Heart

Subterms

    More stories

    • 113 Shares119 Views

      in Heart

      Tiger sharks helped discover the world’s largest seagrass prairie

      by

      Scientists have teamed up with tiger sharks to uncover the largest expanse of seagrasses on Earth.  

      A massive survey of the Bahamas Banks — a cluster of underwater plateaus surrounding the Bahama archipelago — reveals 92,000 square kilometers of seagrasses, marine biologist Oliver Shipley and colleagues report November 1 in Nature Communications. That area is roughly equivalent to half the size of Florida.

      The finding expands the estimated global area covered by seagrasses by 41 percent — a potential boon for Earth’s climate, says Shipley, of the Herndon, Va.–based ocean conservation nonprofit Beneath The Waves.

      Austin Gallagher, a marine biologist from ocean conservation nonprofit Beneath The Waves, surveys a seagrass field in the Bahamas Banks.Cristina Mittermeier and SeaLegacy

      Seagrasses can sequester carbon for millennia at rates 35 times faster than tropical rainforests. The newly mapped sea prairie may store 630 million metric tons of carbon, or about a quarter of the carbon trapped by seagrasses worldwide, the team estimates.

      Mapping that much seagrass was a colossal task, Shipley says. Guided by previous satellite observations, he and colleagues dove into the sparkling blue waters 2,542 times to survey the meadows up close. The team also recruited eight tiger sharks to aid their efforts. Similar to lions that stalk zebra through tall grasses on the African savanna, the sharks patrol fields of wavy seagrasses for grazing animals to eat (SN: 1/29/18; SN: 5/21/19, SN: 2/16/17).

      “We wouldn’t have been able to map anywhere near the extent that we mapped without the help of tiger sharks,” Shipley says.

      The team captured the sharks with drumlines and hauled each one onto a boat, mounting a camera and tracking device onto the animal’s back before releasing it. The sharks were typically back in the water in under 10 minutes. The team operated like “a NASCAR pit crew,” Shipley says.

      Researchers had previously suggested tracking seagrass-grazing sea turtles and manatees to locate pastures. But tiger sharks were a smart choice because they roam farther and deeper, says Marjolijn Christianen, a marine ecologist at Wageningen University & Research in the Netherlands who was not involved in the new work. “That’s an advantage.”

      [embedded content]
      Camera-equipped tiger sharks like this one helped uncover the world’s largest seagrass bed, penetrating areas too deep or remote for divers.

      Shipley and colleagues plan to collaborate with other animals — including ocean sunfish — to uncover more submarine meadows (SN: 5/1/15). “With this [approach], the world’s our oyster,” he says. More

    • 163 Shares159 Views

      in Heart

      Sharks face rising odds of extinction even as other big fish populations recover

      by

      After decades of population declines, the future is looking brighter for several tuna and billfish species, such as southern bluefin tuna, black marlins and swordfish, thanks to years of successful fisheries management and conservation actions. But some sharks that live in these fishes’ open water habitats are still in trouble, new research suggests.

      These sharks, including oceanic whitetips and porbeagles, are often caught by accident within tuna and billfish fisheries. And a lack of dedicated management of these species has meant their chances of extinction continue to rise, researchers report in the Nov. 11 Science. 

      The analysis evaluates the extinction risk of 18 species of large ocean fish over nearly seven decades. It provides “a view of the open ocean that we have not had before,” says Colin Simpfendorfer, a marine biologist at James Cook University in Australia who was not involved in this research.

      “Most of this information was available for individual species, but the synthesis for all of the species provides a much broader picture of what is happening in this important ecosystem,” he says.

      In recent years, major global biodiversity assessments have documented declines in species and ecosystems across the globe, says Maria José Juan-Jordá, a fisheries ecologist at the Spanish Institute of Oceanography in Madrid. But these patterns are poorly understood in the oceans.

