Prevalence of hookworms (Uncinaria lucasi Stiles) in northern fur seal (Callorhinus ursinus Linnaeus) pups on St. Paul Island, Alaska, USA: 1986-1999

Prevalence of hookworms (Uncinaria lucasi) was studied in northern fur seal (Callorhinus ursinus) pups at necropsy on St. Paul Island, Alaska, U.S.A. Gross examination of 2,121 pups during the period 1986-1998 revealed that o nly 13 had a light hookworm infection and 2 other pups had hookworm disease (moderate hookworm infection, enteritis, and anemia). Specific parasitolog ic inspections of 230 pups in 1988 and 1996-1999 included examinations of f eces for eggs or intestines for adult worms. Hookworm eggs were present in fecal samples of 1 (2%) of 48 pups in 1988 and none of 19 pups in 1996. Spe cimens of II. lucasi, found mostly during qualitative examinations, were in the intestines of 4 (5%) of 77 pups in 1997, 4 (9%) of 47 in 1998, and 1 ( 3%) of 39 in 1999. The 9 infected pups harbored 1-8 hookworms each. Observa tions in this study indicate a dramatic decline in hookworm prevalence in C . ursinus pups on St. Paul Island compared with that of several years previ ously.