Mortality Classification of Stranded Pinnipeds in San Diego County, California: A 5-Year Retrospective of Necropsy Findings
Judy St. Leger; Erika Nilson;Todd Schmitt; Hendrik Nollens; Jody Westberg
Because of their coastal distribution, population health concerns of stranded pinnipeds can provide insight into disease issues in both the ocean and coastal terrestrial environments. While stranded animals may not perfectly reflect the health concerns of the free-ranging population, monitoring the distribution and character of health issues of stranded pinnipeds can provide insight into changing environmental conditions and disease concerns of a population.
A review of necropsy results from pinnipeds that died subsequent to live-stranding events in San Diego County, California from 2005–2009 was performed. All cases were examined within 48 hours of death and the animals were considered to be in good postmortem condition. Species evaluated included California sea lions, harbor seals, Guadalupe fur seals, Northern fur seals, and Northern elephant seals. Necropsy investigations varied from gross examinations to a full investigative panel including histopathology and occasional electron microscopy, microbiology, toxicology, PCR screening for pathogens, screening for biotoxins, and advanced imaging. All findings were tabulated and each case was assigned to an ultimate cause of death category. A total of 773 pinnipeds stranded in San Diego County during the study period. Of these animals, 268 died while in rehabilitation. Classification of cause of death revealed 101 animals died from infectious disease, 50 died from confirmed or suspect domoic acid intoxication, 23 animals died from trauma, 11 died from neoplasia, 29 died from malnutrition, and 26 animals died from other causes of death. Of the examined animals, 28 did not have sufficient history or findings to determine a cause of death.
Beyond the county-based evaluation of stranded pinnipeds, these data were combined with results from stranded cetaceans from San Diego County and submitted to the Marine Mammal Health Map project to expand the regional dataset of health concerns for all marine mammals of Southern California. Future comparisons of animal issues in San Diego as compared to the larger regional dataset may prove illuminating in determining localized health issues in these species.
Special thanks go to the SeaWorld animal care and veterinary laboratory staffs for their indefatigable efforts in the care of the stranded animals. Their efforts make the difference in the lives of individual animals every day.