T.R. Spraker; D. Calkins; D.J. Bradley; T. Loughlin
Merrick, R. Department of Pathology, College of Veterinary Medicine,
Colorado State University, Fort Collins, CO; Alaska Department of Fish and Game, Anchorage,
AK; Wildlife Pathology International, Fort Collins, CO; National Marine Mammal Laboratory,
NOAA, Seattle, WA
For the last seven years investigations of the causes of diseases of
free-ranging Steller Sea Lions have been done. Methods of investigation have been necropsy
of animals that were either found dead or collected. Procedures performed on animals
included gross necropsy, histopathology, bacteriology and serology, A subacute ulcerative
dermatitis with alopecia, acanthosis and keratosis believed to be due to calicivirus and
lice was found in pups. A chronic active dermatitis due to an unidentified mycotic agent was
common. A mild multifocal pneumonia associated with lungworms and secondary bacterial
infection was common. Mild mucopurulent rhinitis associated with nasal mites was extremely
common. Gastric ulceration due to ascarids and gastric foreign bodies was a common
incidental finding. Acanthocephalans and cestodes were found in the small intestine and
caecum. Positive serological titers to chlamydia were found. A chlamydial organism was
isolated from an aborted fetus from Cape St. Elias, Alaska. Emaciation was found in two 8-1
0 month old animals. A mild degree of neuronal degeneration was found in the brain stem of
two adults. Gun shot was found in two adults.
A variety of diseases and infectious agents were found but none appeared
to be related with the general decline. Abortion may be a significant factor in the decline
of Steller populations. The causative agents of abortion have not been determined.