Tag: salmon

Could an Alaska mining project jeopardize Earth’s largest bald eagle gathering?

High Country News article about our lab’s work in Alaska.

… By late morning, eagles are all around us. “Look at that eagle party across the way,” says Taal Levi, a wildlife ecologist with the Cary Institute of Ecosystem Studies, whose tales of this ecological mother lode inspired Wheat’s doctoral project. He points to 50-plus eagles bunched in cottonwoods beyond the river, explaining that since they’re not breeding, they’re less territorial. “Though they do like to steal from each other.”

As if on cue, an adult chases a young bird from some bait near a remote-controlled net gun, and bingo — Lewis flips the switch. Like a starter’s pistol at a track meet, the gun’s crack sends us dashing toward our catch.

Lewis carefully extracts feathers from the netting. He pops a hood over the giant raptor’s head, covers its shiny black talons with handmade leather booties, then hands the bird to Wheat, who cradles it against her chest as she heads back to the road.

At almost 15 pounds, it’s clear we’ve got a female. She’s fearsome, with a massive hooked beak and flesh-shredding talons that curl around Lewis’ exposed fingertips after he takes off a bootie to give us a peek. Yet she sits calmly as Lewis threads a Teflon harness with the GPS under her wings and around her chest, positioning the device just behind her head. Her breast feathers feel silky and warm against the frosty air.

Wheat clips a few of them for stable isotope analysis, which ecologists have long used to infer an animal’s diet based on the levels of carbon and nitrogen. Wherever birds forage, the elements in the food suffuse their feathers as they grow. Wheat hopes the approach, tested in songbirds but not eagles, will tell her where the migrants lived and fed before she tagged them.

Read the whole article here.

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More coastal salmon spawning helps grizzlies and fisheries

From Conservation Magazine, a short article on our recent PLoS Biology article:

Letting more salmon escape fisheries along the coast could boost both grizzly bear populations and fishery yields, according to a new study in PLoS Biology.

Fishery managers already let a certain number of salmon slip away so those fish can spawn. But it’s not clear which “escapement” level is best for the fisheries and the ecosystem. Grizzly bears eat salmon and often leave the remains of their meals by streams, providing nutrients for plants and animals. And the number of spawning fish also affects fishery yields down the line.

Researchers tackled the problem by modelling the effects of different escapement levels for four coastal sockeye salmon stocks and two inland stocks in Alaska and British Columbia, Canada. In the coastal systems, leaving more salmon to spawn would increase bear density by 8 to 44 percent. Fishery yields would jump as well — “an apparent win-win situation,” the authors write.

Read the full article here.

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Let Them Run

From Conservation Magazine, a nice little article on our recent paper in Conservation Letters calling for a small number of fully protected salmon runs.

Ask not what a park can do for spawning salmon. Ask what robust salmon runs could do for the park – and for coastal fishing communities.

That’s the provocative idea behind a “radical” proposal being floated by a group of conservation biologists. Limiting fishing for some pink and chum salmon bound for spawning streams in British Columbia parks could reinvigorate ecosystems that thrive on the annual infusion of millions of fish carcasses. And, in the long run, protecting the runs could produce economic benefits by making ecosystems more productive and resilient to change.

“Although managers safeguard protected areas for migratory species, little consideration has been given to how migratory species might benefit parks,” a team led by Chris Darimont of the University of California, Santa Cruz, and the Raincoast Conservation Foundation in Canada write in Conservation Letters. Case in point: Headwaters streams in coastal parks in British Columbia once saw huge annual runs of Pacific salmon. Many of the spawned-out fish died, producing a “fertilizer effect” that pumped a vast pulse of nutrients into surrounding ecosystems. “The breakdown of salmon carcasses…  ultimately can affect communities of riparian plants, terrestrial and freshwater invertebrates, resident fish, and songbirds,” the authors note. These days, however, commercial and recreational fishers kill up to 90% of the fish before they can spawn, blocking the transfer of nutrients.

To restore at least part of that pulse, the authors propose limiting catches of pink and chum salmon(Oncorhynchus gorbuscha and keta), which have still have large runs but low commercial value. While Chinook salmon sold for $1.23 a pound in 2002, for instance, pink and chum sold for just 6 to 16 cents a pound. “We believe that a focus on pink and chum… provides opportunity to implement our ideas without severe economic consequences.”

The authors concede that “some might deem our idea politically unachievable,” but add that their “aim is to inform and inspire decision-makers with a plan that not only favors biodiversity but also one that ultimately might yield economic and management benefits. Our goal is to inoculate the literature with a provocative idea to stimulate discussion.”

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