Meeting Abstract
Extreme body elongation is often linked with the ability to move between aquatic and terrestrial habitats. Fish are known to move onto land to escape poor water conditions, for better breeding sites, or other high quality resources. One highly elongate species known to traverse terrestrial environments is the American eel (Anguilla rostrata). American eels have a unique life cycle during which eggs are laid in the Sargasso Sea and leptocephalus larvae are transported along the coast. Glass eels then move into freshwater systems and mature into yellow eels which may spend decades in freshwater prior to becoming sexually mature (silver eels) and returning to the Sargasso Sea to reproduce. Along the east coast of the United States, many of the rivers from where American eels may migrate are blocked by dams. Despite this anthropogenic barrier, eels are found upstream of dams. Previous work has shown that glass eels can climb the vertical sides of a dam, but this behavior has not been described in older eels. In this study, we expand our understanding of eel terrestrial locomotion by examining eels moving along sand, loose pebbles, and fixed pebble substrate) and 4 inclines ranging from 0 to 15 degrees. Eels were resistant to climbing the higher inclines and often moved into a concertina-like locomotion in comparison to the undulatory locomotion they often used at lower angles. Distance ratio, a measure of the effectiveness of movement, was lower at higher inclines indicating more lateral movement of the body. These experiments reveal that steep inclines 15+ degrees impose additional effort on locomotion for this commercially important fish. By understanding these constraints, we can help develop management strategies to mitigate the increased energetics imposed by dams.
