Studying Chinook salmon in northern river ecosystems through ecological methods and Indigenous, Teslin Tlingit knowledge

In this study, we examined Pacific salmon decline and ecosystem function through Western science and Indigenous, Teslin Tlingit knowledge. We tested relationships of riparian tree growth and nitrogen composition at the limit of Pacific salmon distribution on the Teslin Tlingit Council (TTC) Traditional Territory in Southern Yukon, studied ecosystem roles of salmon and population declines in the area, and the interactions of these processes. Within sites, tree growth was positively related to salmon escapement at all salmon-bearing sites and not at the negative (salmon-free) control site. Mean δ15N was significantly higher at salmon-bearing sites compared to the negative control, showing similar patterns to comparable studies. Between sites, mean site tree growth did not show a clear response to salmon. Interviews conducted with Teslin Tlingit knowledge holders revealed measures of a healthy salmon run and large population declines that have negatively impacted local ecosystems (particularly bears, key to delivering salmon nutrients to terrestrial ecosystems) and human wellbeing on the Traditional Territory. Although this study was limited by available sites and data, we demonstrate that the health of salmon and riparian forests on the Traditional Territory are deeply linked, and the importance of considering multiple ways of knowing to improve ecological research.