The Bay’s white sturgeon—huge, slow-to-reproduce “living fossils” that have hardly changed over their approximately 200 million years on Earth—are now facing such peril that the state of California has closed fishing for them under emergency regulations while it considers listing them as a threatened species.
White sturgeon lurk in the murky bottom of San Francisco Bay and the Delta, stealthily making their way upriver to spawn and slurping up clams. Of San Francisco Bay’s two sturgeon species, white sturgeon are the homebodies (in contrast to anadromous green sturgeon, which spend much of their lives at sea ^(https://www.blogquicker.com/goto/https://baynature.org/2022/12/08/how-a-sturgeon-surgeon-tracks-the-bays-living-fossils/)). But adult white sturgeon numbers have been in decline for two decades, says UC Davis fish biologist Andrea Schreier.
“Changes to the Bay-Delta system and changes to our climate are happening too quickly for them,” Schreier says.
Two threats have long been known: overfishing and a lack of the plentiful freshwater sturgeon need to spawn. In 2022, a new threat emerged when a devastating Bay-wide harmful algae bloom killed at least 800 sturgeon—with many more dead fish presumably uncounted ^(https://www.blogquicker.com/goto/https://baynature.org/2022/12/21/after-2022s-fatal-algal-bloom-scientists-fear-the-bays-sturgeon-could-go-extinct/).
On July 12, the California Fish and Game Commission’s five governor-appointed members voted unanimously to make white sturgeon official candidates for threatened status under the California Endangered Species Act (CESA). The commission’s decision came in response to a November 2023 petition ^(https://www.blogquicker.com/goto/https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=223741&inline) submitted by a coalition of organizations, including San Francisco Baykeeper, Restore the Delta, the Bay Institute, and the California Sportfishing Protection Alliance, an angler advocacy group. A listing for white sturgeon could be a major blow to the recreational fishing industry, especially if white sturgeon fishing is banned altogether. And it could further complicate the intensely fought-over diversion of water from the Sacramento-San Joaquin Delta for agriculture, drinking water, and other uses. The coalition is also petitioning for a federal Endangered Species Act listing.
The CESA review process will take at least a year. During this time, “it will be illegal to fish for sturgeon,” says John Kelly, biologist and sturgeon coordinator at the California Department of Fish and Wildlife (CDFW), which will conduct the scientific review. Ultimately, the listing decision is up to the Fish and Game Commission, which is responsible for implementing and enforcing regulations for game conservation.
Candidate species receive full protection in the meantime. The Commission requested that the CDFW evaluate options for keeping the fishery open in some capacity by mid-August, such as allowing catch and release. Any other activities that put white sturgeon at risk, or that could impact the long term viability of the species, will be required to go through CESA permitting processes to mitigate their effect on the species.
“There is a very strong connection between increasing water development and decline of the white sturgeon,” says Jon Rosenfield, science director for San Francisco Baykeeper, one of the petitioners. “We need to fix these problems, and if we don’t, we should consider these fish as harbingers of worse outcomes to come from unsustainable water management in California.”
Potentially solvable: the overfishing problem
White sturgeon (Acipenser transmontanus), the largest freshwater fish found in North America, can grow up to 10 feet long and live as long as a century—and they and other sturgeons are in trouble all around the world. Of 27 species, 26 are considered at risk of extinction by the International Union for Conservation of Nature, with the 27th fully extinct.
White sturgeon take over a decade to reach reproductive maturity, and will spawn only in years with plenty of water. They may journey hundreds of miles from the Bay up the Sacramento and San Joaquin rivers to spawn, making them uniquely susceptible to habitat loss and other human impacts.
They are also an iconic target species for Delta anglers—being enormous and athletic, strong enough to yank fishing lines and drag boats around when caught. Researchers contracted by CDFW published a study in 2019 (three years before the big harmful algal bloom) concluding that harvest rates were too high, and recommended a harvest rate of about 3 percent annually to stabilize the population.
“Harvest rates have been at a level that’s considered unsustainable for sturgeon,” says Schreier. “It’s not the only threat. But it’s a threat that is more easily managed than flow rates.”
At a public meeting about white sturgeon’s CESA candidacy, some anglers were concerned about potential economic impacts to fishing guides, captains, boats, and marinas. One article on the Nor-Cal Guides and Sportsmen’s Association website ^(https://www.blogquicker.com/goto/https://ncgasa.org/2024/06/28/fisheries-expert-fish-game-commissions-move-to-list-white-sturgeon-is-a-red-herring/) described the fishing closure as unfairly punishing anglers for a problem largely caused by excessive Delta water diversions. Upset comments about the sturgeon ban on Sturgeon Hunters, a public Facebook group, included anglers lamenting “the end of an era,” demanding refunds for sturgeon tags, and questioning whether the population is really threatened.