      To fill this gap, Juan-Jordá and her colleagues looked to the International Union for Conservation of Nature’s Red List, which evaluates changes in a species’s extinction risk. The Red List Index evaluates the risk of extinction of an entire group of species. The team specifically targeted tunas, billfishes and sharks — large predatory fishes that have influential roles in their open ocean ecosystems. 

      Red List Index assessments occur every four to 10 years. In the new study, the researchers built on the Red List criteria to develop a way of tracking extinction risk continuously over time, rather than just within the IUCN intervals.

      Juan-Jordá and her colleagues did this by compiling data on species’ average age at reproductive maturity, changes in population biomass and abundance from fish stock assessments for seven tuna species, like the vulnerable bigeye and endangered southern bluefin; six billfish species, like black marlin and sailfish; and five shark species. The team combined the data to calculate extinction risk trends for these 18 species from 1950 to 2019.

      The team found that the extinction risk for tunas and billfishes increased throughout the last half of the 20th century, with the trend reversing for tunas starting in the 1990s and billfishes in the 2010s. These shifts are tied to known reductions in fishing deaths for these species that occurred at the same time.

      The results are positive for tunas and billfishes, Simpfendorfer says. But three of the seven tunas and three of the six billfishes that the researchers looked at are still considered near threatened, vulnerable or endangered. “Now is not the time for complacency in managing these species,” Simpfendorfer says.

      But shark species are floundering in these very same waters where tuna and billfish are fished, where the sharks are often caught as bycatch. 

      Many open ocean sharks — like the silky shark (Carcharhinus falciformis) (pictured) — continue to decline, often accidentally caught by fishers seeking other large fish.Fabio Forget

      “While we are increasingly sustainably managing the commercially important, valuable target species of tunas and billfishes,” says Juan-Jordá, “shark populations continue to decline, therefore, the risk of extinction has continued to increase.”

      Some solutions going forward, says Juan-Jordá, include catch limits for some species and establishing sustainability goals within tuna and billfish fisheries beyond just the targeted species, addressing the issue of sharks that are incidentally caught. And it’s important to see if measures taken to reduce shark bycatch deaths are actually effective, she says. 

      “There is a clear need for significant improvement in shark-focused management, and organizations responsible for their management need to act quickly before it is too late,” Simpfendorfer says.  More

    • 113 Shares119 Views

      in Heart

      Greenland’s frozen hinterlands are bleeding worse than we thought

      by

      Sea level rise may proceed faster than expected in the coming decades, as a gargantuan flow of ice slithering out of Greenland’s remote interior both picks up speed and shrinks.

      By the end of the century, the ice stream’s deterioration could contribute to nearly 16 millimeters of global sea level rise — more than six times the amount scientists had previously estimated, researchers report November 9 in Nature.

      The finding suggests that inland portions of large ice flows elsewhere could also be withering and accelerating due to human-caused climate change, and that past research has probably underestimated the rates at which the ice will contribute to sea level rise (SN: 3/10/22).

      “It’s not something that we expected,” says Shfaqat Abbas Khan, a glaciologist at the Technical University of Denmark in Kongens Lyngby. “Greenland and Antarctica’s contributions to sea level rise in the next 80 years will be significantly larger than we have predicted until now.”

      In the new study, Khan and colleagues focused on the Northeast Greenland Ice Stream, a titanic conveyor belt of solid ice that crawls about 600 kilometers out of the landmass’s hinterland and into the sea. It drains about 12 percent of the country’s entire ice sheet and contains enough water to raise global sea level more than a meter. Near the coast, the ice stream splits into two glaciers, Nioghalvfjerdsfjord and Zachariae Isstrøm.

      While frozen, these glaciers keep the ice behind them from rushing into the sea, much like dams hold back water in a river (SN: 6/17/21). When the ice shelf of Zachariae Isstrøm collapsed about a decade ago, scientists found that the flow of ice behind the glacier started accelerating. But whether those changes penetrated deep into Greenland’s interior remained largely unresolved.

