Tossing salmon for science

A decades-long experiment demonstrates how the iconic fish help trees grow.

  • Andrea Odell, an undergraduate student in the UW School of Aquatic and Fishery Sciences, tosses dead sockeye salmon onto the bank of Hansen Creek in southwest Alaska while other researchers record data and look for salmon in the stream.

    Dan DiNicola/University of Washington
  • Both live sockeye salmon and fish carcasses are seen in Hansen Creek in 2014.

    Tom Quinn/University of Washington
  • Alex Lincoln, a graduate student in the UW School of Aquatic and Fishery Sciences, carries fish that have died in Hansen Creek. The fish were thrown on the creek's left bank (looking downstream) as part of the research team's protocol.

    Dan DiNicola/University of Washington
  • Sam May, a graduate student in the UW School of Aquatic and Fishery Sciences, measures sockeye salmon carcasses.

    Dan DiNicola/University of Washington
  • Researchers tag sockeye salmon.

    Dennis Wise/University of Washington
  • UW researchers walk along Hansen Creek in southwest Alaska this August.

    Dan DiNicola/University of Washington
  • Kyla Bivens, an undergraduate student in the UW School of Aquatic and Fishery Sciences, uses a hooked pole to throw a dead sockeye salmon onto the bank.

    Dan DiNicola/University of Washington
  • Sarah Schooler, a UW undergraduate student at the time, and Martini Arostegui, a UW doctoral student in the School of Aquatic and Fishery Sciences, at the mouth of Hansen Creek in 2015.

    Dennis Wise/University of Washington
  • Tom Quinn, Sarah Schooler, and Martini Arostegui, walk along Hansen Creek in southwest Alaska in 2015.

    Dennis Wise/University of Washington
  • Blakeley Adkins snips spruce needles along Hansen Creek for the study's chemical analysis.

    Catherine Austin/University of Washington
  • Researchers measure trees along the creek.

    Catherine Austin/University of Washington
 

Every year thousands of sockeye salmon meet their end in Hansen Creek, a pebble-strewn tributary of Lake Aleknagik in southwestern Alaska, whether from old age or at the paws and jaws of a brown bear. Either way, they’re almost certainly destined to rot away on the north-facing bank of the stream.

That’s because professors, researchers and students have been systematically tossing their carcasses to that side of the creek for the last 20 years. The scientists count and measure the carcasses and then toss them out of the streambed and up into the forest using wooden poles with metal hooks on the end, called gaffs. In total, they tossed about 295 tons of salmon onto Hansen Creek’s north-facing bank to avoid double counting surveyed fish. In doing so, they have created a unique opportunity to study exactly how salmon fertilize the forest. 

Over the past 20 years, researchers across the Northwest have shown that salmon play an essential role in forests: Trees next to salmon-bearing streams appear to grow better than their salmon-deprived counterparts, and the nutrients salmon bring from the ocean make their way into the needles and wood of trees. But this experiment, described in a recently published paper, led by Tom Quinn, a professor in the School of Aquatic and Fishery Sciences at the University of Washington, proves a basic fact: More salmon means faster growing trees.

Quinn, who has been teaching and researching in southwestern Alaska since the late 1980s, initially studied the relationship between bear predation and salmon populations. Over the years, his work and the work of his collaborators and students has branched out to address other questions, like how climate change and hatchery fish affect the environment. “What’s special here is this is a long-term experiment,” Quinn said. “It’s part of a more holistic study of interactions throughout the ecosystem.”

In the summer of 2016, two decades after the fish-tossing began, Quinn, along with co-authors James Helfield, Catherine Austin, Rachel Hovel and Andrew Bunn, took tree core samples from the spindly white spruce that grow on either side of Hansen Creek. “In the back of my mind I’ve been thinking about the fertilization impact,” Quinn said. It seemed like the right time to finally see what the effect was: “I’m not going to be doing this forever. Twenty years seemed like a good time to analyze the data.” The core samples revealed that the fertilized trees had grown faster in the salmon guts than they had grown in the twenty years prior to the experiment, and were starting to catch up with their taller counterparts on the opposite bank.

With control over the conditions, the researchers were able to address some of the criticisms of previous studies. Most studies in the past measured the difference in growth rates of trees above and below waterfalls or between different streams, Quinn said. And in doing so they weren’t able to rule out other potential causes: Water availability, elevation, and other factors impacting soil fertility. Quinn’s somewhat accidental experiment removed many of those factors.

The research reinforced salmon’s importance in the ecosystem, even as their stocks dwindle in many streams up and down the West Coast. This study, Quinn said, “provides perspective on what is lost in other ecosystems.”

