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Beavers Will Save California's Endangered Salmon

California’s record-breaking drought has been catastrophic for the state’s wild salmon, whose numbers have fallen to record lows. But fostering fish populations might be as easy as letting beavers do their thing.

by Lauren Rothman
Feb 20 2015, 7:31pm

Photo via Flickr user Paul Stevenson

California's record-breaking drought hasn't been kind to the state's many farmers, ranchers, or even its fire stations and high schools, the latter two having fallen victim to water theft as the precious liquid becomes ever more scarce in the Golden State. And the water shortage has been especially catastrophic for the state's population of wild salmon, which in recent years has fallen to record lows: it's believed that only 1 percent of the state's historic population still exists. That's crappy news for Californians craving a nice, wild-caught salmon filet, and even worse news for the state's salmon fishermen, whose catches normally bring in $1.5 million per year.

Salmon—the two species that run Northern California's rivers are the Coho and the Chinook—thrive in deep, cool, slow-moving waters. But a combination of factors—historical logging, the conversion of floodplains into agricultural lands, and the diversion of river water for use on the state's farms, both legal and illicit—have literally left the fish high and dry. With streambed levels at an all-time low last summer, salmon eggs couldn't survive the hot, shallow water, and over 95 percent of the fish roe in Northern California streams didn't survive the season.

READ: Your Weed Habit Could Be Killing Off California Salmon

Things are looking bad for one of the state's most valued resources, which has populated California waters for thousands of years and whose historical runs, or upriver migrations from the sea, are estimated at about six million; by contrast, last fall's run of Chinook was tallied at around 635,000. But increasingly, scientists, researchers, and citizens are coming to the conclusion that one possible solution for the fish's plight is low-cost and 100-percent natural: beavers, and the dams they build.

Dr. Michael Pollock, an ecosystems analyst at the National Oceanic and Atmospheric Administration's fisheries department, says there's no doubt in his mind that beavers are key to the rebound of California salmon populations. Pollock's work examining the links between beaver dams and the salmon-sheltering habitats they create for Pacific Northwest fish populations has been seminal: his first paper on the topic was published in 2004. And as interest in his research has picked up in California, he's been traveling up and down the state giving presentations on how the architectural work of the cute, furry, but historically reviled semi-aquatic rodents has major potential to efficiently rebuild the salmon populations that are important to so many eaters across California.

Research has shown that the slow-moving waters along beaver-dammed streams produce juvenile salmon that are larger and healthier.

As Pollock explains, the state's historical topography has been drastically altered over time. Its waterways, once full of the deep, still pools that are the ideal habitat for juvenile salmon—providing the low temperatures the fish thrive in as well as attracting the insects they feed on—have been broken up as forests have been logged, floodplains drained for conversion into farmland, and beaver dams destroyed under the misconception that the structures blocked the fish's movements (they don't).

"A lot of people have viewed streams as highways for fish, rather than homes for fish," Pollock says. "The thinking has been, 'All streams need to be passable to fish at all times.' But that's not really how streams work," he says. Research has shown that the slow-moving waters along beaver-dammed streams produce juvenile salmon that are larger, healthier, and better equipped to survive their downstream journeys to the ocean, where they spend most of their adult lives before returning to their natal rivers to spawn.

Human alteration of California's landscape has gone hand in hand with the destruction of the beaver. In the 1800s, the state's beaver population was hunted nearly to extinction thanks to the thriving fur trade, and even in more recent times, some farmers and ranchers have routinely eliminated the rodents from their properties, as the animals' dammed ponds can sometimes flood fields, wash out roads, and drown trees. But the correlation between the reduction of the beaver population and the downfall of California salmon is unmistakable, and it's one that local Native American tribes have been aware of for hundreds of years.

'What does the river mean to us?' McConnell asks. 'It is, in a sentence, the lifeblood of our people.'

"The beaver are definitely considered a 'cultural keystone' species," says Sarah Beesley, a fisheries biologist with the Yurok Tribe of northwest California, who have lived along the area's Klamath River "since time immemorial," according to Bob McConnell, the tribe's heritage preservation officer. "Coho will actively seek out beaver ponds," Beesley says. "It's their preferred habitat."

The Yurok Tribe is the largest aboriginal tribe in the state of California, with approximately 6,000 enrolled members. The tribe's reservation lands encompass a strip of land one mile wide on each side of the Klamath River, from just upstream of its confluence with the Trinity River at Weitchpec, California, to its mouth at the Pacific Ocean. In conjunction with the Karuk Tribe of the upper Klamath as well as the Mid Klamath Watershed Council, the Yurok's fishery department is actively engaged in projects that will help foster beaver populations and, in turn, repopulate Klamath waters with vitally important Coho and Chinook salmon. They're doing this primarily by building complex wood jams to facilitate a number of ecological functions, and excavating off-channel wetland habitats to mimic beaver ponds. This approach facilitates the processes that form and maintain productive salmon habitats. The hope is that by building back habitat complexity and natural processes will attract beavers, who will begin building dams.

"Their work starts to take over our job," Beesley says.

Fresh-caught salmon is a sought-after addition to restaurant menus all over the Pacific Northwest, but it's no exaggeration to say that its availability is a matter of life or death to the Yurok people.

"What does the river mean to us?" McConnell asks. "It is, in a sentence, the lifeblood of our people."

Rosie Clayburn, the tribe's cultural resource manager, elaborates.

"It's how we provide food for our families," she says.

McConnell notes that at one time, the Lower Klamath supported the third-largest run of salmon on the West Coast. The fish were so central to the Yurok diet, Clayburn adds, that there was a traditional ceremony celebrating the first salmon's entry into the river at the beginning of spawning season. But because of the salmon's precipitous decline, that ceremony has been lost. And the Yuroks' health has declined in tandem with the fish.

"We're not as healthy as we used to be," McConnell says. "The majority of our members don't have access to fresh fish, and as a result, we have high levels of diabetes, high numbers of overweight people."

But the Yurok are hopeful that their continued efforts to restore beaver habitats will help the salmon and, in turn, help their members.

"Without the beavers, it's very difficult to get salmon back," Beesley said.