It took about twenty-five years, but the northern sea otters (Enhydra lutris kenyoni) living in Alaska’s Prince William Sound have finally recovered from the effects of the 1989 Exxon Valdez oil spill, according to a new report from the U.S. Geological Survey (USGS).
Back on March 24, 1989, the oil spill itself killed an estimated 40% of the sea otters living in the sound. The Exxon Valdez Oil Spill Trustee Council was created to oversee restoration of the Prince William Sound ecosystem and was funded by a $900-million civil court settlement after the disaster. The council blames the mortality rates and slow recovery on “chronic exposure to hydrocarbons” that persisted in the environment, especially in the otters’ feeding grounds.
In 1993, scientists started conducting annual aerial surveys of sea otters in Prince William Sound. The population returned to health in 2008 and 2009. Since then the numbers have risen nicely; the USGS reports that the main sea otter population in the sound was 4,277 last year.
Recovery also was assessed using studies to detect oil exposure using gene expression as a biochemical indicator. The most recent genetic evidence suggested a reduction in oil exposure since 2008.
Scientists concluded that the status of sea otters in western Prince William Sound is now consistent with the criteria established for population recovery set by the Exxon Valdez Oil Spill Trustee Council.
Happy Ottersday :#)
The publication “2013 update on sea otter studies to assess chronic injury from the 1989 Exxon Valdez oil spill, Prince William Sound, Alaska” is available online.