The San Francisco Chronicle had a solid examination today of the decline of the Chinook salmon, a fish found in the Sacramento-San Joaquin River Delta.

The decline threatens to close salmon fishing season along the entire Pacific coast this year and could spell trouble for drinking water exports from the delta, a major source of San Diego’s supply. The Chronicle explains what effect the pumps that send water from the delta to Southern California may have had on the fish:

The chinook salmon — born in the rivers, growing in the bay and ocean, and returning to home rivers to spawn — need two essential conditions early in life to prosper: safe passage through the rivers to the bay and lots of seafood to eat once they reach the ocean.

Yet, the Sacramento River run of salmon that was expected to fill fish markets in May didn’t find those life-sustaining conditions. And some scientists say that’s the likeliest explanation for why the number of returning spawners plummeted last fall to roughly 90,000, about 10 percent of the peak reached just a few years ago.

The devastating one-two punch happened as the water projects in the Sacramento-San Joaquin River Delta pumped record amounts of snowmelt and rainwater to farms and cities in Southern California, degrading the salmon’s habitat. And once the chinook reached the ocean, they couldn’t find the food they needed to survive where and when they needed it.

We recently examined the decline of another fish found in the delta, the longfin smelt, and the problems that may cause for water supplies.


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