The U.S. Geological Survey report released Feb. 28, 2014, concludes sea otters in Alaska's Prince William Sound have recovered to levels seen before the Exxon Valdez oil spill nearly 25 years ago. / Mark Thiessen AP
ANCHORAGE, Alaska (AP) - A federal agency says sea otters in Alaska's Prince William Sound have recovered to levels seen before the Exxon Valdez oil spill.
A U.S. Geological Survey study released Friday says crude oil that remained contributed to sea otter deaths and lower population numbers.
Research scientist Brenda Ballachey (bah-LACH'-ee) says a lesson to take away is that the chronic effects of oil in the environment can persist for decades.
The supertanker ran aground nearly 25 years ago and released 10.8 million gallons of crude oil, which flowed southwest as far as Kodiak Island.
Carcasses of about 1,000 sea otters were recovered soon after the spill. Ballachey says the deaths of a similar number of sea otters in later years likely were tied to oil that persisted in the sound.
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Read the original story: Sea otters declared recovered following 1989 spill