Base your answer on the information below. A decade after the Exxon Valdez oil tanker spilled millions of gallons of crude [oil] off Prince William Sound in Alaska, most of the fish and wildlife species that were injured have not fully recovered. Only two out of the 28 species, the river otter and the bald eagle, listed as being injured from the 1989 spill are considered to be recovered said a new report, which was released by a coalition of federal and Alaska agencies working to help restore the oil spill region. Eight species are considered to have made little or no progress toward recovery since the spill, including killer whales, harbor seals, and common loons [a type of bird]. Several other species, including sea otters and Pacific herring, have made significant progress toward recovery, but are still not at levels seen before the accident the report said. More than 10.8 million gallons of crude oil spilled into the water when the tanker Exxon Valdez ran aground 25 miles south of Valdez on March 24, 1989. The spill killed an estimated 250,000 seabirds, 2,800 sea otters, 300 harbor seals, 250 bald eagles, and up to 22 killer whales. Billions of salmon and herring eggs, as well as tidal plants and animals, were also smothered in oil. Reuters The oil spilled by the Exxon Valdez tanker is an example of ______________.