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fish

More than half the water diverted from Central Valley rivers is used to irrigate cattle-feed crops, implicating beef and dairy as top drivers of recent fish declines.

Recent findings, published in Nature Sustainability in March, strengthen the environmental arguments for going vegan while rewriting the familiar narrative that almonds and other high-value tree crops are the top hogs of Central Valley water resources. The study’s authors, led by Brian Richter of Virginia-based Sustainable Waters, focused on the arid West and found that irrigated crops like alfalfa and hay, more than any others, are drying out rivers. The reduced flows are pushing dozens of fish species toward extinction....
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Kinky Fish Spines Linked to Selenium

By Joe Eaton Scientists with the U.S. Geological Survey and the National Oceanic and Atmospheric Administration are using new tools to track selenium, with the Sacramento splittail, a California-endemic fish, as an indicator species. Robin Stewart, lead author of a new paper on splittail and selenium, is one of the region’s most seasoned current experts on bioaccumulation of metals in estuarine species. In some sampled splittail, selenium levels exceeded the proposed EPA protective criteria for fish ovaries. Liver levels, not...
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A career spent monitoring imperiled fish has given Randy Baxter a strong sense of the vulnerability of aquatic ecosystems.

“We’ve overtaxed the system,” he says. Baxter officially retired from the California Department of Fish and Wildlife last August, but still works two or three days a week as a “reemployed annuitant”—a big change from supervising a staff of 14 studying the threatened longfin smelt and other native fish. The reduced schedule gives him more time to fish, in California and on British Columbia’s Skeena River, and tend his orchids and carnivorous plants. Chicago-born Baxter grew up in Pacifica with...
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Bob Fujimura spent his entire career with the California Department of Fish and Wildlife.

Bob Fujimura spent his entire career with the California Department of Fish and Wildlife. From 1987 until his retirement in late 2018, Fujimura served in a variety of roles at the department—but he is likely best known for heading up its long-term monitoring of native fishes in the Bay and Delta. Beginning in the mid-2000s, he oversaw annual smelt surveys with far-reaching implications for management and conservation, including the Spring Kodiak Trawl, which determines the relative abundance and distribution of...
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Manmade features in the Delta, including riprap-armored banks, water diversion pipes, pilings, and woody debris, may be sending juvenile native fishes into the jaws of finned invaders.

“We know from a decade of doing survival studies that migrating juvenile salmon are dropping out of the system pretty much everywhere in the Delta,” says UC Santa Cruz fisheries biologist Brendan Lehman. “Physical habitat features are potentially aggregating predators and prey in ways detrimental to salmon smolts and steelhead.” The scientists report in the December 2019 San Francisco Estuary and Watershed Science that artificial light and submerged aquatic vegetation pose the most severe and widespread risks to native fishes....
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A recent test found more than 250 chemicals in the Delta’s Cache Slough, but “Dr Doom” says figuring out what they all are, and their concentrations, is beside the point in our efforts to understand stressors on native fish resilience.

“Knowing the effect on the fish is more informative than knowing which chemicals may be causing it,” says UC Davis’ Richard Connon (whose colleagues gave him his sinister title), referring to taking an ecological rather than regulatory perspective on fish health, and also to the less obvious sublethal effects of contaminants on fish behavior and reproduction. Connon is the lead author of a wide-ranging journal article in the December 2019 issue of SFEWS on how to better focus contaminants research...
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New shoreline strategies piloted in Puget Sound could help young fish in urbanized estuaries elsewhere.

When Seattle rebuilt its seawall in 2017, they hoped to make the hardened shoreline a little less daunting for the young salmon that hug it closely on their journey to the ocean. Project managers took a three-pronged approach. First, they added texture and complexity into the new concrete seawall to encourage invertebrates, food for the young fish, to settle in nooks and crannies and on horizontal “shelves” built into the wall. Mussels, ecosystem engineers, have settled on the shelves and...
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Pied-billed grebes are providing valuable biocontrol services in the Estuary by consuming red swamp crayfish, an invasive crustacean known to disrupt ecosystems.

Although grebes are primarily fish-eaters (they swallow their own feathers to cushion the sharp bones), this species also consumes significant numbers of crayfish, sometimes detaching the pincers before swallowing the good part. Native to southern swamps and bayous, the red swamp crayfish has been introduced in the Sacramento Valley and San Francisco Delta. According to the US Geological Survey, the species is established at Coyote Hills Regional Park and elsewhere around the Bay. The crayfish preys on the larval stages of...
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For the first time ever, an annual fish-counting survey has turned up zero Delta smelt—a dire milestone in Bay Area aquatic biology.

This does not mean the fish is extinct—yet—but it does mean that the Sacramento-San Joaquin Delta ecosystem is in disarray. The species, which lives its entire life in the estuary, is a key ecological indicator—and it was prolific until just a couple of decades ago. According to the California Department of Fish and Wildlife’s Fall Midwater Trawl survey, which provides an annual index on abundance for several fish species in the Delta, the Delta smelt index generally averaged several hundred fish...
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A marriage of robotics and artificial intelligence promises to automate the detection of harmful algal blooms, which can trigger shellfish harvesting bans and fill wildlife rescue centers with sickened animals.

