Coho salmon are iconic anadromous fish facing population declines from habitat loss, fishing pressure, and climate change. Stream restoration directly improves welfare conditions for wild coho.
Wild coho salmon welfare is primarily determined by stream habitat quality. During freshwater rearing, thermal stress from elevated summer stream temperatures — caused by riparian deforestation and climate change — causes physiological stress and mortality. Low summer flows concentrate fish in smaller areas with reduced oxygen and increased predation risk. Stream restoration through large woody debris placement, riparian planting, and road decommissioning improves both habitat quality and individual fish welfare by restoring the thermal refugia, cover, and pool habitat that coho require. Hatchery supplementation raises welfare concerns about overcrowding in artificial facilities, transportation stress, and the genetic and behavioral impacts on wild fish they interact with after release.