Chapter 10: Animal Health and Welfare Considerations

SHORT SUMMARY:

Chapter 10 addresses sea otter health and welfare considerations inherent in a potential sea otter reintroduction to Oregon. A rich and extensive literature exists on sea otter health, disease, and environmental threats in other regions. Many previously reported diseases and threats could affect the success of a newly established sea otter population in Oregon. While it is impossible to predict all of the potential health threats that may exist in the future or that might occur cryptically along a coastline free from sea otters for more than a century, a good faith effort is needed to identify those threats of greatest concern before a sea otter reintroduction commences.

The most substantial health threat to sea otters reintroduced along the Oregon coast would probably come from domoic acid intoxication. The presence of domoic acid in shellfish can cause intoxication of shellfish consumers, and research has shown that even low levels can drive cardiac disease in sea otters. Bites from white sharks cause significant mortality in southern sea otters. Although population numbers and locations of white sharks along the Oregon coast are unknown, shark bites could affect the growth rates of reintroduced sea otter groups. Another species, the broadnose sevengill shark, is present in high numbers in Oregon’s coastal, offshore, and estuarine systems and could be a potential sea otter predator.

It is unlikely that infectious disease would have population-level impacts on a sea otter reintroduction program but could have a significant impact on otter health in specific areas and over time as otter numbers expand. A contagious disease, such as a morbillivirus infection, could also have an epizootic effect within localized areas. The potential for disease exposure and transmission may argue for multiple releases of sea otters into multiple areas of the Oregon coast. A summary table is presented in Chapter 10 that ranks the population-level risks to sea otters of the various diseases described within the chapter.