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Is the Oil Spill Affecting the Gulf’s Sperm Whales?
A sick and severely emaciated adolescent female sperm whale was found beached on the Florida coast near Tampa on Halloween. After the necropsy, officials said there were indications of an infection in the abdominal cavity and a large of amount of fluid around the whale’s heart. Lab results will be completed in a few weeks.
While this particular animal’s death may or may not end up linked to the Gulf oil disaster, its untimely demise highlights the need for more research on the Gulf’s sperm whales—as there are plenty of reasons for concern.
Scientists estimate there are about 1,500 sperm whales in the Gulf. The Gulf’s sperm whales are smaller than sperm whales elsewhere in the world and use distinct calls and vocalizations. These animals live year-round off the continental shelf, and can often be found in the region southwest of the Mississippi River Delta—the area where Deepwater Horizon was located.
Even decades after commercial whaling was outlawed, the species remains endangered. In fact, the National Oceanic and Atmospheric Administration (NOAA) estimates that the potential biological removal level for the Gulf of Mexico sperm whale population is just three whales annually. As National Geographic News explains:
… the whales’ long-term survival is at risk if, in addition to natural deaths, three sperm whales a year are killed or removed by human causes.
The loss of a handful of whales each year can impact a population of hundreds, because sperm whales—especially females—require a very long time to reach sexual maturity. Females then give birth to just three or four calves during their entire lifetimes.
“As soon as we get to the level of three deaths caused by human interaction—and this would include the oil spill—that would jeopardize that particular sperm whale population.”
However, if sperm whales are dying in higher numbers in the wake of the spill, scientists simply might not know. Typically only a tiny percentage of dolphin and whale carcasses are ever found.
In 2010, however, the waters of the Gulf of Mexico were thick with boats. Seven weeks into the disaster, a research expedition came across the body of a juvenile sperm whale 77 miles from the site of the disaster. NOAA tried to downplay the news by not making photographs of the whale publicly available. The animal was so badly decomposed NOAA was unable to determine a cause of death.
There is evidence that some sperm whales moved away from the most heavily oiled areas while the disaster was ongoing. But that does not mean that the sperm whales were not impacted by the disaster.
Researcher John Wise at the University of Maine found that metals that damage DNA are found in higher levels in sperm whales in the Gulf of Mexico than in other sperm whales elsewhere in the world. These metals are also present in the oil that spewed from BP’s well.
Genotoxic metals, such as chromium and nickel, damage DNA and bioaccumulate in organisms resulting in longer exposures. Analysis of sperm whale skin samples showed mean levels of Ni and Cr at significantly higher levels than those found in whales collected around the world prior to the spill. … Maps of where we collected our samples showed the highest metal levels in whales closest to the epicenter.
The young whale found on Halloween could have been exposed to oil that settled on a shelf approximately 80 miles from the Tampa Bay region.
More science is needed to understand the impact of the disaster on wildlife, including sperm whales. And while studies are ongoing, it is also clear that important research simply is not being done. The magazine On Earth reported that BP’s grant program rejected a proposal from the University of Maine’s Wise to continue his research on sperm whales–apparently because the reviewers said whales were not important players in the ecosystem.