The Imaging FlowCytobot (IFCB) takes water samples around the clock and photographs phytoplankton cells floating within. “It’s got a huge amount of potential for figuring out what plankton is in the water column and monitoring for HABs,” says Alexis Fischer, a postdoctoral fellow at the University of California, Santa Cruz with Raphael Kudela. Fischer and colleagues are building a phytoplankton image classifier already capable of identifying more than 90 percent of cells photographed by IFCB at the Santa Cruz Wharf. The...
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Incidental findings of a long-term study of brown bear predation on salmon have revealed a hidden link between the fish and forest health.

For 20 years, Tom Quinn, a professor in Aquatic and Fishery Sciences at the University of Washington, waded in southwestern Alaska’s Hansen Creek with his students, counting and measuring sockeye salmon carcasses in the stream. Quinn asked his students to toss the bodies on the north bank of the creek to avoid double counting; over the years, they tossed close to 295 tons of salmon onto the north bank. In 2016, Quinn and his colleagues and students took core samples...
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Dioxins Are Sticking Around Nearshore and in Fish, RMP Reports

As the “Fish-SMART” signs on local piers warn, the tissues of fish reeled in from San Francisco Bay waters can contain mercury or PCBs, but a new RMP report reminds us of a third contaminant of concern to human health: dioxins. The report, due out in October 2018 and prepared by staff of the San Francisco Estuary Institute and the SF Bay Regional Water Quality Control Board, confirms that while levels of this toxic contaminant in sediments nearshore have declined...
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Nighttime lights on bridges shining into bays and rivers can attract and confuse fish as they migrate at night, leaving them vulnerable to predation.

“Well-lighted bridges and dams can create twilight conditions that predators love, especially other fish,” says Peter Moyle, professor emeritus at UC Davis. He recounts that at one point the Red Bluff Diversion Dam was lit up at night and pikeminnow took the opportunity to prey on juvenile salmon. “Opening up the gates helped because the pikeminnow were headed upstream to spawn so didn’t really want to be there, and the juvenile salmon could move past the dam quickly at night.”...
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A wide-ranging Habitat Conservation Plan that could eventually protect up to 4800 acres of endangered species habitat in the Bay Area is the linchpin of a November agreement between the U.S. Fish and Wildlife Service and Pacific Gas and Electric Company.

Under the agreement, FWS issued the utility a 30-year incidental take permit for operations and maintenance activities in the nine Bay Area counties. The HCP includes strategies to avoid, minimize, and offset potential direct, indirect, and cumulative effects of PG&E’s O&M and minor new construction activities on 32 threatened or endangered species. The parties are hailing the landscape-scale plan as an improvement over the project-by-project process they previously operated under, as it will enable PG&E to complete projects more quickly...
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In hot water due to climate change, many ocean fish are moving to higher latitudes or deeper waters to find the conditions they need to survive.

These include lobster, black bass, and Atlantic cod, all of which have supported iconic fisheries along the Eastern seaboard of the United States. “Ocean animals are moving ten times faster than animals fleeing climate change on land,” says Rutgers University marine biologist Malin Pinsky, whose Rutgers OceanAdapt website enables visitors to explore changes in marine species distributions over recent decades. These range shifts are causing headaches for fishing fleets, which are forced to head farther out to sea or hundreds of miles further from...
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Sport Fish Still Not Squeaky Clean

Toxic flame retardants quickly declined in Bay-caught fish, once banned, but legacy mercury persists, according to the most recent year of sampling. As the region’s collaborative monitoring program for Bay contaminants — the RMP — arrives at its 25th birthday, its long-term commitment to consistent data collection for the purposes of targeted environmental management is showing its mettle. The RMP has been catching and testing a wide array of species of popular sport fish, ranging from giant sturgeon to tiny...
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No Scapefish in Drought Wars

According to the Biblical book of Leviticus, the ancient Israelites designated a goat to bear the weight of their sins. Nowadays, the scapegoat is not required to be a goat. When it comes to assessing blame for the worsening California drought, a scapefish will suffice. Some media outlets, notably the Wall Street Journal in a recent op-ed piece, point to the hapless Delta smelt as a culprit in the state’s water crisis, as well as a prime example of the...
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Small Fish Test Helps Target PCB Clean Up

Jay Davis didn’t expect much from a pilot test for PCBs in silversides and topsmelt that live on the edges of the San Francisco Bay. The monitoring program he heads only ran the test on these small fish, which rarely grow more than 3-4 inches long, because it was simple to piggyback on an existing study of mercury in the same fish samples. “I thought it wouldn’t really be a big deal,” says Davis, who is lead scientist for the...
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Freeing Fish While Locking Up Mercury

The restoration of the South Bay salt ponds to tidal wetland has, from the very beginning, been an exercise in adaptive management: take an action; monitor the results; make any indicated fixes; repeat. There’s no better example than Pond A8, where the Guadalupe River enters San Francisco Bay via Alviso Slough. Restoration planners were worried that connecting the former salt evaporation pond with the Bay could introduce long-dormant mercury to the wider ecosystem, and initial studies of levels in water...
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The San Francisco Bay-Delta is named in the federal Clean Water Act as one of 28 “estuaries of national significance." For over 20 years, the San Francisco Estuary Partnership has worked together with local communities and federal and state agencies to improve the health of California’s most urbanized estuary.

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