American Eel Passage in a Coastal Watershed: Is Eel Ladder Use Size Dependent?

The American eel (Anguilla rostrata) is a catadromous species that spawns in the Sargasso Sea and migrates upstream to live in rivers along the Atlantic Coast from northern Venezuela to Greenland.  Within the United States portion of its range, American eel populations are declining.  While the exact cause of the decline is unknown, loss of nursery habitat due to dam construction is believed to be a large contributing factor.  As a result, some dams are being retrofitted with eel ladders in order to facilitate upstream migration.  It is the goal of this study to determine ladder use by size, age class, and gender by comparison with downstream demographics.  We have found that the year classes of eels differed between the spring and summer migration runs, and that the run demographics are similar to those found immediately downstream of the dam.