On a mild day between rainstorms in mid-December, wildlife biologists outfitted in rubber boots and orange lifejackets load drum after drum of precious cargo onto a small boat docked in Rio Vista, a town on the Sacramento River in the Sacramento-San Joaquin Delta. There is little fanfare but the occasion is nonetheless momentous. The shiny silver drums contain thousands of Delta smelt — finger-size imperiled fish unique to the Delta — that were raised in a conservation hatchery. Today marks the inaugural release of captive smelt into the cold, murky waters of their native home.
“For the first time, we’re seeing if it’s possible for hatchery-raised Delta smelt to be released into the wild, survive, and successfully reproduce,” says Katherine Sun, a biologist with the U.S. Fish and Wildlife Service (USFWS) who co-leads the multi-agency effort that also includes the California Department of Fish and Wildlife, the California Department of Water Resources, the U.S. Bureau of Reclamation, the U.S. Geological Survey, and UC Davis.
Delta smelt were once plentiful. “You could pull up a net and expect to see a good handful of them,” Sun says in a recent USFWS Fish of the Week! podcast. Added to federal and state endangered species lists in 1993, the Delta smelt is now close to extinction. “We’re talking in the hundreds,” Sun continues.
Hatchery-raised Delta smelt staged for loading in barrels before traveling by truck and boat to the waters of their genetic origin. Photo: USFWS
This slender, nearly translucent fish may be tiny and all but gone, yet its influence on California water is huge. Much of the water flowing through the Delta is pumped south, providing drinking water for 25 million people and irrigating nearly 4.5 million acres of Central Valley farmland. Protections for Delta smelt include periodically curtailing these exports to keep the fish from being sucked toward and even into the pumps.
“The Delta smelt … has become a flashpoint for significant resentment, frustration, and lawsuits,” note the authors of a September 2021 commentary in the journal Environmental Law Reporter, including Karrigan Börk, an associate director at the UC Davis Center for Watershed Sciences.
Tensions over the water supply could be eased by reversing the Delta smelt’s decline, giving wildlife and water managers alike a shared interest in the welfare of this at-risk species.
The immediate intent of the Rio Vista hatchery smelt release is not to bolster the barely-there wild population, but rather to determine the best way to get these captive fish into the Delta and thereby optimize future releases. It’s taken decades to get to this point.
“Some may say it’s too late but I’m glad we’re finally putting the fish out,” says Tien-Chieh Hung, who directs the UC Davis Fish Conservation and Culture Laboratory that raises hatchery smelt.
Making sure conditions in the water are perfect for release. Photo: USFWS
The conservation hatchery began figuring out how to breed and raise Delta smelt in captivity in the mid-1990s, soon after the fish was formally listed under the federal Endangered Species Act. To keep hatchery fish as similar to the wild population as possible, the captive population is managed to preserve genetic diversity, aided by an annual influx of up to 100 wild-caught smelt.
It’s getting hard to reach that quota. The hatchery last caught its full allotment of wild Delta smelt in the winter of 2017-2018. Over the next two winters, the catch dipped to 28 and then rebounded to 93. Last winter, the hatchery caught just two fish. “We’re struggling,” Hung says. “We’re still catching some but it takes much more effort to find them.”
The hatchery raised 40,000 smelt for this winter’s releases near Rio Vista, with 12,800 set free in the mid-December kickoff. Winter is a good time to put hatchery smelt in the wild because this is when they start migrating upstream toward the freshwater where they spawn. In summer the young smelt then migrate downstream to the brackish waters where they grow up.
Delta smelt are so sensitive to human handling that the researchers think it will take three years to figure out the best way to move and release them. For example, the team has learned that the fish need to be transported in round containers. “They’re relatively weak swimmers,” Sun explains in the podcast. “Delta smelt have been known to get stuck in corners, they get stressed out, and they die.”
This winter the researchers are comparing two ways of releasing this fragile species from the transportation drums: letting the smelt swim straight into the Delta immediately versus holding them in cages for up to three days so they can get used to their new home. The process is as gentle as possible. One by one, the drums are carefully hoisted and lowered into the water, pried opened, and gradually tipped to let Delta water in and hatchery smelt out. The small fish vanish immediately into the turbid water that helps them hide from predators.
Hatchery Delta smelt release to wild December 2021. Video: USFWS
For now, the goal is simply to see if the hatchery smelt can stay alive in the Delta. Future goals include seeing if hatchery smelt will breed in the wild, and if they can survive when released in other parts of the Delta such as the Sacramento Deep Water Ship Channel, the Cache Slough Complex, and Suisun Marsh. The eventual plan is to use hatchery Delta smelt to boost the wild population.
Hatchery fish alone will not be enough to save the smelt, however, because the Delta ecosystem is severely degraded. “Habitat restoration is a huge part of the effort,” says Ken Paglia, a California Department of Fish and Wildlife spokesman. “You don’t want to release fish into an ecosystem that isn’t doing well.”