      “We’ve mostly concerned ourselves with the margins,” says atmosphere-cryosphere scientist Jenny Turton of the nonprofit Arctic Frontiers in Tromsø, Norway, who was not involved in the new study. That’s where the most dramatic changes with the greatest impacts on sea level rise have been observed, she says (SN: 4/30/22, SN: 5/16/13).

      Keen to measure small rates of movement in the ice stream far inland, Khan and his colleagues used GPS, which in the past has exposed the tortuous creeping of tectonic plates (SN: 1/13/21). The team analyzed GPS data from three stations along the ice stream’s main trunk, all located between 90 and 190 kilometers inland.

      The data showed that the ice stream had accelerated at all three points from 2016 to 2019. In that time frame, the ice speed at the station farthest inland increased from about 344 meters per year to surpassing 351 meters per year.

      The researchers then compared the GPS measurements with data collected by polar-orbiting satellites and aircraft surveys. The aerial data agreed with the GPS analysis, revealing that the ice stream was accelerating as far as 200 kilometers upstream. What’s more, shrinking — or thinning — of the ice stream that started in 2011 at Zachariae Isstrøm had propagated more than 250 kilometers upstream by 2021. 

      “This is showing that glaciers are responding along their length faster than we had thought previously,” says Leigh Stearns, a glaciologist from the University of Kansas in Lawrence, who was not involved in the study.

      Khan and his colleagues then used the data to tune computer simulations that forecast the ice stream’s impact on sea level rise. The researchers predict that by 2100, the ice stream will have singlehandedly contributed between about 14 to 16 millimeters of global sea level rise — as much as Greenland’s entire ice sheet has in the last 50 years.

      The findings suggest that past research has probably underestimated rates of sea level rise due to the ice stream, Stearns and Turton say. Similarly, upstream thinning and acceleration in other large ice flows, such as those associated with Antarctica’s shrinking Pine Island and Thwaites glaciers, might also cause sea levels to rise faster than expected, Turton says (SN: 6/9/22, SN: 12/13/21).

      Khan and his colleagues plan to investigate inland sections of other large ice flows in Greenland and Antarctica, with the hopes of improving forecasts of sea level rise (SN: 1/7/20).

      Such forecasts are crucial for adapting to climate change, Stearns says. “They’re helping us better understand the processes so that we can inform the people who need to know that information.” More

    • 125 Shares189 Views

      in Heart

      Wind turbines could help capture carbon dioxide while providing power

      by

      Wind turbines could offer a double whammy in the fight against climate change.

      Besides harnessing wind to generate clean energy, turbines may help to funnel carbon dioxide to systems that pull the greenhouse gas out of the air (SN: 8/10/21). Researchers say their simulations show that wind turbines can drag dirty air from above a city or a smokestack into the turbines’ wakes. That boosts the amount of CO2 that makes it to machines that can remove it from the atmosphere. The researchers plan to describe their simulations and a wind tunnel test of a scaled-down system at a meeting of the American Physical Society’s Division of Fluid Dynamics in Indianapolis on November 21.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      Addressing climate change will require dramatic reductions in the amount of carbon dioxide that humans put into the air — but that alone won’t be enough (SN: 3/10/22). One part of the solution could be direct air capture systems that remove some CO2 from the atmosphere (SN: 9/9/22).

      But the large amounts of CO2 produced by factories, power plants and cities are often concentrated at heights that put it out of reach of machinery on the ground that can remove it. “We’re looking into the fluid dynamics benefits of utilizing the wake of the wind turbine to redirect higher concentrations” down to carbon capture systems, says mechanical engineer Clarice Nelson of Purdue University in West Lafayette, Ind.

      As large, power-generating wind turbines rotate, they cause turbulence that pulls air down into the wakes behind them, says mechanical engineer Luciano Castillo, also of Purdue. It’s an effect that can concentrate carbon dioxide enough to make capture feasible, particularly near large cities like Chicago.