Carl Segerstrom is an editorial fellow for High Country News. Email him at [email protected] or submit a letter to the editor

High Country News Classifieds
  • COMMUNITY ENGAGEMENT DIRECTOR
    Colorado Wild Public Lands (COWPL), based in Basalt, is an exciting nonprofit working to keep public lands open and accessible. Our growing organization is seeking...
  • BUSINESS SUPPORT ASSISTANT (PART-TIME)
    High Country News, an award-winning media organization covering the communities and environment of the Western United States, seeks a part-time business support assistant to provide...
  • SOCIAL MEDIA AND DIGITAL ADVERTISING SPECIALIST
    The Southern Utah Wilderness Alliance (SUWA), Utah's largest conservation organization, has an immediate opening for a full-time Social Media and Digital Advertising Specialist. This position...
  • SPRING-FED PARCELS ON THE UPPER SAC RIVER
    Adjacent parcels above the Upper Sacramento river, near Dunsmuir. The smaller is just under 3 acres, with the larger at just under 15 acres. Multiple...
  • DEVELOPMENT COORDINATOR
    Greater Yellowstone Coalition seeks a development professional to coordinate the organization's individual giving program. The position description is available at http://greateryellowstone.org/careers Please email a letter...
  • IDAHO STATE DIRECTOR
    The Wilderness Society is seeking a full time Idaho State Director who will preferably be based in Boise, Idaho. At least 8-10 years of experience...
  • COMMUNICATIONS MANAGER AND BEARS EARS EDUCATION CENTER MANAGER
    Conservation nonprofit Friends of Cedar Mesa in Bluff, Utah is hiring for two positions. We seek a Communications Manager to execute inspiring and impactful communications...
  • EXECUTIVE DIRECTOR
    Wilderness Volunteers Wilderness Volunteers (WV), a 24-year leader in preserving our nation's wildlands, is seeking a motivated person with deep outdoor interests to guide our...
  • HECHO POLICY AND ADVOCACY MANAGER
    Hispanics Enjoying Camping, Hunting, and the Outdoors (HECHO) was created in 2013 to help fulfill our duty to conserve and protect our public lands for...
  • FISHERIES BIOLOGIST
    Under the direct supervision of the Director of Shoshone-Paiute Tribe's Fish, Wildlife & Parks, in coordination with the Tribal Programs Administrator and the Tribal Chairman,...
  • REGIONAL EXECUTIVE DIRECTOR NORTHERN ROCKIES, PRAIRIES & PACIFIC REGION
    Founded in 1936, the National Wildlife Federation has grown into America's largest and most trusted grassroots conservation organization with 53 state/territorial affiliates and more than...
  • STEWARDSHIP MANAGER
    STEWARDSHIP MANAGER Job Vacancy and Description Posted June 2, 2021: Open until filled The New Mexico Land Conservancy (NMLC) is a non-profit, regional land trust...
  • KSJD - MORNING EDITION HOST/REPORTER
    KSJD is seeking a host/reporter. Please see for www.ksjd.org for more information. EEO compliant.
  • ON THE EDGE OF CEDAR MESA/BEARS EARS
    Quiet, comfy house for rent in Bluff, Utah. Walk to San Juan River. Bike or hike to many nearby ruins and rock art sites. Beautiful...
  • CARPENTER AND LABORER WANTED.
    Come to Ketchikan and check out the Rain forest on the coast, Hike the shorelines, hug the big trees, watch deer in the muskeg meadows,...
  • PROJECT MANAGER
    Title: Project Manager Reports To: Program Director Salary Range: Negotiable; starting at $60,000 Location: Bend, OR The Deschutes River Conservancy seeks a Project Manager to...
  • PROGRAM DIRECTOR
    The Deschutes River Conservancy seeks a Program Director to join our dynamic team in restoring streamflow and improving water quality in the Deschutes Basin. WHO...
  • EXECUTIVE DIRECTOR - TWISPWORKS
    Established healthy nonprofit in the Methow Valley of Washington state, TwispWorks is hiring the next Executive Director. Terrific opportunity to strive for our mission to...
  • BOARD DIRECTOR
    Help us achieve our mission of promoting excellence in the professional practice of wilderness stewardship, science and education to ensure the life-sustaining benefits of wilderness....
  • TEMPORARY FULL-TIME RANCH OPERATIONS ASSISTANT
    Twin Willows Ranch in Ocate, NM is seeking to immediately fill a Temporary Full-Time employment position as Ranch Operations Assistant for Facilities, Equipment, Land, and...