While it’s been a tough year for marine mammals along the California coast, local San Francisco Bay conditions may have afforded scientists a unique opportunity to study emerging ocean problems.

Native Species



08
Aug

While it’s been a tough year for marine mammals along the California coast, local San Francisco Bay conditions may have afforded scientists a unique opportunity to study emerging ocean problems.

The Marine Mammal Center participated in 12 necropsies of deceased gray whales in and around the Bay. Later in the year, malnourished Guadalupe fur seals stranded along the coast at a historically high rate. In June, a surprisingly early toxic algae bloom off the coast of San Luis Obispo caused a rash of cases of Domoic Acid Toxicity among pregnant and yearling California sea lions. Dr. Cara Field, staff veterinarian at The Marine Mammal Center, has some theories as to why these events have occurred. Whale necropsies showed significant emaciation, consistent with studies done on gray whales in Mexico this past winter showing that many were already in poor body condition after returning from their summer feeding grounds in the...
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17
Jun

Tailing a Thrush

By Joe Eaton Researchers like Point Blue Conservation Science ecologist Tom Gardali have equipped Swainson’s thrushes, weighing just over an ounce, with tiny, one-gram GPS tags. If recovered, the tag shows the thrush’s exact winter destination, information vital to border-crossing conservation efforts. “You only get a few readings,” says Gardali, “and you still need to get the tag back. But GPS goes to a spot on the map. This is Holy Grail stuff.”  Sierra/Cascade thrushes were presumed to migrate to Mexico like their coastal cousins. When researchers included thrushes from Mount Lassen and Lake Tahoe in their GPS tracking, they learned otherwise. “The mountain birds are going from Mexico to Panama, possibly as far as Columbia.”
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17
Jun

Brinkmanship for Frail Smelt

Delta smelt had a bad year in 2017. Although scientists are still analyzing the data, the message seems to be that strong freshwater flows alone are not sufficient to allow the population to increase. The resulting sense of urgency has led fish biologists to consider how cultured smelt, raised in hatcheries, could be used to supplement the wild population.
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13
May

Sandra Scoggin has the qualities the San Francisco Bay Joint Venture needs in a leader at what she calls a ‘pivot point’ for the partnership.

In the early days, when the wetland protection and restoration landscape was less complex, the JV “could be everywhere and do everything.” Now it needs to be more strategic. “I’m a listener, a synthesizer, and I’m pretty good at herding diverse interests toward shared goals,” says Scoggin, who is taking over the 20-year-old wildlife habitat venture after 16 years in second seat. “The JV is built on deep and lasting relationships,” she says, both awe and pride in her voice. Scoggin grew up in Los Angeles. After early work studying songbird nesting, she developed a soft spot for the Swainson’s thrush: “It’s like a ghost of the riparian forest, with an ethereal, beautiful song that comes out of nowhere.” In...
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20
Mar

High Road or High Water for Wildlife

While we were cooped up inside waiting out February’s storms, many animals were on the move. Cameras positioned along a creek in the Pacheco Pass wildlife corridor captured footage of animals passing through a culvert under a bridge on SR-152 that crosses Pacheco Creek. “We caught a bobcat on camera walking through the creek,” says Tanya Diamond...
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20
Mar

SOS for Finicky Native

In 2016, restoration managers with The Nature Conservancy discovered that western sycamores planted along the Sacramento River had hybridized with the non-native London plane tree. The native sycamore is “kind of a messy tree,” says project manager Ryan Luster. “The branches break off and create cavities that wildlife love to use.” Concerns about the tree’s status first arose in the 1990s...
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13
Feb

Estuary’s Question of the Month: What is the weirdest species in the Estuary and why?

A fall flight over the Mexican coast where the Colorado River meets the Sea of Cortez offered me a gut-punching, eye-screwing, visual on the results of impaired flow. The semantics of ‘unimpaired’ and ‘impaired’ flow have laced the language of California water management debates since some engineer invented these politically ‘neutral’ terms long ago. The terms refer to our alteration of freshwater flows from snowmelt and runoff by dams and diversions. But whatever the labels, or whichever estuary you’re referring to, keeping these flows from reaching the sea via rivers can starve these aquatic ecosystems of their liquid life force. Whether it’s the vast yellowing salt flats that are all that remain of the mighty marshes of the pre-dam Colorado...
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13
Feb

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 native frogs (including the endangered California red-legged frog) and newts. Recent research led by Gary Bucciarelli at UCLA suggests that red swamp crayfish in Southern California streams interfere with the ability of aquatic dragonfly nymphs to control mosquito larvae, including...
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13
Feb

A gene tells Chinook salmon whether to return to their native streams to spawn in spring, fall, or sometime in-between, according to new research.

The finding, by UC Davis graduate student Tasha Thompson and colleagues, helps distinguish between spring- and fall-run fish—and could help save spring-run salmon from human-hastened extinction. Fall-run populations enter rivers in autumn and spawn immediately. By contrast, spring-run fish return during peak snowmelt, linger in tributaries through summer, and spawn around the same time as their fall-run brethren. “Spring-run fish are special for a lot of reasons,” Thompson says. Spring-run salmon historically spawned in the upper portion of watersheds, nourishing ecosystems with marine nutrients when they died. Today, these habitat preferences have left spring-run Chinook vulnerable thanks to dams, logging, climate change, and other human-caused alterations to their habitat. “People once thought spring-runs would easily evolve from fall because they’re...
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Delta Smelt
13
Feb

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 into the early 2000s. Then, in about 2003, numbers of Delta smelt, as well as several other native fishes, began to plunge. To Jonathan Rosenfield, the lead scientist with The Bay Institute, it’s clear what’s going on. “The one thing...
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13
Dec

Sleuthing Sturgeon Snags

Local green sturgeon are struggling. The population that spawns in the Sacramento –San Joaquin River Delta was declared federally threatened in 2006. Researchers at UC Davis, which hosts the world’s only green sturgeon rearing program, are now trying to figure out why the fish is in trouble. “If we knew how large they are when they’re moving through each portion of the system, we’d know a lot more about the threats they face at each life state, and where we need to put our energy,” says postdoctoral fellow Anna Steel.
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13
Dec

Hauling Out on Higher Ground

Harbor Seals “have this dual existence,” says Sarah Allen, National Park Service ecologist. “They’re tied to the land physiologically and tied to the bay waters for food and travel.” From rocky islets to tidal marshes, the Bay shoreline offers respite to these native marine mammals. Rocky islets like the Castro Rocks, located near the Richmond-San Rafael Bridge, are particularly important refuges -- but more than half the islets that exist throughout the Bay are likely to be erased by sea-level rise this century. Meanwhile, the ability of tidal marsh habitats to naturally respond to rising waters offers hope.
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13
Dec

Shark Hunt Stand Off

In the spring and summer months, anglers armed with heavy line and large hooks drop anchor in the murky, current-torn waters between Alcatraz and the Golden Gate Bridge seeking the elusive, and occasionally gigantic, broadnose sevengill shark. As social-media hype stokes excitement among trophy seekers, some other fisherfolk and conservationists want to see the pursuit ended before it depletes shark numbers. While interest in catching large, breeding-age sevelgills has risen in recent years, it remains unclear whether the population can sustain such fishing. “There hasn’t been any long-term monitoring study of the population, so we have no baseline estimate,” says Sean Van Sommeran, founder of the Pelagic Shark Research Foundation.
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13
Nov

The Nature Conservancy’s venture in growing food crops for wintering cranes on Staten Island is under fire from an unexpected source—the Wetlands Preservation Foundation.

The nonprofit, headed by Stockton tomato packer Dino Cortopassi, is suing TNC and the California Department of Water Resources, which holds a conservation easement on Staten Island, alleging farming practices that cause soil subsidence and threaten levee integrity, and misuse of revenue from farm operations. The 9200-acre farm, acquired by TNC in 2001, is a major destination for migratory greater and lesser sandhill cranes (the latter a California endangered species) as well as Aleutian cackling geese and other birds. As habitat is replaced by houses, orchards, and vineyards, a third of the state’s crane population converges on the island to feed in corn and triticale fields and roost at night. While corn cultivation is recognized as depleting the Delta’s peat...
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13
Nov

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 from the white spruce growing on both sides of the creek. The samples revealed that over the course of the study the salmon-fertilized trees on the north bank had caught up in growth with the taller trees on the south...
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13
Nov

Floods and droughts can cause pools and riffles—and the bugs that live in them—to become more homogenous.

For years, scientists monitoring water quality in streams and rivers have collected mixed samples of aquatic invertebrates from riffles, pools, and transition zones. But UC Santa Barbara stream ecologist David Herbst and his colleagues recently finished a 15-year study of the benthic life in small streams of the central Sierra that examined pools and riffles separately. They found that during flood and drought events, these habitats and their inhabitants become more uniform. But while floods come and go, droughts can have longer-term effects on the biodiversity in the stream. “As stream flows go down, the riffles go dry first,” says Herbst. “The riffle habitat, the richest place in the stream, can be depleted during drought conditions. The habitat itself is...
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26
Sep

Spring-run Salmon Need More Than Simple Answers

Salmon once flourished in California despite huge swings in climate that were far more extreme than those today. But then people re-engineered the state’s waterways to meet their own needs. “Complexity is what salmon thrive on, and we’ve been making their habitat simpler and simpler,” says biologist Bruce Herbold.  “We haven’t been playing to their strengths.”
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26
Sep

Following the Water: Bobcats in Coyote Valley

From a bird’s eye view, the area between the Santa Cruz and Diablo mountain ranges looks like any typical valley. But the work being done by Tanya Diamond, a wildlife biologist with Pathways for Wildlife, shows that the Coyote Valley offers much more to native wildlife and conservationists than mere open space.
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26
Sep

Big Restoration Experiment for the Delta’s Dutch Slough

Development agreements were already in place for three parcels of land around Dutch Slough when John Cain first took a hike in this West Delta area in the spring of 1999. “It was clear as day to me that removing the levee would be a great way to restore freshwater wetlands at the mouth of Marsh Creek,” says Cain. Almost two decades later, earthmoving equipment is now preparing 1,178 acres for conversion to marsh habitat.
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13
Aug

Help may be on the way for critically endangered southern resident killer whales.

NOAA Fisheries and the Washington Department of Fish and Wildlife have partnered to produce a list of the west coast Chinook salmon stocks most important to the whale’s survival. This list comes as a part of a special action plan by NOAA to address the three primary threats to the southern resident killer whales: Chemical contaminants, vessel traffic, and lack of prey. The salmon, themselves endangered, are the preferred food source for the whales, and identifying the salmon runs—which include Sacramento River and San Joaquin River runs—that most overlap with the range of the southern residents could be crucial to their eventual recovery. “Those fish support not only the commercial fishery but the whales that migrate north after they leave...
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