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Clinical signs and mortality of non-released stranded California sea lions housed in display facilities: the suspected role of prior exposure to algal toxins
  1. Claire Simeone1,2,
  2. Deborah Fauquier2,
  3. Jennifer Skidmore2,
  4. Peter Cook3,
  5. Kathleen Colegrove4,
  6. Frances Gulland1,5,
  7. Sophie Dennison6 and
  8. Teresa K Rowles2
  1. 1 The Marine Mammal Center, Sausalito, California, USA
  2. 2 Office of Protected Resources, National Marine Fisheries Service, Silver Spring, Maryland, USA
  3. 3 New College of Florida, Sarasota, Florida, USA
  4. 4 Zoological Pathology Program, University of Illinois at Urbana-Champaign College of Veterinary Medicine, Urbana, Illinois, USA
  5. 5 Wildlife Health Center, University of California–Davis, Davis, California, USA
  6. 6 TeleVet Imaging Solutions, PLLC, Oakton, Virginia, USA
  1. Correspondence to Dr Claire Simeone, Veterinary Science, The Marine Mammal Center, Sausalito, CA 94965, USA; simeonec{at}tmmc.org

Abstract

Stranded California sea lions considered unable to survive in the wild are often placed in public display facilities. Exposure to the biotoxin domoic acid (DA) is a common cause of stranding, and chronic effects are observed long after initial exposure. Medical records for 171 sea lions placed in US institutions between 2000 and 2016 were reviewed, including results from clinical examinations, histopathology, behavioural testing and advanced imaging. There was a statistically significant increase in neurological disease detected in neonates (24%) compared with other age classes (11%). Sixty per cent of all neurological cases died during the study period. In the 11 neurological neonate cases, six died (55%) and five are still alive with three of five developing epilepsy during placement. Of the six neurological neonate cases that died, one was attributed to DA toxicosis, one to seizures and four to acute unexplained neurological disease. This survey suggests delayed neurological disease can develop in sea lions after stranding as neonates. These data coupled with stranding records and epidemiological data on DA-producing algal blooms suggest further research into effects of neonatal exposure to DA on risk of neurological disease in later life is warranted. California sea lions offer a natural model of DA exposure to study such effects.

  • california sea lion
  • domoic acid
  • neurologic
  • public display
  • seizures
  • survival

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Footnotes

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on request.

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