Oil Leak and Dead Dolphins Not Necessarily Connected

May 12, 2010 — -- They may be dramatic, but federal officials are warning that pictures of dead dolphins washing ashore in gulf states may not have anything to do with the oil leak coming from the Deepwater Horizon disaster site.

"Even before this oil spill occurred, we were experiencing unusually high stranding rates," said Blair Mase, NOAA's southeast region marine mammal strandings coordinator.

Dolphin strandings are common, said Mase, who noted that 57 bottlenose dolphins were found stranded on beaches in Florida, Alabama, Mississippi and Louisiana in the month of March alone.

The reasons for dolphin strandings can be a mystery, Mase said, but could have something to do with diseases, extreme water temperatures or algal blooms that release deadly biotoxins.

"It could be a myriad of things," Mase said.

Six dolphins have been found stranded since the oil leak began following an April 20 explosion that killed 11 workers.

The animals were badly decomposed, she said, leading investigators to speculate they may have been dead before the oil spill and are being discovered only now because "there are so many eyes out looking."

None of the dolphins had any visible signs of oil contact, but Mase said the only way to know for sure whether the spill is to blame for their deaths is by completing an examination and sending tissue samples to labs, where they can be tested and studied.

Of the six dead dolphins, a tissue examination called a necropsy has been performed on only one. Partial samples have been taken from another three. Tissue samples, in some cases, go to multiple labs, meaning test results may not be available for several weeks.

In the meantime, Mase said, officials won't rule anything out.

"Because they've come in during this event and because there's a possibility they could have been affected by oil inhalation and that sort of thing, we are going to treat it as an oiled animal," Mase said.