Petitioners advocated for a catch-and-release fishery, which would allow for the thrills (and the business) without the kills. They look to the example set by Canada, which restricted fishing to catch-and-release only in British Columbia’s Fraser River. There, the threatened fish population grew while continuing to sustain a recreational fishery.
“You can have a very profitable, economically viable catch and release fishery for white sturgeon, even when the population is threatened,” says Rosenfield.
The HABs problem may be trickier
But even if the overfishing stops, white sturgeon will still be at risk of death from harmful algal blooms.
“The 2022 HAB was a big wake-up call,” says Schreier. “If something of that magnitude happens again, that could be really devastating for the population.”
Harmful algae blooms are fueled by nitrogen and phosphorus entering the Bay and Delta through wastewater treatment plants, as well as agricultural and urban runoff. Reducing those nutrient sources would require expensive wastewater plant upgrades or major reductions in fertilizer use, as Bay Nature has reported ^(https://www.blogquicker.com/goto/https://baynature.org/2023/07/10/can-we-prevent-another-algaepocalypse-in-the-bay/).
“There are going to be more HABs in the San Francisco estuary, unless something significantly changes with the nutrient inputs,” says Schreier.
That’s not hypothetical. Tom Cannon, a fish biologist who is on the advisory board of the California Sportfishing Protection Alliance, wrote in a blog post this week ^(https://www.blogquicker.com/goto/https://calsport.org/fisheriesblog/?p=4686) that a recent heat wave is making Bay conditions worse for sturgeon this year than in 2022 or 2023. “I am concerned that conditions are building for yet another sturgeon die-off this summer,” he wrote.
Despite the risks these blooms pose, there still remains a Bay-sized gap in jurisdiction over HABs in the Bay, as Bay Nature reported last year ^(https://www.blogquicker.com/goto/https://baynature.org/2023/08/07/just-in-time-for-algae-season-a-new-satellite-map-offers-glimpses-of-bay-blooms/). No single state agency is specifically responsible for responding to harmful algal bloom incidents in saltwater, and no one agency is responsible for monitoring the Bay for the phytoplankton that causes such blooms.
Trickiest of all: California water supply issues
The stickiest threat to white sturgeon, petitioners claim, is a lack of freshwater flow from the Sacramento and San Joaquin rivers, through the Delta, and into the Bay. The San Francisco Bay watershed is the only place in California where white sturgeon spawn. Adults only migrate upriver when flow is high, and in dry years white sturgeon do not spawn at all. Even when there is enough flow to trigger a spawning migration, it isn’t necessarily enough for juveniles to survive the journey back down to the Bay.
But diversion and storage of Delta water is deeply political. Currently, over half the flow from Central Valley rivers is diverted for agriculture and drinking water. State water contractors opposed the potential listing, concerned about increased CESA regulations affecting major state and federal water projects, which provide water to 29 million California residents and 1.9 million acres of farmland.
The State Water Contractors, a coalition of water agencies, and the San Luis & Delta-Mendota Water Authority argued in a letter to the Commission that white sturgeon should not be listed because current regulations sufficiently protect the fish and the petitioners’ data are flawed ^(https://www.blogquicker.com/goto/https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=223741&inline). According to the letter, the petition “ignores evidence that the white sturgeon adult population far exceeds the recovery standard for green sturgeon, a very similar species,” and that “CDFW estimates of white sturgeon abundance show that the population has been stable from approximately 2008 to 2022,” while the petition shows a decline from a peak sturgeon population in the 1980s. “Any comparison of the white sturgeon population to the highest abundance time-period would result in a downward trend,” the letter concludes.
Regardless of whether a CESA listing secures more water flow to help sturgeon spawn, it could boost white sturgeon conservation in other ways. Schreier hopes that the increased attention might lead to more funding for scientists to pinpoint the most crucial bottlenecks in sturgeon migration, spawning, and juvenile survival. Another scientific goal is to improve monitoring and population surveys and find out which threats cause the most adult sturgeon deaths, be it vessel strikes, overfishing, harmful algae blooms, or otherwise.
Currently, the CDFW is testing new techniques to capture and tag sturgeon to gather more detailed population data. But they will have to be patient; it takes sturgeon around 15 years to become mature enough to reproduce—meaning it will likely take over a decade to see the results of whatever new regulations or interventions come their way.
“There’s a lot of people who want to see a healthy sturgeon population,” says Schreier. “If we work together and support sensible conservation and management efforts, I think we can achieve that.”
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