2013: One of the Worst Years on Record for Bay-Delta Fish

2013 was the second worst year on record for the endangered Delta smelt. | Photo: USFWS/Flickr/Creative Commons License

According to the results of an annual state survey of fish populations in the San Francisco Bay and Sacramento Delta estuary, 2013 was a really bad year for a number of important estuary fish species. That bad year continues a decade-long collapse of fish populations throughout California's largest wetland ecosystem. And a major sportfishing group says increased water diversion for urban and farm use is to blame.

The California Department of Fish and Wildlife's "Fall Midwater Trawl 2013 Annual Fish Abundance Summary," part of an annual assessment of fish numbers CDFW has conducted since 1967, turned up the second lowest numbers of Delta smelt and American shad since the surveys began. 2013 numbers for striped bass, threadfin shad, and longfin smelt were the third, fifth, and eighth-lowest on record, respectively.

The low counts continue a pattern of apparent population collapse that began for most of the species in the first years of the 21st Century. The Delta smelt has been listed as a Federally Threatened species since 1993, and was added to the state Endangered list in 2010.

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The related longfin smelt's population in San Francisco Bay was low enough during the 1990s to prompt environmental groups to petition that the species be listed as Endangered in 1992. That petition was unsuccessful. After numbers rebounded for some years in the late 1990s, the longfin smelt's population crashed again in 2001. The shad and bass species surveyed are introduced exotics, and their presence in the Bay and Delta does pose a threat to some native species. Their decline, however, does offer an indication that the Bay and Delta is becoming a less hospitable place for pelagic fish.

The decline across the board coincides with record diversions from the Sacramento River and its tributaries to feed California's increasingly thirsty aqueducts, which caused such steep declines in the number of an economically important California fish -- chinook salmon -- that the state's salmon fishery went through an unprecedented closure in 2008 and 2009.

The correlation between increased diversions and fish population crashes hasn't been lost on advocates for California's fish.

"Excessive water diversions from the Delta by the State and Federal Projects and the failure of state agencies to enforce water quality standards have created an extended fish drought that can only be characterized as a biological holocaust," said Bill Jennings, Executive Director of the California Sportfishing Protection Alliance (CSPA). "And the same agencies that orchestrated and chaperoned this biological meltdown are not only proposing a scheme to divert massive quantities of fresh water flows via tunnels under the Delta... but they ask us to trust them to build the tunnels now and figure out how to operate them later."

The tunnels in question would be the centerpiece of the Bay Delta Conservation Plan (BDCP), and would be capable of carrying the entire summer flow of the Sacramento River past its natural outflow to aqueduct intakes near Tracy.

The project's proponents maintain that the tunnels would not be used at their full capacity when doing so would reduce river levels downstream below levels safe for wild fish. Wildlife advocates like Jennings are skeptical, suggesting that the agencies and irrigation districts pushing for the expensive projects probably wouldn't do so unless it meant more water coming their way -- leaving less for the Bay and Delta.

"BDCP proponents are not going to spend some $67 billion to receive the same or less water and reduced outflow for an estuary already hemorrhaging from a lack of water is a death sentence," said Jennings. "Given the agencies' abysmal track record, there can be no trust and no tunnels until Jerry Brown takes affirmative steps to end his fish drought."

For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.

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