Bay Fish Still Not Good Eating

Native Species



17
Jun

Bay Fish Still Not Good Eating

After decades of efforts to clean up San Francisco Bay, its fish still carry a toxic load that makes them unfit for human consumption. A new Regional Monitoring Program (RMP) report on its 2019 sport fish survey contains some positive news: an overall decline in polybrominated diphenyl ethers (PBDE), hopeful trends in polychlorinated biphenyls (PCBs) and dioxin, and continued low selenium levels. But no downward trend was found for mercury. Then there are per- and polyfluoroalkyl substances (PFAS), which the RMP only began monitoring in 2009 and for which no human consumption advisory levels have been established in California. These chemicals, used in stainproofing, waterproofing, and many other applications, are a new cause for concern. The 2019 survey was the...
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17
Jun

Thinking Like Beaver to Aid Yellow Creek

Last fall, the Maidu Summit Consortium, a nonprofit composed of nine Mountain Maidu tribal member groups, installed 73 BDAs—beaver dam analogs—in Yellow Creek, a tributary to the North Fork Feather River and a state-listed heritage trout stream. Swift Water Design and U.S. Fish and Wildlife Service designed the structures, and Mountain Maidu tribal youth worked with Swift Water to build them. The idea behind the structures, which mimic beaver dams, is to slow erosion, catch sediment, and build up the river bottom to reverse the incised channel—without importing soil and other materials or emitting carbon from heavy, diesel-powered equipment. “Before this project, PG&E had done some pond and plug projects to restore the meadow,” says Trina Cunningham, executive director of...
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17
Jun

Perspective:

As drought parches California, obliterates its snowpack, and reduces rivers to trickles, a familiar feud over water has resurfaced. Farmers want more of it to irrigate their crops, while fishermen and environmentalists want more left in rivers to protect the state’s Chinook salmon. Mainstream news outlets often portray the struggle as one between two groups ravaged by environmental whims and climate change. However, this interpretation weaves a false equivalence through the narrative. Whereas the state’s Chinook and coho salmon runs have withered to about a tenth of their historic magnitude, California’s agriculture industry has seen steady and soaring growth since its inception 150 years ago. Today, California’s farms occupy millions of acres, use 80 percent of our stored water supply,...
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17
Jun

Moonrise over Giant Marsh: New Monitoring Data from Two-Year-Old Supershore Project

Kathy Boyer is used to getting up in the dark so she can slide across the mudflats into the Bay at first light. But this past May, she got a once-in-a-decade treat. As the professor from SF State’s Estuary & Ocean Science Center aimed her boogie board at some two-year-old eelgrass beds growing off the Richmond shoreline, the Super Flower Blood Moon rose in the blue field of the western sky. “It’s hard to get up at 4 a.m. but if I wasn’t doing this work, I would have missed the eclipse,” said Devon Wallace, a student of Boyer’s and a recent SF State graduate, who was enjoying the chance to get in some field experience after a year grounded...
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17
Jun

Cooking Food in a Sacramento Shipping Channel?

The learned doctors attending the bedside of the Sacramento-San Joaquin River Delta agree on one thing: the patient is not doing well. What ails it, many students of the case suggest, is dehydration: the perennial artificial drought induced by withdrawals of water for human use. Recently, though, attention has turned to a comorbidity: malnutrition. Delta waters simply don’t generate enough basic food, in the form of phytoplankton, to sustain the food chains extending to salmon, sturgeon, and smelt.
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07
Jun

New research indicates that survival of juvenile Chinook salmon in the Sacramento River system can be significantly boosted by achieving key thresholds for river flow.

The findings, published in the journal Ecosphere, add important context to the general scientific understanding that more water in the river improves fish survival. Previous studies, the authors explain in their paper, have demonstrated that more juvenile salmon migrating toward the sea complete their journey when the Sacramento River system contains more water. Just how much water has been the source of much controversy among user groups. “These studies have not explored the potential nonlinearities between flow and survival, giving resource managers the difficult task of designing flows intended to help salmon without clear guidance on flow targets,” write the authors, led by Cyril Michel of the Institute of Marine Sciences at UC Santa Cruz. Studying migrating Chinook salmon smolts under a...
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07
Jun

Electrofishing is a powerful but underutilized tool for monitoring Delta fish, particularly species favoring “structured” habitats that are difficult to sample using more common methods like trawls and seines.

By analyzing fish catch data from past surveys, researchers Ryan McKenzie, of the US Fish and Wildlife Service, and Brian Mahardja, of the US Bureau of Reclamation, determined that electrofishing resulted in better detection rates for many native and non-native species than net-based surveys. Although electrofishing is currently restricted to freshwater areas of the Estuary and is more selective of larger fish and those with swim bladders, McKenzie and Mahardja recommend that resource managers employ the technique more widely to support long-term conservation planning. Electrofishing, or e-fishing as it’s sometimes known, uses a generator aboard a small boat to pass electricity through the water beneath and in front of the boat. “When the electricity moves through the water, it can...
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07
Jun

The robust monitoring programs established to track now-rare Delta smelt could benefit other native fishes, too.

