A Study of Uncinariasis in Northern Fur Seal Pups, Callorhinus ursinus, on the Rookeries of Bering Island, 2011–2012

Carcasses of northern fur seal pups, Callorhinus ursinus, collected from the rookeries of Bering Island (n = 133), were examined for hookworms Uncinaria spp. The parasite was found in 90% of the pups from the Severo-Zapadnoe rookery and in 45% of the pups from the Severnoe rookery. This difference in prevalence of nematode infection between the rookeries is associated with the type of substrate, as well as with the pattern of distribution of the seal reproductive groups on each of the rookeries.