofitted, at a cost of roughly $80 million, with a device that draws from the very bottom of its reservoir, supplying downstream areas with more of the cool water that spawning salmon require. In addition, hundreds of millions of dollars have been spent otherwise improving Sacramento River habitat.

But it's doubtful that any amount of effort or money can restore the salmon's world. I didn't fully understand this until I visited the most altered ecosystem of all, the one environmentalists are most likely to lament when discussing the king. It's where ocean and river meet: the vast and troubled estuary at the Sacramento's mouth, through which almost all the river's wild-born salmon pass en route to the Pacific. The former 400,000-acre tidal marsh is California's main water hub, a place both tamed beyond recognition and perilous for salmon in new ways, full of obstacles far more challenging than mere rapids.

Just east of San Francisco Bay, the Sacramento-San Joaquin Delta stretches 50 miles south of Sacramento and some 25 miles west. Part of the largest estuary on North America's Pacific Coast, the delta was once a marshy haven of cattails and bulrushes. Juvenile salmon from both the Sacramento and San Joaquin rivers (which converge in the delta) used it as a kind of staging ground, tarrying in its shallows before going out to sea.

But 150 years and 1,100 miles of man-made levees later, the wetlands have been transformed. During the gold rush, they were drained and converted into a web of farming islands with winding channels in between. Ninety-five percent of the original marsh is gone, and what remains is the epitome of an artificial landscape, so squarely under civilization's thumb that it's almost impossible to imagine it otherwise. The islands—many of them ten feet or more below sea level due to soil decomposition—are a patchwork of crops and alien species: palm trees, European sycamores, Himalayan blackberry bushes, spindly grapevines propped up on sticks, extensive plantings of Bartlett pear trees and fields of lawn turf as green and smooth as a pool table. At times the air suddenly smells of licorice—wild fennel, another invasive species. Go around a levy bend and there might be a beached World War II landing craft used by a local duck-hunting club, a sign for brand-new mansion developments "Coming Soon" or the pink explosion of a garden-variety rosebush.

The waterways surrounding these islands are about as hospitable to salmon as drainage ditches. The remaining marshland teems with nonnative species, many of them ravenous stowaways from the cargo ships of nearby San Francisco Bay. Brazilian waterweed, an aquarium favorite, clogs the sloughs and retains sediments, making the water clearer and juvenile fish easier to spot: predators like largemouth bass—introduced as a sport fish more than a century ago—lie in wait. Upriver farms release potentially poisonous pesticides and herbicides. Wastewater from the Sacramento area, with its ballooning population, also seeps into the delta, and scientists are increasingly suspicious that ammonia from human sewage interrupts the seasonal cycle of phytoplankton blooms at the base of the food chain.

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About Abigail Tucker

A frequent contributor to Smithsonian, Abigail Tucker is writing a book about the house cat.

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