      “The beauty is that [around Chicago], you have one of the best wind resources in the region, so you can use the wind turbine to take some of the dirty air in the city and capture it,” Castillo says. Wind turbines don’t require the cooling that nuclear and fossil fuel plants need. “So not only are you producing clean energy,” he says, “you are not using water.”

      Running the capture systems from energy produced by the wind turbines can also address the financial burden that often goes along with removing CO2 from the air. “Even with tax credits and potentially selling the CO2, there’s a huge gap between the value that you can get from capturing it and the actual cost” that comes with powering capture with energy that comes from other sources, Nelson says. “Our method would be a no-cost added benefit” to wind turbine farms.

      There are probably lots of factors that will impact CO2 transport by real-world turbines, including the interactions the turbine wakes have with water, plants and the ground, says Nicholas Hamilton, a mechanical engineer at the National Renewable Energy Laboratory in Golden, Colo., who was not involved with the new studies. “I’m interested to see how this group scaled their experiment for wind tunnel investigation.” More

    • 88 Shares109 Views

      in Heart

      Landslides shaped a hidden landscape within Yellowstone

      by

      DENVER — A hidden landscape riddled with landslides is coming into focus in Yellowstone National Park, thanks to a laser-equipped airplane.

      Scientists of yore crisscrossed Yellowstone on foot and studied aerial photographs to better understand America’s first national park. But today researchers have a massive new digital dataset at their fingertips that’s shedding new light on this nearly 1-million-hectare natural wonderland.

      These observations of Yellowstone have allowed a pair of researchers to pinpoint over 1,000 landslides within and near the park, hundreds of which had not been mapped before, the duo reported October 9 at the Geological Society of America Connects 2022 meeting. Most of these landslides likely occurred thousands of years ago, but some are still moving.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      Mapping Yellowstone’s landslides is important because they can cripple infrastructure like roadways and bridges. The millions of visitors that explore the park each year access Yellowstone through just a handful of entrance roads, one of which recently closed for months following intense flooding.

      In 2020, a small aircraft flew a few hundred meters above the otherworldly landscape of Yellowstone. But it wasn’t ferrying tourists eager for up close views of the park’s famous wolves or hydrothermal vents (SN: 7/21/20, SN: 1/11/21). Instead, the plane carried a downward-pointing laser that fired pulses of infrared light at the ground. By measuring the timing of pulses that hit the ground and reflected back toward the aircraft, researchers reconstructed the precise topography of the landscape.

      Such “light detection and ranging,” or lidar, data reveal details that often remain hidden to the eye. “We’re able to see the surface of the ground as if there’s no vegetation,” says Kyra Bornong, a geoscientist at Idaho State University in Pocatello. Similar lidar observations have been used to pinpoint pre-Columbian settlements deep within the Amazon jungle (SN: 5/25/22).

      The Yellowstone lidar data were collected as part of the 3D Elevation Program, an ongoing project spearheaded by the United States Geological Survey to map the entirety of the United States using lidar.

      Bornong and geomorphologist Ben Crosby analyzed the Yellowstone data — which resolve details as small as about one meter — to home in on landslides. The team searched for places where the landscape changed from looking relatively smooth to looking jumbled, evidence that soil and rocks had once been on the move. “It’s a pattern-recognition game,” says Crosby, also of Idaho State University. “You’re looking for this contrast between the lumpy stuff and the smooth stuff.”

      The researchers spotted more than 1,000 landslides across Yellowstone, most of which were clustered near the periphery of the park. That makes sense given the geography of Yellowstone’s interior, says Lyman Persico, a geomorphologist at Whitman College in Walla Walla, Wash., who was not involved in the research. The park sits atop a supervolcano, whose previous eruptions blanketed much of the park in lava (SN: 1/2/18). “You’re sitting in the middle of the Yellowstone caldera, where everything is flat,” says Persico.

