The National Wildlife Federation continues to track dolphin deaths along the Gulf Coast. Today we’re learning some alarming new numbers about dead dolphins washing ashore in the heart of the area impacted by the Gulf oil disaster:

The National Oceanic and Atmospheric Administration says the number of dead dolphins found since Jan. 1 in the area affected by last year’s oil spill is now 67, with 35 of them premature or newborn calves. [National Oceanic and Atmospheric Administration] regional spokeswoman Kim Amendola says five dead calves were reported Friday in Mississippi or Alabama.

Federal officials are taking action in response to the wave of dolphin deaths:

The National Oceanic and Atmospheric Administration declared the alarming cluster of recent dolphin deaths “an unusual mortality event,” agency spokeswoman Blair Mase told Reuters. “Because of this declaration, many resources are expected to be allocated to investigating this phenomenon,” she said. Although none of the carcasses bore outward signs of oil contamination, all were being examined as possible casualties of petrochemicals that fouled the Gulf of Mexico after a BP drilling platform exploded in April 2010, rupturing a wellhead on the sea floor, officials said.

Dr. Doug Inkley, senior scientist with the National Wildlife Federation, said today:

While any dolphin deaths are disturbing, there’s no way to know what killed these dolphins before necropsies are performed, and even those may not provide concrete answers. A number of factors could be in play, from disease to food shortages. Considering we know both living and dead dolphins were found with oil on them during the early months of the oil disaster, it’s fair to ask if toxic oil or dispersants could have played a role here. There could also be sickening-but-not-deadly oil effects on adult dolphins that have inhibited successful reproduction. While we do not yet know if these dolphin deaths were associated with the Gulf oil gusher, we do know that the environmental health of the Gulf of Mexico has been in serious decline for a long time, a decline made even worse by the oil disaster. These dolphin deaths and the struggles of other wildlife in the region remind us that all wildlife need healthy places to live and raise their young, and the Gulf is in need of a large-scale restoration investment to provide these habitats.

Dr. Inkley and other National Wildlife Federation staffers have exhaustively cataloged the wildlife deaths documented in the disaster zone last spring and summer, including thousands of birds, hundreds of endangered sea turtles, and dozens of dolphins.

Watch Dr. Inkley discuss the dolphin deaths on CNN’s American Morning: