The number of dolphins and whales killed in the aftermath of the Deepwater Horizon spill has likely been significantly underestimated, according to a new analysis. While a reported 101 whale and dolphin 
carcasses have washed ashore in the Gulf of Mexico since last April’s spill, the actual death toll could be as much as 50 times higher, since most of the animals likely died far from shore and were never recovered, according to a report published in the journal Conservation Letters. Using recent species abundance estimates, mortality rates, and historical data on observed strandings for 14 species of cetaceans — an order of mammals that includes dolphins and whales — the researchers calculated that only 2 percent of carcasses are ever recovered in the Gulf region. The difficulty of obtaining a more accurate estimate of cetacean deaths has been compounded by the fact that the spill occurred 40 miles offshore and oil drifted hundreds of miles from coastlines, said Rob Williams, a researcher at the University of British Columbia’s Marine Mammal Research Unit and lead author of the study.
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