Parasites of American shad, Alosa sapidissima (Osteichthyes: Clupeidae), from rivers of the North American Atlantic coast and the Bay of Fundy, Canada

Abstract

Parasites belonging to a total of 26 taxa were recovered from 695 American shad (Alosa sapidissima) sampled from six rivers and one marine location (Cumberland Basin, Bay of Fundy) on the east coast of North America. Of these, 23 taxa are reported from American shad for the first time. Species identified were predominantly boreal marine forms that have low host specificities and widespread distributions. Two species, Hysterothylacium aduncum and Scolex pleuronectis, were found in American shad from all localities (> 60% prevalence). Relative abundance and diversity indices of the parasite assemblages varied in relation to geographic location and temporally in Cumberland Basin. These data suggest that there is different timing of arrival and departure of shad from individual river populations in Cumberland Basin. High levels of prevalence and incidence of exotic, southern parasite species, such as Genitocotyle atlantica, in shad from Cumberland Basin and most or all river populations indicate that all individual shad spend some portion of their life at or near the southern extent of their reported range.