The Steller sea lion (Eumetopius jubatus) population has declined by as much as 70% over the past decade. The incidence of disease in Steller sea lions and, in particular, the role that disease may play in juvenile survival is poorly documented. The Marine Mammal Center, a rehabilitation facility in central California, has admitted 7 neonatal Steller sea lions since 1981. Hematological parameters and pathological findings for these pups are presented in this report.

The four pups which survived to release were in rehabilitation for nine to twelve months. Body weight increased from an average of 20kg at admission to 70kg at release. Hematological and serum biochemical values throughout rehabilitation were similar to those obtained from California sea lion pups of the same age undergoing rehabilitation.

Of the three non-survivors, one female, approximately three months old, died within 5 hours of admission, remaining obtunded with fine motor tremors the entire time. Gross pathology revealed severe emaciation with areas of diffuse redness in the small intestine and focal consolidation of the dorsal lung lobes. The second non-survivor, a one to two month old male, died of severe, necrotizing hepatitis, pleuritis, and interstitial nephritis of unknown origin, after three months of hospitalization. In addition, a one to two month old female died three days after admission of cerebellar herniation. Histopathology revealed medullary and cerebral edema. Clinical pathology findings in these three pups included transient elevated white cell counts of 17-25Xl03, hypoglobulinemia (1.1 - 1.8gm/di), hyperbilirubinemia (1 2.8mg/di or greater), elevated AST (81 OU/I or greater), and anemia. The one consistent finding in all three cases was moderate to severe emaciation.

These results underscore the urgent need for thorough physical examination in conjunction with clinical and microscopic pathology to elucidate all the contributing factors involved in stranding and mortality for Steller sea lions.