      But steep terrain also abounds in the national park, and there’s infrastructure in many of those landslide-prone areas. In several places, the team found that roads had been built over landslide debris. One example is Highway 191, which skirts the western edge of Yellowstone.

      An aerial image of U.S. Highway 191 near Yellowstone shows barely perceptible signs of a long-ago landslide. But laser mapping reveals the structure and extent of the landslide in much greater detail (use the slider to compare images). It’s one of more than 1,000 landslides uncovered by new maps.

      It’s worth keeping an eye on this highway since it funnels significant amounts of traffic through regions apt to experience landslides, Bornong says. “It’s one of the busiest roads in Montana.”

      There’s plenty more to learn from this novel look at Yellowstone, Crosby says. Lidar data can shed light on geologic processes like volcanic and tectonic activity, both of which Yellowstone has in spades. “It’s a transformative tool,” he says. More

    • 175 Shares199 Views

      in Heart

      Heat waves in U.S. rivers are on the rise. Here’s why that’s a problem

      by

      U.S. rivers are getting into hot water. The frequency of river and stream heat waves is on the rise, a new analysis shows.

      Like marine heat waves, riverine heat waves occur when water temperatures creep above their typical range for five or more days (SN: 2/1/22). Using 26 years of United States Geological Survey data, researchers compiled daily temperatures for 70 sites in rivers and streams across the United States, and then calculated how many days each site experienced a heat wave per year. From 1996 to 2021, the annual average number of heat wave days per river climbed from 11 to 25, the team reports October 3 in Limnology and Oceanography Letters.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      The study is the first assessment of heat waves in rivers across the country, says Spencer Tassone, an ecosystem ecologist at the University of Virginia in Charlottesville. He and his colleagues tallied nearly 4,000 heat wave events — jumping from 82 in 1996 to 198 in 2021 — and amounting to over 35,000 heat wave days. The researchers found that the frequency of extreme heat increased at sites above reservoirs and in free-flowing conditions but not below reservoirs — possibly because dams release cooler water downstream.

      Most heat waves with temperatures the highest above typical ranges occurred outside of summer months between December and April, pointing to warmer wintertime conditions, Tassone says.

      Human-caused global warming plays a role in riverine heat waves, with heat waves partially tracking air temperatures — but other factors are probably also driving the trend. For example, less precipitation and lower water volume in rivers mean waterways warm up easier, the study says.

      “These very short, extreme changes in water temperature can quickly push organisms past their thermal tolerance,” Tassone says. Compared with a gradual increase in temperature, sudden heat waves can have a greater impact on river-dwelling plants and animals, he says. Fish like salmon and trout are particularly sensitive to heat waves because the animals rely on cold water to get enough oxygen, regulate their body temperature and spawn correctly.

      There are chemical consequences to the heat as well, says hydrologist Sujay Kaushal of the University of Maryland in College Park who was not involved with the study. Higher temperatures can speed up chemical reactions that contaminate water, in some cases contributing to toxic algal blooms (SN: 2/7/18). 

      The research can be used as a springboard to help mitigate heat waves in the future, Kaushal says, such as by increasing shade cover from trees or managing stormwater. In some rivers, beaver dams show promise for reducing water temperatures (SN: 8/9/22). “You can actually do something about this.” More

    • 113 Shares199 Views

      in Heart

      Tree-climbing carnivores called fishers are back in Washington’s forests

      by

      Holding an antenna above his head, Jeff Lewis crept through an evergreen forest in the Cascade mountains, southeast of Seattle. As he navigated fallen fir logs and dripping ferns, he heard it: a faint “beep” from a radio transmitter implanted in an animal code-named F023.

      F023 is a fisher (Pekania pennanti), an elusive member of the weasel family that Lewis fondly describes as a “tree wolverine.” Resembling a cross between a cat and an otter, these sleek carnivores hunt in forests in Canada and parts of the northern United States. But fur trapping and habitat loss had wiped out Washington’s population by the mid-1900s.

