Tallying Bird Populations Then and Now

Native Species



15
Dec

Tallying Bird Populations Then and Now

How many ducks and geese used the Estuary before the Gold Rush? The numbers are beyond conjecture, but they must have been mind-boggling. Observers writing about a hundred years ago noted major decreases during the era of market hunting, when waterfowl were shot to supply the restaurants and stores of California’s emerging cities, but offered no hard numbers. However, they recorded their observations of the abundance and seasonal presence of different species. Since then, government surveys, Audubon Society Christmas Bird Counts, and sport hunting records show a mix of change and continuity, with some duck species either scarce or common in the last century and now, and other common species becoming rare or vice versa. The US Fish and Wildlife...
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18
Nov

As organizations and agencies scramble to preserve the Central Valley’s dwindling Chinook salmon runs, a group of scientists believes they may be overlooking a key factor in the decades-long decline of the fish: disease.

In a paper published in September’s issue of San Francisco Estuary and Watershed Science, a research team proposes that diseases—caused by viruses, bacteria and other microbes—could be suppressing juvenile salmon survival in a river system that once hosted millions of adult spawners each year. According to tracking studies, nearly all juvenile Chinook born from natural spawning die before they reach the Golden Gate Bridge; habitat enhancement efforts have failed to mitigate this mortality rate. Short-term studies of Central Valley salmon have indicated high rates of infectious diseases, which lead author Brendan Lehman of UC Santa Cruz says demonstrates the need for ongoing systemwide monitoring. This could involve sampling fish directly for infections or conducting DNA testing of water samples. A...
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18
Nov

Current estimates of young salmon lost to the south Delta pumps are based on a smattering of studies from the 1970s and should be updated, according to a new analysis.

“They don’t represent current operations,” says Ukiah-based consultant Andrew Jahn, lead author of the analysis reported in the September 2020 issue of San Francisco Estuary and Watershed Science. Current operations at the State Water Project (SWP) and the Central Valley Project (CVP) can reverse flows in the Old and Middle rivers, diverting salmon on their way to the ocean towards the projects. Existing salmon loss estimates also fail to account for a likely Old River hotspot for predators, drawn to the influx of salmon and other fish near the two water projects. Evidence of this hotspot lies in the numerous acoustic tags from young salmon to be found in the sediment, which were presumably defecated by striped bass, as well as...
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18
Nov

Fish passage structures can be improved for the benefit of multiple species, if they are designed to account for differences in behavior, physical ability and size, according to a new literature review.

Historically, most fish passages have been designed to help native salmon return to their upstream habitat and spawning grounds, with little consideration for other migrating species such as sturgeon and lampreys. “There is an assumption that if you just build a fish passage structure, fish will go thorough it, but that is not always the case,” says Department of Water Resources fisheries biologist Zoltan Matica, who conducted the review. “The challenge is to understand that this isn’t only a physical barrier, it can be also a mental barrier.” For example, some species that engage in schooling behavior, such as shad, may refuse to even enter a structure if it limits them to passing one at a time. According to the...
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18
Nov

Spawning and rearing habitat for important forage-fish species in San Francisco Bay apparently shifts geographically by many miles depending on how much freshwater is flowing into the Estuary.

In a recent study, a team of scientists found that in a dry year, Pacific herring and longfin smelt larvae occurred farther up the Estuary than in a wet year, when spawning and recruitment was pushed seaward. The results suggest that the fish have broader geographic ranges than previously believed, a finding that could inform efforts to manage and protect their habitat. Biologists have long assumed that longfin smelt, a protected species in steep decline for decades, spawn strictly in upper reaches of the Estuary. But by towing a weighted hoop net behind a research vessel during the dry year of 2016 and again in the following year of heavy rainfall, the authors of the new study, published in October’s...
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28
Sep

Science in Short ~ Fish Podcast

David Ayers: How Fish Interact with Wetlands Topography  In this podcast, Estuary News reporter Alastair Bland and UC Davis PhD student and fish researcher David Ayers discuss the Sacramento-San Joaquin Delta, its fish, its marshlands, its flows, and its future. Ayers explains the focus of his research, which seeks to reveal how underwater topography in the wetlands fringing the estuary affects interactions between predators and small fish. While restoration projects often focus on adding more water to this ecosystem and encouraging that water to overflow the river’s banks, Ayers says small fish need more than just water and wetlands to survive. Variation in habitat features, such as the width and depth of wetland channels that wind through these ecosystems, create a...
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22
Sep

