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
  • CANYONLANDS FIELD INSTITUTE
    Colorado Plateau Natural & Human History Field Seminars. Lodge, river, hiking options. Small groups, guest experts.
  • NATURE EDUCATION DIRECTOR
    Our mission is to inspire a life-long connection to nature and community through creative exploration of the outdoors. We are seeking an educational leader who...
  • DEVELOPMENT AND MARKETING DIRECTOR
    The Development and Marketing Director is a senior position responsible for the execution of all development and marketing strategies to raise funds and increase public...
  • DEVELOPMENT COORDINATOR
    Coordinates all Wyoming Wildlife Federation philanthropic activities. Tasks include identification, recruitment, and retention of donors, organizing fundraising events, and assisting with grant writing.
  • REALTOR NEEDS A REMOTE ASSISTANT
    This is a business assistant position, The working hours are flexible and you can chose to work from anywhere of your choice, the pay is...
  • CORPORATE & GRANTS PARTNER MANAGER
    Forever Our Rivers Foundation Corporate Partnerships Manager February 2020 www.ForeverOurRivers.org Forever Our Rivers Foundation, a 501(c)(3) nonprofit, was formed in late 2016 with the mission...
  • EXECUTIVE DIRECTOR
    Central Oregon LandWatch is seeking an Executive Director to advance our mission and oversee the development of the organization. Job Description: The Executive Director oversees...
  • WESTERN NATIVE SEED
    Specializing in native seeds and seed mixes for western states.
  • MEDIA DIRECTOR
    Love working with the media? Shine a spotlight on passionate, bold activists fighting for wild lands, endangered species, wild rivers and protecting the climate.
  • STAFF ATTORNEY - NEVADA
    The Center for Biological Diversity is seeking an attorney to expand our litigation portfolio in Nevada. Come join our hard-hitting team as we fight for...
  • EXECUTIVE DIRECTOR
    The Montana Wildlife Federation seeks an energetic leader to advance our mission, sustain our operations, and grow our grassroots power. For a full position description,...
  • HISTORIC COMMERCIAL OPPORTUNITY IN DOWNTOWN NOGALES
    Nogales. 3 active lower spaces and upper floor with lots of potential. 520-245-9000 [email protected]
  • CHUCK BURR'S CULTUREQUAKE.COM BLOG
    Change will happen when we see a new way of living. Thinking to save the world.
  • COMING TO TUCSON?
    Popular vacation house, furnished, 2 bed/1 bath, yard, dog-friendly. Lee at [email protected] or 520-791-9246.
  • DIRECTOR, TEXAS WATER PROGRAMS
    The National Wildlife Federation seeks a Director to lead our water-related policy and program work in Texas, with a primary focus on NWF's signature Texas...
  • SPLIT CREEK RANCH
    Spectacular country home on 48 acres with Wallowa River running through it! 541-398-1148 www.RubyPeakRealty.com
  • OJO CALIENTE COMMERCIAL VENTURE
    Outstanding location near the world famous Ojo Caliente Mineral Spring Resort. Classic adobe Mercantile complete w/living quarters, separate 6 unit B&B, metal building and spacious...
  • NEW MEXICO GILA NATIONAL FOREST HORSE RANCH
    43 acres in the Gila National Forest. Horse facility, custom home. Year-round outdoor living. REDUCED to $999,000, 575-536-3109.
  • EVERLAND MOUNTAIN RETREAT
    Everland Mountain Retreat includes 318 mountaintop acres with a 3,200 square foot lodge and two smaller homes. Endless vistas of the Appalachian mountains, open skies,...
  • COPPER CANYON MEXICO CAMPING & BACKPACKING
    Camping, hiking, backpacking, R2R2R, Tarahumara Easter, Mushroom Festival, www.coppercanyontrails.org.