By Alastair Bland
Another fish native to the San Francisco Bay estuary may be joining the queue filing toward extinction. That’s the fear of a coalition of environmental groups that have petitioned the California Fish and Game Commission to list the white sturgeon, one of the largest freshwater fishes in the world, as a threatened species under California’s Endangered Species Act.
At its June 19th meeting in Mammoth Lakes, the commission responded to the petition by calling for a full status review of the species, which could lead to a formal listing. The decision gives the white sturgeon full protected status while the review is underway. This will mean a pause on recreational sturgeon fishing—popular in the Bay and Delta—and more careful operation of water pumping stations in the south Delta.
Water supply proponents have publicly opposed the review and feel the impacts it will have on water supply operations are unfair when the species is merely a candidate for listing.
“How can the burden of proof [on the petitioners] be so low for making such an impactful decision?” says Chandra Chilmakuri, assistant general manager for water policy with the State Water Contractors, a coalition of farm groups and water agencies. The group has argued that the white sturgeon population is not in decline, and they insist that existing water export systems are guided by strict environmental regulations.
“Our operations are already protective,” he says.
The status review—to be led by the California Department of Fish and Wildlife over the next 12 to 18 months—could complicate the construction of the much-anticipated Delta tunnel and the Sites Reservoir. That’s because white sturgeon, to successfully reproduce, require the same peak flows that these proposed facilities would be designed to capture.
“That may pose a challenge to a species like white sturgeon, where you’re clipping those high flows, because those are the exact kinds of years that are good for white sturgeon,” says Andrew Rypel, a professor of fish biology at UC Davis who believes enhanced protections for the species are overdue.
The petition—submitted in November 2023 by The Bay Institute, Restore the Delta, the California Sportfishing Protection Alliance, and San Francisco Baykeeper—argued that the population is at record low levels and may still be declining. “[W]ithout additional protections afforded to species listed under the Endangered Species Act (ESA), the California White Sturgeon is increasingly likely to become endangered in the near future,” the petitioners, led by Baykeeper’s science director Jon Rosenfield, wrote.
Officials estimate that the state’s population of white sturgeon has plunged in the past 150 years, from the ballpark count of 200,000 adult fish to 33,000 today. The fish of today are also much smaller on average than the white sturgeon of last century and before. Threats include the disruption of the estuary’s natural flow cycles by dams, levees, and pumping stations, water pollution and algal blooms, and pressure from both poaching and legal sport fishing.
Sport anglers, who submitted a letter to the commission opposing the status review, have denied that recreational take has a significant impact on the species.
Rypel disagrees. He says licensed anglers probably remove about 4% of the adult population each year—double what he says would be a sustainable level for the slow-growing sturgeon. Currently, anglers are allowed to keep one sturgeon per year measuring between 42 and 48 inches—what’s called the legal size “slot limit.” In spite of these strict regulations, too many sturgeon are dying in the fishery. It takes two to three years for a sturgeon to grow through that size range, and Rypel says fishing pressure is intense enough that few white sturgeon survive past it. A 48-inch white sturgeon, typically, is a mere 40 pounds and about 14 years old—an adolescent in a species that can reach 1,500 pounds, can live more than a century, and has gone unchanged by evolution for tens of millions of years.
There is no question California’s sturgeon have declined in size and population from historic times, and even in recent decades the fishery has lost vigor. In 1983, when fishing regulations were still quite liberal, a sport angler fishing near Benicia caught, killed, and weighed a 468-pound white sturgeon, still the state angling record. Scattered tackle shops in the region invariably have old photos on the walls of fishers hoisting fish weighing 100 pounds and more, which were still relatively common through the 1980s and 90s.
In 2022, concern hit a tipping point after hundreds of adult sturgeon were observed dead during and after a summer toxic algal bloom in San Francisco Bay. The total adult death toll, experts suspect, was in the thousands. Rypel says the event may have killed between 40 and 60 percent of the Bay’s adult white sturgeon.
A less severe but similar event occurred about a year later, further impacting the population and its overall reproductive fecundity.
