All of these inland threats have conspired to weaken the salmon’s former resilience, says Peter Moyle, a fish biologist at the University of California, Davis. Since Chinook are naturally adapted to variable freshwater and saltwater conditions, they have historically thrived even when rivers or streams were temporarily unfavorable—such as during a drought—as long as ocean conditions were not equally poor. Similarly, an undesirable ocean environment rarely coincided with unfavorable waters inland. But now, thanks to human-induced impacts, both salmon habitats are often in bad shape.
“It’s the one-two punch idea,” Moyle says.
As human populations continue to climb in the West, so does the impact on salmon. “Everything humans do, from a salmon perspective, is not good. They compete for the same resources,” says Robert Lackey, a senior fisheries biologist at the U.S. Environmental Protection Agency. “If people want cheap food, one of the costs is salmon.”
In 2005, the year that NOAA’s Peterson calls “the worst year in the ocean in God knows how long,” a record amount of freshwater was diverted from the Sacramento-San Joaquin River Delta for irrigation and drinking water. Spain, of the fishermen’s federation, believes poor ocean conditions were “the final straw” for salmon that were already stressed by a multitude of other problems.
Spain describes a zigzagging course with an overall downward trend: “Ocean conditions go up and down, but habitat or water availability gradually deteriorate,” he says. The current Chinook situation may be at a low point in that pattern, ready for an upswing. “And over a period of years,” Spain adds, “every time it goes up people tend to say ‘Oh, we solved the problem’ without realizing that ocean conditions will change and then [salmon populations] will go down deeper if we haven’t really solved those problems inland.”
While the multiple and interacting factors are difficult to tease apart, there seems to be agreement that both the ocean and freshwater systems will be found guilty. A governmental panel, of which Bill Peterson is a member, is attempting to narrow down a list of nearly 50 possible reasons for the Sacramento River Chinook collapse. “Since the returns were so, so, so low,” Peterson concedes, “there must be something else going on other than the ocean.” Future generations of salmon, and dormant fishing poles, anxiously await the verdict.
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