Delta smelt require water that is cool and neither too salty nor too clear, making them dependent on freshwater from the rivers that flow into the Delta and also sensitive to the vast volumes of water exported south for drinking and irrigation. Another threat to these fish is that the Delta produces far less of the food they eat. The early 2000s saw a precipitous decline of Delta smelt that coincided with a drop in zooplankton, minuscule aquatic creatures that make perfect fish food.
Simultaneous declines were observed in several other open-water (pelagic) fish in the Delta, including the threatened longfin smelt and the non-native striped bass. This alarming multi-species decline sparked regular surveys for these pelagic fish, which serve as indicators of ecosystem health. While none of these fish have rebounded, longfin smelt are still breeding in the South Bayand striped bass are still breeding in Suisun Marsh.
Smelt release into natural habitat. Photo: USFWS
Biologists hope the released hatchery Delta smelt will benefit from habitat restoration in the Delta, including tidal marshes and floodplains where zooplankton thrive. Previous experiments with captive smelt in cages in restored habitat confirm that these sites produce plenty of food for fish.
The survey crews that track Delta smelt and the other indicator pelagic fish will be able to distinguish smelt born in the hatchery from those born in the wild at a glance. The conservation hatchery marked every single one of the captive-born fish by clipping their adipose fins, small flaps on the back that don’t grow back. Some of the hatchery smelt also have silicone tags injected under their see-through skin. “It makes a one-centimeter line under the dorsal fin and you can vary the color,” Hung explains. For hatchery smelt released this winter, these subcutaneous tags are red.
Peter Moyle, a UC Davis biologist who witnessed the Delta smelt’s decline firsthand over more than half a century of studying them, is skeptical of the prospects for hatchery fish in the Delta: “If the wild smelt have not made it, what makes them think there’s good habitat now?” He also worries that hatchery smelt will lose the capacity to live in the wild. “The longer you keep them in captivity, the more domesticated they become,” he says. “We’re in a desperate situation with smelt.”
Rather than releasing hatchery smelt directly into the Delta, Moyle favors first putting them in ponds on Delta islands. This intermediate step could help captive smelt become accustomed to the natural world. That said, he agrees that taking action to save the Delta smelt is essential. “No matter what we try to do, it’s risky,” Moyle says. “But the alternative is for the smelt to go extinct.”
And there are signs of hope for hatchery smelt in the Delta. Since the first batch was let loose, survey crews have spotted more than a dozen swimming in the lower Sacramento River. “This means they weren’t just a buffet for predators and that they’re moving in the Delta,” Hung says. “They’re out there and hopefully doing well.”
Top Photo: Loading smelt for mid-channel release in December 2021. Photo: USFWS
Robin Meadows is an independent science journalist in the San Francisco Bay Area. She’s a water reporter at Maven's Notebook, a California water news site, and contributor to Chemical & Engineering News, Ka Pili Kai, KneeDeep Times, and Scientific American. Robin is also a Pulitzer Center grantee, an Institute for Journalism & Natural Resources fellow, a contributor to The Craft of Science Writing, a mentor with The Open Notebook, and a UC Santa Cruz Science Communication Program graduate. Find her on Tumblr and Twitter.
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Hothouse Earth
By Ariel Rubissow Okamoto
Photo by Megan Nguyen
Nothing could be stranger than sitting in the dark with thousands of suits and heels, watching a parade of promises to decarbonize from companies and countries large and small, reeling from the beauties of big screen rainforests and indigenous necklaces, and getting all choked up.
It was day two of the September 2018 Global Climate Action Summit in San Francisco when I felt it.
At first I wondered if I was simply starstruck. Most of us labor away trying to fix one small corner of the planet or another without seeing the likes of Harrison Ford, Al Gore, Michael Bloomberg, Van Jones, Jerry Brown – or the ministers or mayors of dozens of cities and countries – in person, on stage and at times angry enough to spit. And between these luminaries a steady stream of CEOs, corporate sustainability officers, and pension fund managers promising percentages of renewables and profits in their portfolios dedicated to the climate cause by 2020-2050.
I tried to give every speaker my full attention: the young man of Vuntut Gwichin heritage from the edge of the Yukon’s Arctic National Wildlife Refuge who pleaded with us not to enter his sacred lands with our drills and dependencies; all the women – swathed in bright patterns and head-scarfs – who kept punching their hearts. “My uncle in Uganda would take 129 years to emit the same amount of carbon as an American would in one year,” said Oxfam’s Winnie Byanyima.
“Our janitors are shutting off the lights you leave on,” said Aida Cardenas, speaking about the frontline workers she trains, mostly immigrants, who are excited to be part of climate change solutions in their new country.
The men on the stage, strutting about in feathers and pinstripes, spoke of hopes and dreams, money and power. “The notion that you can either do good or do well is a myth we have to collectively bust,” said New Jersey Governor Phil Murphy whose state is investing heavily in offshore wind farms.
“Climate change isn’t just about risks, it’s about opportunities,” said Blackrock sustainable investment manager Brian Deese.
