Passage of adult Atlantic salmon in the Penobscot River, Maine

Atlantic salmon runs in the Penobscot and Kennebec Rivers of Maine are federally endangered and remain low. Inefficient fishways at dams continue to slow and prevent upstream migrations to spawning habitat, and delays of weeks to months are common. These delays expose fish to elevated water temperatures, resulting in increased metabolic demands. These energetic costs have not been quantified, nor have fitness outcomes been characterized, but energy loss may affect gonadal development, spawning performance, and probability of surviving to spawn again. Consequently, the goal of this research is to characterize specific energetic costs of the delays to upstream migrating adult salmon using bioenergetics modeling. Understanding tradeoffs in overall fitness with respect to migration delays could inform development of dam passage criteria standards. This project is a collaboration between NOAA and the Maine Department of Marine Resources.