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A long time experiment demonstrates the iconic fish help trees grow.
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Andrea Odell, an undergraduate student in the UW School of Aquatic and Fishery Sciences, tosses dead sockeye salmon on the bank of Hansen Creek in southwest Alaska.
Dan DiNicola / University of Washington
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Both live salmon sockeye and fish carcasses are seen in Hansen Creek in 2014.
Tom Quinn / University of Washington
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Alex Lincoln, a graduate student in the UW School of Aquatic and Fishery Sciences, carries fish 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
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Sam May, a graduate student in the UW School of Aquatic and Fishery Sciences, measures sockeye salmon carcasses.
Dan DiNicola / University of Washington
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Salmon sockeye tag researchers.
Dennis Wise / University of Washington
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UW researchers walk along Hansen Creek in southwest Alaska this August.
Dan DiNicola / University of Washington
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Kyla Bivens, an undergraduate student in the UW School of Aquatic and Fishery Sciences, uses a deadly sockeye salmon on the bank.
Dan DiNicola / University of Washington
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Sarah Schooler, a UW undergraduate student at the time, and Martini Arostegui, a UW PhD student in the School of Aquatic and Fishery Sciences, at the mouth of Hansen Creek in 2015.
Dennis Wise / University of Washington
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Tom Quinn, Sarah Schooler, and Arostegui Martini, walk along Hansen Creek in southwest Alaska in 2015.
Dennis Wise / University of Washington
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Blakeley Adkins snips spruce needles along Hansen Creek for the study's chemical analysis.
Catherine Austin / University of Washington
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Researchers measure trees along the creek.
Catherine Austin / University of Washington
Every year of salmon sockeye meets their end in Hansen Creek, a tributary of Lake Aleknagik in southwestern Alaska, whether or not they are old enough. Either way, they're pretty much down to the side 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 are about 295 tons of salmon on 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 to 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 salmon nutrients bring their way to the ocean in the woods and trees. But this experiment, described in a paper by Tom Quinn, a professor in the School of Aquatic and Fishery Sciences at the University of Washington, proves a more basic fact.
Quinn, who has been teaching and researching in southwestern Alaska since the late 1980s, being studied in the relationship between bear predation and salmon populations. Over the years, his work and the work of his collaborators and students to 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 the lead from Hansen's spindly Creek. "In the back of my mind I've been thinking about the fertilization impact," Quinn said. It seemed like the right time to see what the effect was: "I'm not going to be doing this forever. Twenty years ago seemed like a good time to analyze the data. "The core samples revealed that the fertilized trees had grown faster than the previous years. 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 water and water between different streams, Quinn said. And in doing so, they are not able to other causes: Water availability, elevation, and other factors impacting soil fertility. Quinn's somewhat accidental experiment removed many of these factors.
The research strengthened 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. Follow @ carlschirps
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