Blue Highways: The Migration Ecology of Atlantic Salmon from Maine Estuaries to the Scotian Shelf

Gulf of Maine Atlantic salmon are endangered and historically low marine survival is a primary factor limiting recovery. Scientists first documented the importance of riverine migratory corridors, and then tagging/return-rate analyses quantified overall marine survival and general marine habitats.   Now, marine telemetry is allowing us to understand migratory corridors in expansive estuarine, coastal, and shelf ecosystems.  Using Penobscot Bay, Gulf of Maine, and Halifax Line tracking networks, we examined migrations of over 125 Penobscot River postsmolts from 2005-2012.  We follow these fish progressively from 1) general migration in coastal systems, 2) routes around islands and channels, to 3) transit along their 1,000 km trek to the Scotian Shelf. As society’s demands to develop marine ecosystems increase, it becomes more important to understand and map ocean habitats.  Early results from marine telemetry suggest rapid offshore movements along what appear to be somewhat narrow migration corridors.  We are moving beyond the concept of marine survival as a large black box towards a new paradigm of marine salmon habitat as a complex and dynamic network of blue highways. We hypothesize that working cooperatively with oceanographers this network can be mapped and understood, aiding the study and conservation of salmon at sea.