The Occurrence of Juvenile Corynosoma (Acanthocephala) in Pacific Salmon (Oncorhynchus spp.)

Abstract

Of 2406 Oncorhynchus nerka and O. gorbuscha collected in 1955 and 1956 from many localities throughout their range in the North Pacific and adjacent seas, 1.79% were infected with juvenile Acanthocephala of the genus Corynosoma. In O. nerka the genus was represented by C. strumosum, C. villosum, C. semerme and C. hadweni, all of which use Pinnipedia as the normal definitive hosts. C. strumosum and C. villosum were found in O. gorbuscha. Apparently there are no previous reports of the genus Corynosoma in Oncorhynchus, nor of C. semerme and C. hadweni in any intermediate host in the North Pacific region. O. nerka is the first recorded intermediate host of C. villosum. Data on incidence and intensity of infection of the two hosts by each of the species and the locality and date of catch of the infected salmon are tabulated. Brief descriptions of the four species, based on the collected specimens, are given.