Ecology of Herpesvirus Infection and Cancer in Sea Lions

University Of California-Davis, Davis CA

Investigators

Abstract

California sea lions (CSL) have an unusually high incidence of cancers, the most frequent of which are aggressive urogenital tumors in both males and females. The foraging biology of CSL, which differs between age and gender classes, brings them into contact with pollutants that accumulated in their tissues. Some of these are known to cause cancer. However, more than one factor is needed to cause cancer and a CSL herpesvirus has been identified that may also contribute. Intrinsic factors (age, gender, genetic makeup), environmentally acquired factors (tissue contaminants, other infectious agents), as well as population natural history factors (feeding behavior and foraging ranges) are expected to influence the susceptibility of CSL to herpesvirus infection and cancer. Animals captured and released on California breeding grounds and in Puget sound and stranded animals in rehabilitation centers will be tested for antibodies, viruses, bacteria, genetic markers, blubber contaminant levels and comparisons made between age classes, genders and CSL with and without tumors. Satellite telemetry will be used to track juvenile females and to resample individual CSL. A model will be developed to assess factors important in the ecology of herpesvirus infections and cancer. California sea lions live and feed in the Pacific coastal ecosystem in which people work and recreate, eating many of the same seafood. They are important sentinels for ecosystem health. The high incidence of cancers in sea lions is alarming. Understanding factors causing these cancers will help assess risks to human health as well as to other coastal wildlife including threatened Steller's sea lions, Guadalupe fur seals and southern sea otters.