But it wasn’t all these fine speeches that started the butterflies. Halfway through the second day of testimonials, it was a slight white-haired woman wrapped in an azure pashmina that pricked my tears. One minute she was on the silver screen with Alec Baldwin and the next she taking a seat on stage. She talked about trees. How trees can solve 30% of our carbon reduction problem. How we have to stop whacking them back in the Amazon and start planting them everywhere else. I couldn’t help thinking of Dr. Seuss and his truffala trees. Jane Goodall, over 80, is as fierce as my Lorax. Or my daughter’s Avatar.
Analyzing my take home feeling from the event I realized it wasn’t the usual fear – killer storms, tidal waves, no food for my kids to eat on a half-baked planet – nor a newfound sense of hope – I’ve always thought nature will get along just fine without us. What I felt was relief. People were actually doing something. Doing a lot. And there was so much more we could do.
As we all pumped fists in the dark, as the presentations went on and on and on because so many people and businesses and countries wanted to STEP UP, I realized how swayed I had let myself be by the doomsday news mill.
“We must be like the river, “ said a boy from Bangladesh named Risalat Khan, who had noticed our Sierra watersheds from the plane. “We must cut through the mountain of obstacles. Let’s be the river!”
Or as Harrison Ford less poetically put it: “Let’s turn off our phones and roll up our sleeves and kick this monster’s ass.”
4th California Climate Change Assessment Blues
by Isaac Pearlman
Since California’s last state-led climate change assessment in 2012, the Golden State has experienced a litany of natural disasters. This includes four years of severe drought from 2012 to 2016, an almost non-existent Sierra Nevada snowpack in 2014-2015 costing $2.1 billion in economic losses, widespread Bay Area flooding from winter 2017 storms, and extremely large and damaging wildfires culminating with this year’s Mendocino Complex fire achieving the dubious distinction of the largest in state history. California’s most recent climate assessment, released August 27th, predicts that for the state and the Bay Area, we can expect even more in the future.
The California state government first began assessing climate impacts formally in 2006, due to an executive order by Governor Schwarzenegger. California’s latest iteration and its fourth overall, includes a dizzying array of 44 technical reports; three topical studies on climate justice, tribal and indigenous communities, and the coast and ocean; as well as nine region-specific analyses.
The results are alarming for our state’s future: an estimated four to five feet of sea level rise and loss of one to two-thirds of Southern California beaches by 2100, a 50 percent increase in wildfires over 25,000 acres, stronger and longer heat waves, and infrastructure like airports, wastewater treatment plants, rail and roadways increasingly likely to suffer flooding.
For the first time, California’s latest assessment dives into climate consequences on a regional level. Academics representing nine California regions spearheaded research and summarized the best available science on the variable heat, rain, flooding and extreme event consequences for their areas. For example, the highest local rate of sea level rise in the state is at the rapidly subsiding Humboldt Bay. In San Diego county, the most biodiverse in all of California, preserving its many fragile and endangered species is an urgent priority. Francesca Hopkins from UC Riverside found that the highest rate of childhood asthma in the state isn’t an urban smog-filled city but in the Imperial Valley, where toxic dust from Salton Sea disaster chokes communities – and will only become worse as higher temperatures and less water due to climate change dry and brittle the area.
According to the Bay Area Regional Report, since 1950 the Bay Area has already increased in temperature by 1.7 degrees Fahrenheit and local sea level is eight inches higher than it was one hundred years ago. Future climate will render the Bay Area less suitable for our evergreen redwood and fir forests, and more favorable for tolerant chaparral shrub land. The region’s seven million people and $750 billion economy (almost one-third of California’s total) is predicted to be increasingly beset by more “boom and bust” irregular wet and very dry years, punctuated by increasingly intense and damaging storms.
Unsurprisingly, according to the report the Bay Area’s intensifying housing and equity problems have a multiplier affect with climate change. As Bay Area housing spreads further north, south, and inland the result is higher transportation and energy needs for those with the fewest resources available to afford them; and acute disparity in climate vulnerability across Bay Area communities and populations.
“All Californians will likely endure more illness and be at greater risk of early death because of climate change,” bluntly states the statewide summary brochure for California’s climate assessment. “[However] vulnerable populations that already experience the greatest adverse health impacts will be disproportionately affected.”
“We’re much better at being reactive to a disaster than planning ahead,” said UC Berkeley professor and contributing author David Ackerly at a California Adaptation Forum panel in Sacramento on August 27th. “And it is vulnerable communities that suffer from those disasters. How much human suffering has to happen before it triggers the next round of activity?”
The assessment’s data is publicly available online at “Cal-adapt,” where Californians can explore projected impacts for their neighborhoods, towns, and regions.
The results are alarming for our state’s future: an estimated four to five feet of sea level rise and loss of one to two-thirds of Southern California beaches by 2100, a 50 percent increase in wildfires over 25,000 acres, stronger and longer heat waves, and infrastructure like airports, wastewater treatment plants, rail and roadways increasingly likely to suffer flooding.