      Back in 2017 when Lewis was keeping tabs on F023, he tracked her radio signal from a plane two or three times a month, along with dozens of other recently released fishers. Come spring, he noticed that F023’s behavior was different from the others.

      Her locations had been clustered close together for a few weeks, a sign that she might be “busy with babies,” says Lewis, a conservation biologist with the Washington Department of Fish and Wildlife. He and colleagues trekked into the woods to see if she had indeed given birth. If so, it would be the first wild-born fisher documented in the Cascades in at least half a century.

      As the faint beeps grew louder, the biologists found a clump of fur snagged on a branch, scratch marks in the bark and — the best clue of all — fisher scat. The team rigged motion-detecting cameras to surrounding trees. A few days later, after sifting through hundreds of images of squirrels and deer, the team hit the jackpot: a grainy photo of F023 ferrying a kit down from her den high in a hemlock tree. The scientists were ecstatic.

      “We’re all a bunch of little kids when it comes to getting photos like that,” Lewis says.

      Sign Up For the Latest from Science News

      Headlines and summaries of the latest Science News articles, delivered to your inbox

      Thank you for signing up!

      There was a problem signing you up.

      Chasing babies

      This notable birth came during the second phase of a 14-year fisher reintroduction effort. After 90 fishers were released in Olympic National Park from 2008 to 2010, the project turned its focus east of Seattle, relocating 81 fishers in the South Cascades (home to Mount Rainier National Park) from 2015 to 2020, and then 89 fishers in the North Cascades from 2018 to 2020. The animals were brought in from British Columbia and Alberta. The project concluded last year, when researchers let loose the final batch of fishers.

      Baby animals are the key measure of success for a wildlife reintroduction project. As part of Washington’s Fisher Recovery Plan, biologists set out to document newborn kits as an indicator of how fishers were faring in the three relocation regions.

      Before F023’s kit was caught on camera in May 2017, biologists had already confirmed births by seven relocated females on the Olympic Peninsula, where the whole project began. Two of the seven females had four kits, “the largest litter size ever documented on the West Coast,” says Patti Happe, wildlife branch chief at Olympic National Park. Most females have one to three kits.

      Lewis is often asked, why put all of this effort into restoring a critter many people have never heard of? His answer: A full array of carnivores makes the ecosystem more resilient.

      Happe admits to another motive: “They’re freaking adorable — that’s partly why we’re saving them.”

      This agile member of the weasel family is a fearsome predator. Fishers are one of the few carnivores that can hunt and kill quill-covered porcupines.EMILY BROUWER/NPS (CC BY 2.0)

      The missing piece

      Contrary to their name, fishers don’t hunt fish, though they’ll happily munch on a dead one if it’s handy. They mainly prey on small mammals, but they also eat reptiles, amphibians, insects, fruit and carrion. About a meter long, males weigh up to six kilograms, about twice as much as females. Fun facts: Females raise young high above the forest floor in hollowed-out spaces in tree trunks. Fishers can travel face-first down tree trunks by turning their hind feet 180 degrees. They have wickedly sharp teeth and partially retractable claws. And they’re incredibly agile, leaping up to two meters between branches and traveling as much as 30 kilometers in a day.

      Fishers’ stubby legs and unique climbing skills make them a threat to tree-climbing porcupines. It isn’t pretty: A fisher will force the quill-covered animal down a tree and attack its face until it dies from blood loss or shock. Then the fisher neatly skins the prickly prey, eating most everything except the quills and bones.

      These camera trap photos, taken in April 2021, show female fisher F105 carrying one of her four kits down from her tree den near Lake Wenatchee in the North Cascades.NPS

      But these fearsome predators were no match for humans. In the 1800s, trappers began targeting fishers for their fur. Soft and luxuriant, the glossy brown-gold pelts were coveted fashion accessories, selling for as much as $345 each in the 1920s. This demand meant fishers disappeared not only from Washington, but from more than a dozen states across the northern United States. Once fisher populations plummeted, porcupines ran rampant across the Great Lakes region and New England. This wreaked havoc on forests because the porcupines gobbled up tree seedlings.