Decades ago, resource managers first learned of declining Delta smelt numbers not through surveys targeting the once-abundant native fish, but rather as a byproduct of long-term monitoring programs for non-native striped bass. Now, the authors of a new study published in the March 2021 issue of San Francisco Estuary and Watershed Science advocate for the use of bycatch data from the recently established Enhanced Delta Smelt Monitoring (EDSM) program to better understand juvenile Chinook salmon distribution. “The scope of [this multi-million dollar Delta smelt survey] has not really been seen before in the Estuary,” says lead author Brian Mahardja, a biologist with the US Bureau of Reclamation, “that’s why there was a call to see what else we can gain...
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07
Jun

New insights into Delta smelt swimming behavior could help locate the increasingly elusive fish and prevent losses at the pumps.

Scientists know that smelt use tidal ebbs and flows to migrate landward to spawn, but the degree to which external cues influence behavior remains unclear. In a new study published in the March 2021 issue of San Francisco Estuary and Watershed Science, researchers used computer modeling to predict smelt distribution based on hypothesized swimming behaviors. Six increasingly complex behaviors were tested. For example, the “passive” category assumes that smelt do not swim at all, simply drifting with currents and tides. At the other end of the spectrum, the smelt respond to both turbidity and salinity cues. After assigning a behavior to simulated smelt distributed across the Delta, researchers ran a 133-day simulation of water year 2002, then compared the modeled...
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07
Jun

Water turbidity in the Sacramento-San Joaquin Delta can be used as a reliable indicator of smelt entrainment rates in the fish screens of the export pumps at the southern edge of the Estuary.

In a new study published in the March 2021 issue of San Francisco Estuary and Watershed Science, researchers Lenny Grimaldo, William Smith, and Matthew Nobriga used advanced statistical approaches to understand what factors best predict Delta smelt entrainment at the pumps. The paper builds upon research that Grimaldo conducted in the 2000s, which provided the basis for regulations established in the 2008 Delta smelt Biological Opinion. “This study reinforces previous work that adult Delta smelt salvage is largely explained by hydrodynamics, water clarity (turbidity), precipitation, and sub-adult abundance,” the authors write. Historically, when large numbers of smelt began to appear in the salvage screens of the Delta pumps, pumping would be curtailed. Today, Grimaldo says, the fish are so rare...
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moss ball oregon USFWS
21
May

Invasions

Almost two months after invasive zebra mussels were discovered in imported “moss balls” (actually algae) in a Seattle PetCo store, federal and state agencies are still trying to track the Trojan moss balls and keep the mussels out of vulnerable water bodies, including California’s. So far, contaminated moss balls have been found in 46 states (Virginia, Delaware, Rhode Island, and Hawaii are the exceptions) and most of Canada’s provinces. The US Fish & Wildlife Service has issued detailed guidance for getting rid of the moss balls, summarized as “Destroy, Dispose, Drain,” and the Pet Industry Joint Advisory Council has followed suit.  The Animal and Plant Health Inspection Service (APHIS), Customs and Border Protection, and the US Geological Survey are also...
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northern harrier-hull lab-UC Davis
11
May

Migrations

Northern harriers, long-winged rodent-hunting hawks, make impressive migrant journeys. Research by UC Davis’ Hull Lab sheds new light on these journeys. Harriers are a familiar sight in California’s wetlands, especially in winter. Researchers captured fifteen female harriers–ten in winter, five in spring–in Suisun Marsh and equipped with 14-gram GPS backpack transmitters, too heavy for use with the smaller males. Telemetry data from seven of the ten winter females revealed migrations of up to 600 miles, to nesting sites from the San Joaquin Valley to Washington State and Idaho.  The eighth, nicknamed Blanca for her pale yellow eyes, flew through British Columbia and Alaska all the way to the Arctic tundra, a 7,000-mile round trip that set a distance record for...
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Photo of bird watchers by Rick Lewis
08
May

Three Great Migration Stories -Tracking the Birds

Like water rains down and flows, spreads and seeps through an Estuary, touching the land along its path, so too do birds migrate across our planet.  ESTUARY loves a good bird story, and our reporter Joe Eaton writes most of them with great care for both birds and words, while photographer Rick Lewis always has his lens aimed at the feathers flying overhead or dipping in the water (see above). Read three great migration stories ….
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23
Mar

Flow Rules Stalled As Tunnel Advances

As California stares down the barrel of yet another dry year, alarm bells are already ringing over conditions in the Delta. Environmental groups, fishermen, tribes, and a host of others are calling on the State Water Resources Control Board to complete and implement a long-delayed update to the Water Quality Control Plan for the Bay and Delta (Bay-Delta Plan), to protect the imperiled ecosystem. At the same time, plans for a structure with the potential to divert more water than ever to southern cities and farms are creeping ahead. By law the Bay-Delta Plan — which establishes minimum flows through the Delta from the Sacramento and San Joaquin Rivers and their tributaries — is supposed to be reviewed every three...
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23
Mar

