Since January 1, 80 dead dolphins have been discovered along the coasts of Louisiana, Mississippi, Alabama, and Florida, according to the latest NOAA figures.
Forty-two of the dead were calves. Most of the juvenile dolphins are washing up in Mississippi and Alabama, because dolphins typically give birth and raise calves along the shallow shores of those states.
The normal gestation period for the dolphins is one year, and mothers usually give birth in March and April, so scientists think the affected calves are either being aborted, stillborn, or born prematurely.
"That's one part of the investigation that we're going to be looking at very carefully," Mase said.
"We'll methodically score each animal that has come ashore to determine if, in fact, it was an aborted calf or an animal born alive."
BP Oil Spill "a Factor We Need to Consider"
Dolphin die-offs—which scientists call unusual mortality events—occur every few years. But this one stands out, because young dolphins appear to be hardest hit, marine biologist Moby Solangi said.
"Usually in a stranding, you have a mixture of animals—males, females, adults, calves—but this one is distortedly focused on neonates," said Solangi, director of the Institute for Marine Mammal Studies (IMMS) in Gulfport, Mississippi, which is helping to investigate the deaths.
Also unusual: Only dolphins appear to be affected so far. No mass deaths of turtles, fish, or birds have been reported for this die-off. (Also see "Why Are Birds Falling From the Sky?")
Known causes of dolphin die-offs include unusually cold waters, ocean biotoxins, and diseases.
NOAA's Mase said scientists are investigating all of these factors and are not ruling out a possible connection to the BP oil spill.
"It's something that we are including in our investigation," Mase said.
IMMS's Solangi agreed that the BP oil spill "is a factor that we need to consider."
"The oil spill lasted several months, and it covered tens of thousands of square miles and much of the habitat of these animals."
IMMS scientists are currently performing necropsies on the dead dolphins to try to determine causes of death. The process—including analyzing tissue samples for signs of diseases, viral infections, and toxins—could take several weeks or months, Solangi said.
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