Chronic effects of the Exxon Valdez oil spill on blood and enzyme chemistry of river otters

River otters (Lutra canadensis) living in marine environments of Prince William Sound, Alaska, and exposed to crude oil from the Exxon Valdez spill in March 1989 showed elevated levels of blood haptoglobins, and interleukin-6 ir, as well as elevated activities of aspartate aminotransferase, alanine aminotransferase, and creatine kinase in summer 1991. Stepwise logistic regression, using a subset of these and other blood proteins and enzyme activities as potential independent variables, correctly classified 86.4% of 22 otters as inhabiting oiled or nonoiled areas. River otters abandoned latrine sites (an index to their abundance) over three times more often in oiled than in nonoiled areas, suggesting there may have been a delayed response in river otter populations to exposure to crude oil. This is the first clear model for the long-term effects of an oil spill on blood parameters of a free-ranging mammal using a nonlethal methodology. These effects occurred two years after the spill and following a major effort to clean oil from the shorelines of Prince William Sound