      Hoping to keep porcupine populations in check, private timber companies partnered with state agencies to bring fishers back to several states in the 1950s and 1960s. Thanks to these efforts and stricter trapping regulations, fishers are once again abundant in Michigan, Wisconsin, New York and Massachusetts.

      But in Washington, like most of the West, fisher numbers were still slim. By the turn of the 21st century, no fisher had been sighted in the state for over three decades.

      As in the Midwest and New England, private timber companies in Washington supported bringing back fishers. Although porcupines are uncommon in Washington, mountain beavers — a large, primitive rodent endemic to the Pacific Northwest — fill a similar role in Washington’s evergreen forests: They eat tree seedlings. And fishers eat them.

      By 2006, the state hatched a plan to bring the animals in from Canada. “It was a big opportunity to restore a species,” Lewis says. “We can fix this.”

      [embedded content]
      This 2009 camera trap vídeo from Olympic Peninsula shows fisher F007 scaling a cedar tree and carrying her four kits to the forest floor, one at a time

      A new home

      Like the other Canadian fishers moved to Washington, F023’s relocation story began when she walked into a box trap in British Columbia, lured by a tasty morsel of meat. The bait had been set by local trappers hired by Conservation Northwest, a nonprofit that is one of the recovery project’s three main partners, along with Washington Fish and Wildlife and the National Park Service. After veterinarians checked her health and administered vaccines and antiparasitics to help her survive in her new home, F023 received a surgically implanted radio transmitter and was driven across the border.

      She was met by members of the fisher recovery team, who released her just south of Mount Rainier National Park. The forest’s towering Douglas fir, western red cedar and western hemlock trees were full of cubby holes and cavities to hide in, and the undergrowth held plenty of small mammals to eat. At the release, upward of 150 people gathered around F023’s box, part of the team’s effort to engage the public in championing fisher recovery. Everyone cheered as a child opened the door and the furry female bounded into the snowy woods, out of sight in a flash.

      The team monitored each relocated fisher for up to two years to see if the project met key benchmarks of success in each of the three regions: more than 50 percent of the fishers surviving their first year, at least half establishing a home range near the release site, and a confirmed kit born to at least one female.

      “We met those marks,” says Dave Werntz, science and conservation director at Conservation Northwest.

      The effort may have been aided by a series of bypasses built over and under a roughly 25-kilometer stretch of Interstate 90 east of Seattle. One of these structures is the largest wildlife bridge in North America, an overpass “paved” with forest. In 2020, a remote camera caught an image of what looks like a fisher moving through one of the underpasses.

      Speeding vehicles on busy highways pose a threat to fishers and other migrating wildlife. This new bridge east of Seattle is “paved” with trees and plants to let animals safely cross I-90 to find habitat, food or mates on the other side.WASHINGTON STATE DEPT. OF TRANSPORTATION

      “Male fishers go on these huge walkabouts to find females,” Werntz says. While biologists assumed fishers would cross the freeway to search for mates, having photographic proof “is pretty wonderful,” he says.

      Happe and others hope to also see wildlife crossings along Interstate 5 one day. The freeway, which runs north-south near the coast, is the main obstacle keeping the Olympic and Cascade populations apart, she says. “We’re all working on wildlife travel corridors and connectivity in hopes the two populations hook up.”

      Learning curve

      The majority of the initial 90 fishers relocated to the Olympic Peninsula settled nicely into their new homes, according to radio tracking. In the year following release in that location, the fisher survival rate averaged 73 percent, but varied based on the year and season they were released, as well as sex and age of the fishers.