Heavy Lifting for Fish

Ted Frink recalls watching Jacques Cousteau’s television specials when he was growing up in coastal Orange County. “I envisioned myself as Cousteau,” says Frink, a fisheries biologist with the California Department of Water Resources (DWR) now approaching retirement. “My folks encouraged my interest in science. I knew I could be a biologist.” That early inspiration sparked a long and varied career, culminating in his work as chief of DWR’s Special Restoration Initiatives Branch and his role in mitigating obstacles to salmon and steelhead passage in streams all over the state. Frink focused on salmonids and other anadromous fish early on, graduating from Humboldt State in 1984 with a degree in fisheries ecology and a minor in hydrology. His first professional...
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22
Sep

Trolling for Salmon by Kayak

Whales scare us much more than sharks. They erupt from the ocean with a rush of displaced water and a poof of air. A collision could be disastrous. “Whale – go-go-go!” I shout. We pedal double-time to dodge the humpback, behind us and approaching from the left. A moment later it surfaces again, with another poof, now off to our right, moving away. We relax and slow back to our standard trolling speed of about 2.5 miles per hour, and we plod forward. My brother Andrew and I are in a pedal-powered kayak two miles from shore off the Marin County coast, where anchovies so thick they darken the water have attracted birds, porpoises, sea lions, thresher sharks, humpback whales...
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22
Sep

Retrofitted Houseboat IDs Fish in the Shallows

On a hazy Delta morning at Isleton’s B & W Resort, more than a dozen trucks are already neatly arrayed in the double-long parking spaces with empty trailers facing the boat launch: evidence of fishers and boaters getting an early start on their Labor Day weekend. Randy Mager, sporting a flannel shirt and worn baseball cap, radiates earnest enthusiasm, which for a 20-year state government veteran is as refreshing and rare as a Delta smelt. “I am more excited about this than I have been about pretty much anything else in my career,” says Mager, a senior environmental scientist with California’s Department of Water Resources (DWR). Randy Mager. Photo: Isaac Pearlman The subject of his palpable excitement lays in the...
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13
Sep

By looking solely at the results of a single annual fish-counting survey, Californians may be seeing an incomplete reflection of Bay-Delta fish population trends.

A team of scientists analyzed 14 survey programs carried out by state and federal agencies, as well as UC Davis, and concluded that employing such a diverse variety of long-term surveys is essential for accurately tracking and assessing the overall health of San Francisco Estuary’s ecosystem and its resident fishes. The research is described in the June issue of San Francisco Estuary and Watershed Science. Lead author Dylan Stompe, of UC Davis, explains that the research arose from concerns that too many people – reporters included – have relied on the results of one annual survey, the California Department of Fish and Wildlife’s Fall Midwater Trawl, to make sweeping conclusions about the health and abundance of several fish species. The...
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13
Sep

A unique adaptive behavioral trait that may once have helped winter-run Chinook salmon thrive in the Sacramento River system could now be working against the fish as they face extinction.

The trait – which cues fish when to spawn based on water temperature – isn’t syncing up with current conditions in the Sacramento River below Shasta Dam. A paper published in the June issue of San Francisco Estuary and Watershed Science, reports that cooler springtime river temperatures seem to prompt earlier winter-run spawning while warmer temperatures push back the peak spawning period by a week or two. Under historic conditions, when winter-run Chinook spawned in high-elevation streams now inaccessible to the fish, their behavioral adaptability would have helped the temperature-sensitive eggs and offspring in two ways—by ensuring “sufficient time for egg maturation in cool years, while secondarily preventing egg and alevin mortality in warm years,” write authors Eva Dusek Jennings,...
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05
Aug

Great whales, the largest creatures in the sea, can help mitigate climate change by locking up carbon in their massive bodies and boosting phytoplankton with their waste products.

A preliminary study by researchers with the International Monetary Fund’s Institute for Capacity Development, the University of Notre Dame, and Duke University found that each great whale sequesters an average of 33 tons of CO2 over its lifetime, taking that carbon out of the atmosphere for centuries: when a whale dies and sinks to the sea floor, it takes that carbon with it, says Joe Roman, conservation biologist and author of Whale. (Compare that to a tree, which sequesters about 48 pounds of CO2 per year.) Whales act as nutrient pumps in the ocean as they dive and feed and then surface, nourishing phytoplankton growth with their waste products, which contain the iron and nitrogen the marine algae need to...
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05
Aug

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. “We estimate that 60 fish species in the western US are at elevated risk of imperilment or extinction due to flow depletion, and that 53 (88%) of these are primarily due to irrigation of cattle-feed crops,” the scientists wrote in...
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06
Jul

Sacramento pikeminnow and introduced striped bass in the middle Sacramento River eat a surprisingly similar diet, says a new study in San Francisco Estuary and Watershed Science.

