Anguillicoloides crassus : an invasive parasitic nematode infecting American eel (Anguilla rostrata) in Cape Breton, Nova Scotia

Abstract

In 2007, Anguillicoloides crassus, an invasive, parasitic nematode found in the swimbladder of anguillid eels was documented for the first time in American eel in Canadian waters, including two sites in Cape Breton (CB) Island, Nova Scotia. That discovery necessitated this study on the distribution, ecology and origin of the parasite. It was found that sites throughout CB contain infected eels. Comparing the COI gene of the mitochondrial DNA among nematodes from CB, USA, Europe, and published sequences, it was determined that the CB infection likely originated from a direct transmission of the parasite from the USA or Japan via natural eel, intermediate or paratenic host movement and/or within the ballast water of boats. Infection occurred in both freshwater and estuarine sites, with intensity of infection increasing with length of eel. Pathological damage to the swimbladder was evident; however condition factor, liver somatic and spleen somatic indices were not affected by infection.