“[I]t will likely take decades to replace the adult fish lost to this mass mortality event,” Rypel and several colleagues wrote in a blog post from Nov. 2022. The authors, including Andrea Schreier and Peter Moyle of U.C. Davis, likened the 2022 algal bloom to a wildfire that kills a grove of old-growth redwoods, and they recommended imposing a catch-and-release rule for sport fishers.
But a moratorium on harvest is only part of what California’s white sturgeon need, argues Baykeeper’s Rosenfield, who presented the case for listing the species at the recent commission meeting. He says the species’ plight is tightly woven into California’s fabled feuds over water supply and how to allocate the resource, especially water which streams through the Bay-Delta watershed.
In short, he argues, the fish need more of it in the San Francisco Estuary. The simultaneous declines of multiple other species in the ecosystem—notably the Delta smelt and Chinook salmon—suggest a common threat, and that, Rosenfield says, relates to water.
“White sturgeon are the largest North American freshwater fish, Delta smelt are among the smallest North American freshwater fish,” he says. “One lives one year, the other lives 100 years. They don’t have much in common, but the fact that they’re both in decline tells us we’re damaging the entire ecosystem. … They need high river flows.”
His argument follows research showing that, while adult white sturgeon spawn in both dry and wet years, juvenile survival is high only in periods immediately following wet winters and heavy Delta outflow through spring and summer.
Rypel echoes Rosenfield’s claim:
“Most of our native fishes rely on those high-flow years for recruitment, and white sturgeon are the extreme example of that. They only recruit on the highest of flow years.”
Future water projects, Rosenfield and Rypel say, could mute the flow conditions sturgeon need. The Sites Reservoir, proposed for construction in a small basin to the west of the Sacramento River, has been designed and planned on the premise that it will only be filled with surplus water during wet years. The Delta tunnel, in discussion for decades, would also be used to take advantage of high flows. The Voluntary Agreements for the Bay Delta Water Quality Control Plan also propose to divert more water into storage during the wettest years.
But Chilmakuri, at the State Water Contractors, says the gushing wet winters beneficial to sturgeon fill the Central Valley’s rivers with so much water that existing export projects barely dent them. Planned facilities, he adds, will also have a negligible effect.
“Sites and the Delta Conveyance Project together can take about 10,000 cubic feet per second,” he said, observing that average flows in the wettest winters and springs may exceed 100,000.
The water agencies opposing the listing of the white sturgeon note that scientific data suggests the fish’s population has been stable for at least 14 years.
“If the population is self-sustaining, then there’s no need for this protection,” Chilmakuri said.
But Rypel says a massive crash in sturgeon numbers preceded the recent leveling off, and that current numbers do not represent a resilient population.
“The population declined from the 1960s down to some new low-level equilibrium in the 2000s, and it’s been at that low level for a while,” he says. “Then we had the harmful algal bloom.”
That 2022 disaster, which saturated the shoreline breeze with the reek of rotting fish and invertebrates for weeks, motivated the Fish and Game Commission to reduce the annual harvest limit from three white sturgeon to one and shift the slot limit from 40 to 46 inches to the current 42 to 48 inches.
During the June 19 meeting’s public comment period, several anglers and business owners opposed to the listing claimed the sturgeon population is more robust than scientists say. They said the sport fishing industry would suffer from the listing and that more research is needed to direct future management actions.
One angler, Roger Mammon of the California Striped Bass Association, said he voluntarily quit keeping sturgeon decades ago and said a catch-and-release fishery should be encouraged. The commissioners confirmed that a listed finfish species could legally be subject to a targeted catch-and-release sport fishery.
The director of the California Department of Fish and Wildlife Chuck Bonham added that concerns about a threatened listing for the white sturgeon could be a little premature.
“Let’s take the word ‘listing’ out of the discussion,” he said. “The question of whether it’s permanently listed or not only happens a year from now after the department completes an entire status review.”
Rosenfield says the white sturgeon’s decline in what amounts to a geologic second is a clear indicator that they and their habitat need protection as soon as possible.
“They’ve been here for 46 million years,” he said. “White sturgeon have survived unimaginable changes in the climate, in the ocean, rainfall patterns, landscape patterns—they’ve survived everything but us.”
Produced by Estuary News Group for Maven’s Notebook with funding from the Delta Stewardship Council.
