Historic logging contributes to water temperature increases for salmon

Juvenile coho salmon. Photo credit: Dylan Cunningham A collaborative study between researchers at Simon Fraser University and Fisheries and Oceans Canada (DFO) has found that high logging intensity in the Interior watersheds of British Columbia is associated with warmer stream temperatures in salmon-bearing streams, potentially contributing to increased heat stress in salmon. Researchers examined forestry activities, watershed characteristics, and stream habitat in the watersheds of 28 tributaries of the North Thompson River to understand how forestry influences salmon habitat in streams. They found that while stream slope explained most of the variation in physical stream habitat, the intensity of logging in a watershed accounted for higher summer stream temperatures. The relationship between logging and stream temperatures was even stronger when the researchers looked at logging within the riparian area, the stretch of trees and vegetation that buffers streambanks and shades streams from sunlight. Their findings are published in the Canadian Journal of Fisheries and Aquatic Sciences. High stream temperatures have a negative impact on salmon.