Review of metazoan parasites of the northern fur seal (Callorhinus ursinus) and the analysis of the gastrointestinal helminth community of the population on St. Paul Island, Alaska

The northern fur seal (NFS), Callorhinus ursinus (Mammalia: Otariidae), is a marine mammal species included into the IUCNRed List as the vulnerable species which population is dramatically declining. A significant amount of parasitological datacollected previously and our recent data allowed us to clarify the list of NFS metazoan parasites and to perform a comprehensiveanalysis of the gastrointestinal helminth community. Gastrointestinal tracts from 756 NFSs (3- to 4-year-old males) werecollected during the annual Aleut subsistence harvests in July–August of 2011–2014 from five separate rookeries on St. PaulIsland, Alaska. Totally, 27,625 specimens of helminths and approximately 1000 nasal mites were collected and identified.Detailed analysis of the previously published and newly obtained data revealed 32 species of metazoan parasites, includingtrematodes (6 species), cestodes (4), nematodes (9), acanthocephalans (9) and arthropods (4). The gastrointestinal helminthcommunity of newly studied NFSs comprised 19 species including trematodes (4), cestodes (3), nematodes (5) and acantho-cephalans (7). Temporal changes in the helminth community structure were small but statistically significant. Gastrointestinalhelminth infracommunities comprised from 1 to 10 species (average of 4). Small but significant correlation was found betweenthe abundances of acanthocephalans (Corynosoma similis and C. strumosum), nematodes (Contracaecum osculatum,Pseudoterranova spp.) and cestode Diphyllobothrium tetrapterum