The American Eel is a widely distributed catadromous fish in North America. Eels generally move long distances upstream from the Atlantic coast inland before spending most of their life in freshwater. Because of their unique life history, eel elvers (‘glass eels’) move marine nutrients inland while adult eels move freshwater nutrients to the marine environment. Preliminary carbon (δ13C) and nitrogen (δ15N) stable isotope analyses of aquatic food webs in Eagle Lake (Acadia National Park, Maine, USA) indicated a marine source of nutrients where passage and connectivity for anadromous fishes was limited. Subsequent elver collections indicate these juvenile fish are a rich source of marine nutrients. Elver collections in Maine indicate that, although depressed from their historical abundance, eels could be a seasonally dominant food resource for fishes in lakes that otherwise appear disconnected from marine environments. In Eagle Lake, for example, mixing models suggest glass eels represent over 40% of the incorporated diet in the spring, coincident with migration of eels upstream. The ability and importance of eels to link marine to freshwater ecosystems through an unassuming life stage, may be underestimated and an important consideration in efforts to restore inland ecosystems.