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 Alaskan
or northern sea otters were once brought to near extinction by
the fur trade. Protected by the Marine Mammal Protection Act
of 1972, their numbers rebounded significantly. However, since
the mid-1980s the northern sea otter population has declined
by roughly 56-68 percent in the past 20 years. There are many
theories about this decline but no one really knows its true
cause.
Dr. Verena Gill, a pathologist with the U.S. Fish and Wildlife
Service, and her team have proposed a project to attempt to answer
the question of whether the prevalence of infectious disease
is higher in the southern sea otter subspecies as opposed to
the northern subspecies. This project will help identify if disease
is an issue with northern sea otter populations and if it is, what diseases are
present in northern sea otters as compared to the southern or California sea
otter. Gill believes that low-level pathogens are a part of all sea otter species
and may not be an issue in a healthy growing population. However, a population
that becomes severely stressed by the effects of oil spills “could be dramatically
reduced in numbers in a relatively short period of time. The specific objectives
of this study are:
1. To obtain sea otter carcasses throughout Alaska from a variety
of sources
2. To perform complete necropsies on carcasses to assess prevalence
of disease and determine cause of death
3. To radiograph all carcasses to assess skeletal injuries
4. To compare the causes of mortality and prevalence of infectious
disease agents in northern sea otters with the prevalence in
southern sea otters.
This in situ study will contribute to the conservation of the
northern sea otter, a keystone species in the marine environment
whose health is vital to the health of the ecosystem as a whole.
The Minnesota Zoo’s Ulysses S. Seal Conservation Grant Program awarded “Prevalence
of infectious disease as a cause of mortality in Northern Sea
Otters (Enhydra lutris kenyoni) in Alaska” $2500 in 2005
for its efforts to determine what is causing the decline in the
remaining population of northern sea otters.
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