Contracaecum spp. from endemic Baikal fishes: the Baikal yellowfin Cottocomephorus grewingkii (Dybowski, 1874) and the longfin Baikal sculpin Cottocomephorus inermis (Yakovlev, 1890)

All the nematodes found in body cavities of the examined endemic Baikal fishes: 88 Baikal yellowfin Cottocomephorus grewingkii (Dybowski, 1874) and 35 longfin Baikal sculpin Cottocomephorus inermis (Yakovlev, 1890) were identified as Contracaecum osculatum baicalensis (Mozgovoi and Ryjikov, 1950) L3 larvae. The prevalence, mean intensity, intensity range and abundance of the nematodes in C. grewingkii were 37.5%, 2.55, 1-31, and 0.96, respectively, the corresponding values in C. inermis were 60.0%, 2.43, 1-10, and 1.46. The infestation level in C. grewingkii was significantly higher than in C. inermis (Mann-Whitney U-test, p<0.02). The number of parasites was found to increase with the fish length. Although in both and C. inermis, the anisakids were more frequent in males (prevalence of 52.17 and 67.76%, respectively) than in females (prevalence of 35.39 and 42.86%, respectively), differences between the sexes in the infestation level in the two species were not significant (Mann-Whitney U-test, P= 0.09 and P=0.23, respectively). The molecular method applied (PCF-RFLP) allows to identify all the nematodes in both examined fish species as C. osculatum baicalensis.