Limnotrachelobdella okae (Hirudinida, Piscicolidae) from Cherry Salmon Oncorhynchus masou masou in Neritic Deep Waters of the Western North Pacific Ocean

The piscicolid leech Limnotrachelobdella okae (Moore, 1924) was found attached to the skin near the pectoral fin of a cherry salmon Oncorhynchus masou masou caught at a depth of 180-200 m in the western North Pacific Ocean off the east coast of northern Honshu, Japan. This is the first record of L. okae from the ocean-swimming salmonid in neritic deep waters although it is not known where the fish was infected. L. okae has been generally believed to be a parasite of both marine and freshwater fishes, but it is concluded, based on the present results and the literature review on the host and distributional records, that the leech is a coastal marine or brackish-water species: the infection occurs only in salt waters, and anadromous fishes, such as salmonids, carry the leech to fresh waters, where it can survive for a certain period