COS 171-2 - Understanding Chinook salmon-ecosystem interactions at the limit of their inland range, as told by trees and Teslin Tlingit Knowledge Holders
Professor University of Calgary Calgary, Alberta, Canada
Background/Question/Methods
Pacific salmon (Oncorhynchus spp.) function as major sources of sustenance and nutrients in moving from marine environments inland. This has been demonstrated in coastal systems by positive relationships between Pacific salmon abundance and riparian tree growth and δ15N, likely mediated by predators and scavengers fertilizing the soil through consuming and transporting salmon carcasses. This study investigated whether these relationships occur at the limit of Chinook salmon distribution on the Teslin Tlingit Council (TTC) Traditional Territory in Southern Yukon. Tree growth chronologies were created at five riparian sites for 40-50 trees (N = 220) and related to salmon escapement or abundance data from the Yukon and Teslin rivers. Interviews were conducted with three Teslin Tlingit knowledge holders to study salmon-ecosystem interactions on the Traditional Territory.
Results/Conclusions
Site growth chronologies were significantly and positively related to salmon escapement at three of four salmon-bearing sites and not at the negative (salmon-free) control site. Mean annual growth was higher at all salmon-bearing sites with significant salmon-growth relationships than at the negative control site. Salmon were estimated to increase tree growth by 17-39%. Mean δ15N was significantly higher at salmon-bearing sites compared to the negative control. Interviews revealed measures of a healthy salmon run and large population declines that have negatively impacted local ecosystems (namely bears) and human wellbeing. Western scientific methods and Indigenous Knowledge included in this study suggest salmon population declines in the area have likely altered their role as nutrient sources. This study demonstrates the ubiquity of salmon as ecological and cultural keystone species, and the importance of considering multiple ways of knowing to improve research in complex ecological (and social-ecological) systems.