Beavers Make Good Neighbors

Much like when tech money reshapes an historical neighborhood, a beaver’s move downtown can cause the locals to worry. In Napa, the animals’ sprawling waterfront complexes create worrying pools along the riverbank, while the native cottonwoods are whittled down and threaten landowners’ roofs. It seems destined that two species known for their environmental engineering would struggle to live in unison. However, municipalities like Napa and Martinez in Contra Costa County have learned to live with their beavers, and the upcoming California Beaver Summit aims to set the record straight. “Our approach is hands-off,” says Jeremy Sarrow, a resource specialist with Napa County Flood Control and Water Conservation District, describing the county’s tack toward managing beaver dams built along inhabited waterfronts....
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01
Mar

North America’s largest and most ancient freshwater fish species, white sturgeon, hang out in some kinds of Estuary waterways more than others, scientists find.

 Researchers with the U.S. Geological Survey found that adult and sub-adult white sturgeon occupy deep open-water channels and shallow open-water shoals in equal measure, but don’t use shallow wetland channels. As a group, white sturgeon are characterized as amphidromous, meaning they regularly migrate between freshwater and the sea, in both directions, but not for the purpose of breeding. According to the study, which appears in the December 2020 issue of San Francisco Estuary and Watershed Science, adults in the local population use coastal habitats to some degree, but typically remain in the Estuary and lower Sacramento and San Joaquin rivers. There they congregate in deep areas with fine-sediment substrate, and are thought to move into shallow subtidal habitats to feed...
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01
Mar

As agencies wrangle over how best to protect the Delta’s dwindling native fish species, researchers want to see more consideration to the needs of the estuary’s birds.

 “If we want to restore the ecology of the Delta, we can’t just be looking in the water,” says Kristen E. Dybala of Point Blue Conservation Science. In a paper published in San Francisco Estuary and Watershed Science, Dybala and two co-authors make the case that “birds and their habitat needs are often not addressed in science syntheses, conservation planning, and large-scale restoration initiatives in the Delta.” While some birds use the same sloughs and channels that support such high-profile fishes as Chinook salmon and Delta smelt, other bird species rely on habitat types that fringe the Delta’s waterways. Indeed, while general habitat restoration in the Delta can provide multiple benefits for humans, fish and many birds, the authors observe...
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01
Mar

Filling significant recently identified gaps in monitoring spring-run Chinook is critical to protecting these threatened Central Valley salmon.

“There’s no way we can manage them for recovery if we don’t understand the biological processes that govern their dynamics through time and space,” says UC Santa Cruz/NOAA salmon expert Flora Cordoleani, lead author of a study reported in the December 2020 issue of San Francisco Estuary and Watershed Science. Cordoleani and colleagues identified the monitoring gaps while building a model of the spring-run Chinook life cycle. The model accounts for three self-sustaining populations of these at-risk fish, assessing survival of key life stages (eggs, fry, smolts and adults) as well as in key habitats (natal creeks, the Sacramento River, floodplains in the Sutter and Yolo bypasses, the Sacramento-San Joaquin Delta, and San Francisco Bay). “It’s a complex model, and...
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01
Mar

Human activity could undermine the success of efforts to reintroduce sea otters to San Francisco Bay.

 Although past studies have found that the Bay could support 1.5 times the entire current southern sea otter population, a new study from the Estuary & Ocean Science Center at San Francisco State University and published by PeerJ last November indicates that anthropogenic risks like contaminants, vessel traffic, and oil spills may constrain the otter’s ability to gain a foothold. The study, led by Jane Rudebusch, at the time graduate student at SFSU, looked at the types of human stressors present and ranked them according to factors like temporal overlap (frequency of its interaction with otters), intensity (consequence of that interaction), and management effectiveness (how well the stressor is mitigated by human regulation). The study concluded that high-speed vessel traffic,...
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01
Mar

The increasing flow of microplastics entering San Francisco Bay from trash, fleece clothing, car tires, and myriad other sources is likely being trapped by a surprising filter: native eelgrass (Zostera marina).

Miniscule polymer pieces the size of a sesame seed or tinier, microplastics pose a growing pollution threat to marine environments worldwide. To understand how microplastics accumulate in nearshore, urbanized environments, researchers quantified the prevalence of microplastics in and around the Zostera marina meadows of Deerness Sound, in the Orkney Islands of Scotland. Mark Hartl and colleagues at Heriot-Watt University found that microplastic flakes, fibers, and fragments were twice as concentrated in the water above eelgrass meadows as in adjacent control areas of sandy sediments. Sediments within the meadows contained 40% more microplastics than in the sandy areas. The scientists also found plastics attached to every one of the 60 blades of eelgrass they examined; in fact, microplastics were 20% more...
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