Abstract
Five species of helminth endoparasite (two digeneans, Brachyphallus crenatus (Rudolphi, 1802) and Lecithaster gibbosus (Rudolphi, 1802); two cestodes, plerocercoids of Nybelinia surmenicola (Okada in Dollfus, 1929) and a tetraphyllidean; and an acanthocephalan, post-cystacanths of Bolbosoma sp.) were found in adults of Arctic lampreys Lethenteron camtschaticum (Tilesius, 1811) arriving in the lower part of the middle reaches of a river in Hokkaido, Japan, for spawning after a period of growth in the sea. These parasites are all common species previously reported from various marine fishes in the North Pacific and all have complex life-cycles involving host-to-host transmission via a predator-prey relationship. To have become infected with these food-borne parasites, Arctic lampreys need to have ingested various body parts of infected prey fishes at sea. Consequently, the endoparasites recovered suggest that the Arctic lamprey has a role as a predator in marine ecosystems.
