Distribution, prevalence, and intensity of the swim bladder parasite Anguillicola crassus in New England and eastern Canada

In the summer of 2005, yellow phase American eels Anguilla rostrata were examined for the swim bladder parasite Anguillicola crassus from 26 locations in New England, USA, ranging from the Pawcatuck River, Rhode Island, to the East Machias River, Maine. An additional 12 sites were sampled within Canada during the summers of 2006 and 2007: 7 sites in southern Nova Scotia and 5 sites within the St. Lawrence River system. In 2007, eels were also obtained from New Brunswick, northern Nova Scotia, Prince Edward Island, and Newfoundland through the commercial eel fishery. All locations in Rhode Island (n = 3) and Massachusetts (n = 10) and 7 in Maine (n = 13) had infected eels, with parasite prevalence ranging from 7 to 76%. No eels sampled from southern Nova Scotia or the St. Lawrence River system were infected with the parasite. New Brunswick and northern Nova Scotia had infected eels ranging from 3 to 30% parasite prevalence, with Cape Breton, Nova Scotia, being the furthest north the parasite has been reported in American eels. There was no significant relationship between parasite prevalence and latitude. The present study supports the hypothesis that the parasite is capable of expanding its range further into the Maritimes and could potentially reach the St. Lawrence River system.