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From mighty sturgeon to tiny smelt, California's native fish are in trouble, under pressure from a variety of causes including drought, habitat loss and diversion of water for human uses, and climate change. A from Professor Andrew Rypel and Distinguished Professor emeritus Peter Moyle at the ²»Á¼Ñо¿Ëù Center for Watershed Sciences highlights some examples. 

"It’s an odd, disturbing feeling – watching populations of native fish species collapse and then disappear. Sometimes it happens quickly, other times it’s a series of slowstep change events. The end result is the same though – smaller populations, extinctions, less biodiversity. We put up a little fight, and occasionally have moderate success. But by and large, the overall trend is down, the pace of change quickening, and it is relentless," Rypel and Moyle write. 

• California White Sturgeon: Until quite recently regarded as a management success story, the white sturgeon is on its way to listing under the California Endangered Species Act, following a massive decline in numbers.
• Longfin Smelt: These tiny fish have been proposed for listing under the U.S. Endangered Species Act, hit by many of the same problems as the related Delta smelt, which is now effectively extinct in the wild.
• Spring run Chinook salmon: "The collapse of wild spring-run Chinook salmon in the Sacramento Basin has been swift and scary," Rypel and Moyle write. Once numbering in the hundreds of thousands, the spring-run chinook now hold in in just three creeks with numbers in the double digits. 
• Speckled Dace: Three subspecies of these fish are known in California, some restricted to a single stream. 

Freshwater biodiversity is collapsing worldwide, and 83 percent of California's native fish species are at risk of extinction, Rypel and Moyle write. These extinctions show our inability, despite years of effort, to protect ecosystems. The loss of fish such as sturgeon and salmon impacts indigenous peoples and has knock-on environmental effects. 

"Every time a species is listed, or worse, goes extinct, it is another indicator of how the environment in which we live is becoming less suitable for people and fish overall," Rypel and Moyle write.

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