Date of this Version
A breeding population of approximately 8,000–10,000 northern fur seals (Callorhinus ursinus) is located at San Miguel Island in the California Channel Islands. The population is increasing and produces about 2,500 pups annually (Melin et al. 2008). Pup mortality has increased during the past 10 yr and has reached 50% or more in some recent years. Although we have not completed studies to describe the causes of this pup mortality, it appears that hookworm disease has been a major cause (Lyons et al. 2001).