      Males fared better than females: Seventy-four percent of recorded deaths were of females, partly because they are smaller and more vulnerable to predators, such as bobcats and coyotes. Of 24 recovered carcasses where cause of death could be determined, 14 were killed by predators, seven were struck by vehicles, two drowned and one died in a leg-hold trap, Lewis, Happe and colleagues reported in the April 2022 Journal of Wildlife Management.

      Because the first fishers relocated to the Olympic Peninsula were released in several locations, the animals had trouble finding mates. As a result, only a few parents sired the subsequent generations.

      The researchers became concerned when they looked at the genetic diversity of fishers on the Olympic Peninsula six years post-relocation. Happe and colleagues set up 788 remote cameras and hair-snare stations: triangular cubbies open on either end with a chicken leg as bait in the middle and wire brushes protruding from either side to grab strands of fur. DNA analysis of the fur raised red flags about inbreeding, Happe and Lewis say.

      “Models showed we were going to lose up to 50 percent of genetic diversity, and the population would wink out in something like 100 years,” Happe says. To expand the gene pool, the team brought 20 more fishers to the Olympic Peninsula in 2021. These animals came from Alberta whereas the founding population had hailed from British Columbia.

      [embedded content]
      Two fishers from Canada are released from wooden crates, quickly disappearing into Olympic National Park in November 2021. Both wear radio tracking devices so that researchers can monitor their well-being.

      As the reintroduction effort moved into the Cascades, the team adapted, based on lessons learned from the Olympic Peninsula. For instance, to increase the likelihood of fishers finding each other more quickly, the animals were released at fewer sites that were closer together. The team also released the animals before January, giving females ample time to settle into a home range before the spring mating and birthing season.

      Finding their food

      As the experiment went on, more unanticipated findings popped up. Fishers released in the southern part of the Cascades were more likely to survive the first year (76 percent) than those relocated north of I-90 (40 percent), according to the final project report, released in June. Remote-camera data suggest that’s because there are less prey and slightly more predators in the North Cascades, says Tanner Humphries, community wildlife monitoring program lead for Conservation Northwest.

      And in both the Cascades and the Olympic Peninsula, fishers are using different types of habitat than biologists had predicted, Happe says. The mammals — once assumed to be old-growth specialists — are using a mosaic of young and old forests. Fishers require large, old trees with cavities for denning and resting. But in younger managed forests where trees are thinned or cut, prey may be easier to come by.

      Live traps in the South Cascades support that idea. Fishers’ preferred prey — snowshoe hares and mountain beavers — were most abundant in young regenerating forests. In older forests, traps detected mainly mice, voles and chipmunks, which are not substantial meals for fishers, Mitchell Parsons, a wildlife ecologist at Utah State University in Logan, reported with Lewis, Werntz and others in 2020 in Forest Ecology and Management.

      North America’s fisher populations are blossoming, helping to rebalance forest ecosystems.Emily Brouwer/NPS (CC BY 2.0)

      The future is re-wild

      After F023’s baby was caught on camera five years ago, the mother’s tracking chip degraded as designed — the hardware lasts less than two years. Since then, many more fisher kits have been born in Washington.

      In fact, these furry carnivores are one of the most successfully translocated mammals in North America. According to Lewis, 41 different translocation efforts across the continent have helped fisher populations blossom. The animals now occupy 68 percent of their historical range, up from 43 percent in the mid-1900s.

      With the last batch of fishers delivered to Washington in 2021, the relocation phase of the project has ended. Lewis, Happe and their partners plan to continue monitoring how these sleek tree-climbing carnivores are faring — and how the ecosystem is responding. For instance, fishers are indeed feasting on seedling-eating mountain beavers, according to research reported by Happe, Lewis and others in 2021 in Northwestern Naturalist.

      Given climate change, species loss and ecosystem degradation, animals worldwide face difficult challenges. The fact that fishers are thriving once again in Washington offers hope, Lewis says.

      “It’s a hard time, it’s a hard world, and this feels like something we’re doing right,” he says. “Instead of losing something, we’re getting it back.” More