Wildlife recovery 28 years after Exxon Valdez oil spill

There are now some long awaited answers, 28 years after the devastating Exxon Valdez oil spill in Prince William Sound.

Today, the U.S. Geological Survey released its findings of a wildlife recovery study from the 10 million gallon plus oil spill, in 1989. According to the study, the impacts are highly variable, across the many species, throughout the area.

After decades of research and monitoring, USGS states in a written release that "scientists now know how different wildlife species were injured by the 1989 Exxon Valdez oil spill and how long it took for populations to recover."

The lead author of the study and research wildlife biologist with USGS, Dan Esler, Ph.D., points out, "Because wildlife species in the spill area vary so much, in terms of what they eat, habitats that they use and their ability to rebound after a drop in numbers, researchers saw huge differences in how long it took for populations to recover."

That translated to a wide range of recovery.

"Some species were barely affected, others, such as bald eagles, rebounded quickly and other species took much longer to recover, such as sea otters," said Esler.

Other findings, part of a collaboration between USGS, U.S. Fish and Wildlife Service, Oregon State University and the North Gulf Oceanic Society, identified "ecological factors that affected the degree of injury."

For instance, the study shows:

- Species that foraged on invertebrates that occur in, or on, contaminated sediments were more likely to be affected by the oil spill than those that fed on fish or zooplankton, in the water column.

- Species with low reproductive rates, such as orcas, have limited capacity to recover; in fact, orcas still have not returned to pre-spill numbers.

- Some population changes were not related to the oil spill. For example, two species of seabirds - pigeon guillemots and marbled murrelets - may have been affected by oil exposure, but long-term analyses showed declines in numbers before and after the spill, probably related primarily to changing ocean conditions.

The USGS news release includes the findings of previous long-term studies of sea otters and harlequin ducks, which showed lack of recovery for over two decades after the spill.

"Sea otters were exposed to lingering oil in beach sediments, long after shorelines appeared clean," said USGS Research Wildlife Biologist Dan Monson. "And oil exposure affected survival rates and population growth, until at least the mid-2000s."

To read USGS's recent study, "Timelines and mechanisms of wildlife population recovery following the Exxon Valdez oil spill," follow this

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