Current prevalence of adult Uncinaria spp. in northern fur seal (Callorhinus ursinus) and California sea lion (Zalophus californianus) pups on San Miguel Island, California, with notes on the biology of these hookworms

A prevalence survey for hookworms (Uncinaria spp.) was done in northern fur seal (Callorhinus ursinus) and California sea lion (Zalophus californianus ) pups on San Miguel Island, CA, in 2000. Intestines of dead pups were exam ined for adult hookworms in July. These parasites were found in 95% of 20 f ur seal pups and 100% of 31 sea lion pups. The number of hookworms varied f rom 4 to 2142 ((x) over bar = 760) in fur seal pups and from 20 to 2634 ((x ) over bar = 612) in sea lion pups. A direct relationship was evident betwe en body condition and number of hookworms in the pups; that is, pups in poo r condition had fewer hookworms than those in good condition, There was a d ecline in the number of hookworms in sea lion pups in 2000 compared to coll ections in 1994. Eggs of Uncinaria spp. were found in rectal feces (collect ed in late September and early October) of none of 35 (0%) live fur seal pu ps and 41 of 48 (85%) live sea lion pups, Packed cell volume values, determ ined for most of the same live pups, were essentially normal for C. ursinus but were much lower than normal for most Z. californianus. Hookworm larvae were not found in blubber of fur seal and sea lion pups or in rookery sand in July, Rookery sand, positive for Live hookworm larvae when put in a ref rigerator, was negative at removal 2.5 years later The average number of eg gs in utero of female hookworms was 285 for three specimens from a fur seal pup and 281 from three specimens from a sea lion pup. One hookworm larva w as recovered from milk stripped from the teats of a stranded Z. californian us female at The Marine Mammal Center, Sausalito, CA. (C) 2001 Published by Elsevier Science B.V.