Estuarine Community and Emigration Ecology of Atlantic Salmon in the Penobscot Estuary, Maine

Acoustic telemetry is a valuable tool for understanding the Atlantic salmon emigration ecology in rivers and estuaries of Maine and Canada.  Many of these populations are endangered or at historic low abundance and marine survival is at historic lows.  Our work is designed to better understand the early stages of marine survival – and smolt ecology.  Our work in the Penobscot River’s Estuary and Bay since 2005 compares near shore migration performance and survival of smolts from different rearing origins and stocking locations to the Gulf of Maine.  These studies have demonstrated differences among migration times, speed, tidal and diel use patterns as well as preferred path choice of tagged smolt groups.  More recently, we have combined our telemetry results and estuary survey data to further our knowledge of the ecosystem and how it relates to salmon survival.  High smolt mortality in the upper estuary (10-25%) and bay entry (15-35%) may be influenced by the co-occurrence, abundance, and size composition of resident and migratory species.   Direct observation of such interactions and the overlap of predators and prey will help to better understand behavior and emigration, and ultimately the survival of Atlantic salmon smolts in the Penobscot estuary.