A Systematic Approach to Improve Passage at Dams Necessary for Recovery of Endangered Atlantic Salmon

Atlantic salmon in Maine are in danger of extinction.  Dams are a major threat to Atlantic salmon recovery because they limit access to historic spawning and rearing habitat, they directly kill and injure a significant number of salmon on both upstream and downstream migrations, and they also degrade the productive capacity of habitats upstream by inundating formerly free-flowing rivers, reducing water quality, and changing fish communities.  Of the 713,000 units (1habitat unit = 100m²) of historically accessible spawning and rearing habitat, dams impair access to 212,000 units and preclude access to 414,000 units leaving 87,000 units of habitat fully accessible to Atlantic salmon.   Of the 87,000 units that are fully accessible, 48,000 units of habitat are considered marginal for supporting Atlantic salmon spawning and juvenile rearing.   Recovery goals, habitat quality scores and habitat quantity scores used in identifying critical habitat (pursuant to the Endangered Species Act) have provided us with the resources to plan for, and direct connectivity projects for Atlantic salmon.   One of the Atlantic salmon recovery goals is to achieve 90,000 units of fully accessible medium to high quality habitats.  To achieve this goal, a we have devised a five prong strategic approach for improving access to important habitats blocked by dams:  all dams are being scored based on their relative conservation value to Atlantic salmon if the dam were removed or fish passage improved; all owners of the 467 dams that preclude or impair access to Atlantic salmon habitat are being identified and contacted to ask if they would consider dam removal or fish passage improvements; dam specific passage efficiency goals for all federally regulated dams are being developed;  a General Conservation Plan for all non-federally regulated dams that provide incentives for dam removal is being developed; and a rigorous monitoring program is being implemented to test the underlying assumptions of the putative effects of dam removal.