From the Exxon Valdez Oil Spill (EVOS) Trustee Council Fiscal Year '95 Project Description:
" River otters inhabiting marine environments make extensive use of, and concentrate their activities in, intertidal and subtidal zones. These high trophic-level carnivores are long-lived, and occur at densities of 0.2-0.8 otters/km of shoreline throughout the Gulf of Alaska. River otters are extremely sensitive to aquatic pollutants, yet continued to reside within the area of oil-contaminated shorelines in PWS, Alaska following the spill. These characteristics make river otters an excellent model for assessing effects of marine pollution on mammals, and provide an overall index to the health of the nearshore ecosystem.
River otters living in marine environments consume a diet dominated by marine fishes, which they prey upon in intertidal and subtidal zones; they also consume a wide variety of marine invertebrates. Such nearshore areas are the most often affected by pollution. For instance, the spill contaminated extensive areas of the intertidal and subtidal environments, which was reflected in a loss of dietary diversity for otters inhabiting oil-contaminated shorelines. Likewise, river otters living in oiled areas exhibited a significantly lower body mass (when controlled for sex and total body length) than did otters inhabiting unoiled areas. Otters have extremely large home ranges (20-40 km of shoreline), and hence integrate effects of pollution over wide areas.
Population dynamics of European otters (Lutra lutra) in coastal areas have been linked to the abundance of marine fishes; this is also likely the case for river otters inhabiting PWS. It was previously demonstrated that diversity of otter diets declined significantly following the spill. Similarly, body mass of otters was significantly lower on oiled, compared with unoiled, areas of PWS."
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