A survey of parasites of the American lobster, Homarus americanus (Crustacea: Decapoda), from the Canadian Maritimes

Examination of 885 lobsters (Homarus americanus) trapped in five areas of the Canadian Maritimes during 1980–1982 revealed four parasite species: Porospora gigantea (Apicomplexa: Sporozoea), Polymorphus botulus (Acanthocephala: Palaeacanthocephala), Hysterothylacium sp. (Nematoda: Secernentea), and Stichocotyle nephropis (Platyhelminthes: Trematoda). The prevalence and abundance of each parasite species did not differ significantly (p > 0.05) between lobster sexes or size groups. Lobsters in each area were characterized by a high prevalence of P. gigantea (43.6 to 84.2%) and low prevalences of P. botulus (1.3 to 9.9%) and Hysterothylacium sp. (1.1 to 5.6%). Stichocotyle nephropis was found in one lobster from German Bank. The parasite fauna were similar throughout the areas sampled, which suggests that the data were of little value for lobster stock discrimination. However, lobsters probably acquired P. botulus in the shallow coastal areas where the primary hosts of this parasite occur; therefore, the presence of P. botulus in lobsters from inshore and offshore areas south and southeast of Nova Scotia suggests some mixing between coastal lobsters and those on the continental shelf.