Both species have been implicated in the decline of vulnerable native species in the river, particularly juvenile Chinook salmon, says lead author Dylan Stompe, a PhD student and researcher at the University of California at Davis. For eight months in 2017, Stompe and fellow researchers with the California State University at Chico and the California Department of Fish and Wildlife surveyed a 35 kilometer reach of the river outside Chico for the two predatory fish. They baited hooks with with sardines, worms, and chicken liver and fished from an anchored boat. When they brought a pikeminnow or striped bass on board, the researchers performed a gastric lavage, in which pulses of pressurized water are directed into the fish’s esophagus, causing...
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06
Jul

Should the striped bass be a suspect in the decline of the Delta smelt?

Writing in the March issue of San Francisco Estuary and Watershed Science, US Fish and Wildlife Service biologists Matt Nobriga and Will Smith suggest that the smelt’s baseline might have shifted long before anyone was paying attention, and striped bass predation may have constrained its numbers before recent water diversions and food web changes added their effects. The smelt’s historic abundance is unknown; systematic surveys didn’t begin until 1959. But it’s thought to have evolved its boom-and-bust life history in response to predation pressure from native fish or birds. Was the bass, introduced in the late 19th century, one predator too many, or too effective? Nobriga notes that Delta smelt don’t respond predictably to changing flows: “From what we know...
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18
Jun

Planting for Resilience

Travel brochures for Napa County almost universally feature the same images: a valley floor carpeted with vineyards, nestled between hillsides dotted with spreading valley oaks. As climate change brings hotter days — and more of them — to the county, these twin pillars of the landscape, grapevines and oak trees, are both challenged by it and central to local resilience strategies.
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16
Apr

Beaver dams may offer wildfire protection to western watersheds, in addition to providing better-known benefits such as groundwater recharge, wetland and habitat creation, and riparian restoration.

A new study by California State University Channel Islands professor Emily Fairfax analyzed satellite-derived vegetation indices of riparian areas and beaver dams mapped via Google Earth. At the same time, Fairfax analyzed data for large (over 30,000 acre) wildfires that had occurred between 2000 and 2018 in California, Wyoming, Colorado, Idaho, and Oregon, and compared the fate of beaver-dammed areas to areas without dams. Fairfax found that riparian corridors within 100 meters of beaver ponds were buffered from wildfires. “In all of them, the beaver ponds made it through the fire and stayed much greener. The beaver-dammed riparian zones were functioning differently,” says Fairfax. While the riparian areas without beaver dams eventually recovered on their own, she says, vegetation in...
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16
Apr

A new project should dramatically improve conditions for endangered steelhead trout in the lower reaches of Alameda Creek.

The project is part of a long-term effort to restore steelhead to Alameda Creek. Last year, for the first time in decades, the San Francisco Public Utilities Commission began releasing water from a newly retrofitted dam, effectively reviving an important tributary stream. Also in 2019, the Alameda County Flood Control District began construction of a key fish ladder at the BART line crossing that will allow adult steelhead to access the river’s headwaters. The new fish passage enhancement plan focuses on a section of the stream that flows through a highly urbanized area. Largely contained within channels of concrete and riprap, the water courses under a freeway overpass and several boulevard bridges. The water is warm, swift and shallow—an unfriendly...
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16
Apr

A resurgence of dinoflagellates, which can cause harmful algal blooms, may be in the cards for some bays along the U.S. West Coast.

A resurgence of dinoflagellates, which can cause harmful algal blooms, may be in the cards for some bays along the U.S. West Coast. Scientists at UC Santa Cruz have been monitoring phytoplankton weekly at the town’s Municipal Wharf since 2002. In 2018, Alexis Fischer, then a postdoctoral fellow at UC Santa Cruz, augmented these observations with an Imaging FlowCytobot (IFCB) that photographed wharf phytoplankton hourly. She also developed a machine learning classification algorithm to automate identification of the organisms. In 2004-2007 and 2017-2018, the scientists noticed that diatoms, typically dominant, were getting upstaged by dinoflagellates. To get to the root of this role switch, Fischer examined local and regional environmental patterns. She now reports in Limnology and Oceanography that both...
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16
Apr

New archaeological evidence from the South Bay strengthens the case that Chinook salmon spawned naturally in the Guadalupe River.

Albion Environmental, a Santa Cruz research consulting firm, and researchers from Santa Clara University analyzed thousands of fish bones excavated from a 19th century indigenous village on Mission Creek, a historical Guadalupe River tributary long since buried under modern urban development. In an abstract of their research, which has not yet been published, the authors describe using DNA sequencing on 55 confirmed salmonid bones. They identified 52 as belonging to steelhead trout and three as Chinook salmon. Whether Chinook occurred naturally in the South Bay’s watersheds has been debated for years, and the new research seems to settle the matter. While the salmon could have been caught in the ocean or Bay and transported to the native village, the near...
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