Rediscovery in Japan and host association of Salmincola carpionis (Copepoda: Lernaeopodidae), a parasite of wild and reared freshwater salmonids

Abstract

The parasitic copepod Salmincola carpionis (Krøyer, 1837) was rediscovered in Japan, where this parasite occurred on species of the genus Salvelinus (whitespotted char, S. leucomaenis; brook trout, S. fontinalis; their natural hybrid; Dolly Varden, S. malma; Miyabe char, S. malma miyabei) and rarely on rainbow trout (Oncorhynchus mykiss). The copepods were found on salmonids from a river in central Honshu and on those reared at an aquarium and a fisheries experimental station in northern Honshu. The preferred attachment site was the buccal cavity but at high intensities copepods were a little more frequently found on other parts. Prevalence and mean intensity of infection increased with increased size and age of the fish. At a constant water temperature, there were no seasonal changes in prevalence or mean intensity of infection, which may have resulted from continuous egg production by the copepods. The copepods that were previously described as Salmincola faleulata (Wilson, 1908) and later identified as S. californiensis (Dana, 1852) from kokanee (O. nerka) from Hokkaido, Japan, are assigned to S. carpionis.