A quote in the story from California’s leading authority on native fish, Peter Moyle of the University of California at Davis, gets straight to the point: “We’re going to be losing most of our salmon and steelhead if things continue.” The die-off of Sacramento-San Joaquin Delta smelt, Moyle said in the story, is so massive that all that’s left is “the last of the last.”
It gets worse. The same is starting to happen in Oregon and Washington, where moist climates are giving way to some of the worst drought conditions those states have experienced. I wrote about what falling water levels are doing to Pacific Northwest salmon in a story last month.
Oregon and Washington have closed dozens of recreational and commercial fishing spots. The U.S. Fish and Wildlife Service trucked 160,000 salmon 100 miles from a hatchery in central Oregon to a cooler part of the Columbia River.
That mirrored an effort south of the state border in California, where state officials trucked 30 million young chinook salmon to the bay from several hatcheries in a dozen 35,000-gallon water tankers. The delta is so dry that the fish would die trying to migrate 90 miles from the San Joaquin River in the Sacramento area to the San Francisco Bay.
It’s not just that the water is low. With temperatures in all three states rising and water levels falling, the shallower waters warms sooner. It’s a triple whammy for the fish. Warm water carries more diseases that attack fish that prefer waters cooler than 60 degrees Fahrenheit. Adult and young salmon get hit coming and going in their migrations in rivers to and from the ocean.
An estimated quarter-million salmon, more than half of the spring spawning run up the Columbia River, perished, probably because of a disease that thrives in warm water and causes gill rot, officials said.
Salmon and other fish usually take a beating when humans develop in and around their habitats. Dams and other water diversions have blocked them from historic spawning grounds on the Pacific and Atlantic coasts.
“The bleakest, most dire outcome is if this drought is sustained for a couple more years like California,” said Greg McMillan, science and conservation director for Oregon’s Deschutes River Alliance. Some populations “could go extinct,” he said.
After hatching, some salmon young head directly to the ocean and, likely this year, straight to their doom as warm weather diseases can cause gill rot. Other young salmon shelter in the places where they hatch, which is more worrisome, because higher temperatures have warmed their habitat. It’s a better environment for disease, and also the plant life the fish feed on can’t grow.
“Those fish trying to live in the fresh water for the year are gone, toast,” said Teresa Scott, drought coordinator for Washington state’s Department of Fish and Wildlife. “We’re having impacts on fish right now, but that won’t be felt until adults don’t show up in future years.”