Marine scientists are examining the deaths of 20 baby dolphins whose carcasses have washed ashore in Mississippi and Alabama this year, the bulk of them since last week, researchers said on Tuesday.

By Leigh Coleman

BILOXI, Mississippi (Reuters) – Marine scientists are examining the deaths of 20 baby dolphins whose carcasses have washed ashore in Mississippi and Alabama this year, the bulk of them since last week, researchers said on Tuesday.

The unusually large number of young dolphin deaths are being looked at as possible casualties of oil that fouled the Gulf of Mexico for months after a BP PLC drilling platform exploded in April 2010, killing 11 people and rupturing a wellhead on the sea floor.

The bodies of 20 infant and stillborn dolphins have been discovered since January 20, most of them during the past week, on islands and beaches along a 130-mile stretch of coastline from Gulfport, Mississippi, east to Gulf Shores, Alabama.

That’s about 10 times the number normally found washed up along those two states during this time of the year, which is calving season for some 2,000 to 5,000 dolphins in the region, said Moby Solangi, director of the Institute of Marine Mammal Studies in Gulfport.

The remains of about 10 adult dolphins, none of them pregnant females, have also been found so far this year.

BP cleanup crews found some of the carcasses. Others were discovered by park rangers, law enforcement officers and passersby.

The young dolphins, some barely 3 feet in length, appeared to have either died shortly after birth or were aborted just before reaching maturity, he said.

“For some reason, they’ve started aborting or they were dead before they were born,” Solangi said. “The average is one or two a month.”

None of the carcasses bore any obvious outward signs of oil contamination. But Solangi said necropsies, the equivalent of human autopsies, were being performed and tissue samples taken to determine if toxic chemicals from the oil spill may have been a factor in the deaths.

Documented mortality in the adult dolphin population off Mississippi and Alabama roughly tripled from normal numbers last year, climbing from about 30 typically reported in a given year to 89 in 2010, Solangi said.

Officials from the Mississippi Department of Marine Resources and the U.S. National Marine Fisheries Service also were taking part in the investigation, he said.

(Writing by Steve Gorman; Editing by Peter Bohan.)