For 20 years, Tom Quinn, a professor in Aquatic and Fishery Sciences at the University of Washington, waded in southwestern Alaska’s Hansen Creek with his students, counting and measuring sockeye salmon carcasses in the stream. Quinn asked his students to toss the bodies on the north bank of the creek to avoid double counting; over the years, they tossed close to 295 tons of salmon onto the north bank. In 2016, Quinn and his colleagues and students took core samples from the white spruce growing on both sides of the creek. The samples revealed that over the course of the study the salmon-fertilized trees on the north bank had caught up in growth with the taller trees on the south side (which had more sunlight exposure). Nutrients from the salmon bodies had leached into the soil or made their way into it via defecation or urination by bears, eagles, or other wildlife. In addition to demonstrating how the nutrients in salmon can aid tree growth, says Quinn, the study shows the importance of these fish for an entire ecosystem. “Many of our streams have far fewer salmon than we used to have. Some of those ecosystem benefits have been lost. So when we go to Alaska and do these studies, it reminds us down here that these things matter.” LOV

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Photo: 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 of Hansen Creek in southwest Alaska.
 

Incidental findings of a long-term study of brown bear predation on salmon have revealed a hidden link between the fish and forest health. For 20 years, Tom Quinn, a professor in Aquatic and Fishery Sciences at the University of Washington, waded in southwestern Alaska’s Hansen Creek with his students, counting and measuring sockeye salmon carcasses in the stream. Quinn asked his students to toss the bodies on the north bank of the creek to avoid double counting; over the years, they tossed close to 295 tons of salmon onto the north bank. In 2016, Quinn and his colleagues and students took core samples from the white spruce growing on both sides of the creek. The samples revealed that over the course of the study the salmon-fertilized trees on the north bank had caught up in growth with the taller trees on the south side (which had more sunlight exposure). Nutrients from the salmon bodies had leached into the soil or made their way into it via defecation or urination by bears, eagles, or other wildlife. In addition to demonstrating how the nutrients in salmon can aid tree growth, says Quinn, the study shows the importance of these fish for an entire ecosystem. “Many of our streams have far fewer salmon than we used to have. Some of those ecosystem benefits have been lost. So when we go to Alaska and do these studies, it reminds us down here that these things matter.” LOV

About the author

Lisa Owens Viani is a freelance writer and editor specializing in environmental, science, land use, and design topics. She writes for several national magazines including Landscape Architecture Magazine, ICON and Architecture, and has written for Estuary for many years. She is the co-founder of the nonprofit Raptors Are The Solution, www.raptorsarethesolution.org, which educates people about the role of birds of prey in the ecosystem and how rodenticides in the food web are affecting them.