A spike in the number of dead dolphins has been reported washing ashore along the East Coast — and now scientists think they know why.
Culprits may include disease or even polluted seas, the Smithsonian blog reports.
Since July, 124 dead bottlenose dolphins have washed ashore from New Jersey to Virginia, a rate that is seven times higher than normal, according to NOAA.
The federal organization has declared the spike in deaths an "unusual mortality event," which releases funds allowing for further study.
Researchers are still in the early stages of their investigation, but they point to possibilities including pollutants, harmful algal blooms, infectious viruses and injuries due to ship strikes.
One worrisome affliction could be the morbillivirus. At least one dolphin tested positive for the disease. The illness killed 740 dolphins along the East Coast in 1987.
Another theory of what’s causing the dolphin die-off: humans. “What have we done to the marine environment that’s permitting these things to happen?” said the Smithsonian’s Charles Potter to Yahoo News by phone. Potter had just returned from Virginia where he assisted in the investigation. “It’s important to us as humans," he said. "Life as we know it on this planet is dependent on the marine ecosystem. That’s the bottom line.”
Potter noted that males and male calves are dying disproportionately, which could mean the presence of environmental contamination in the water.
“Males don’t have a mechanism for shedding contaminants,” Potter told the Smithsonian blog. “The females shed significant amounts of their lipid-soluble contaminants through lactation, so the calf gets a hell of a dose early on in life, and some of the most outrageous levels of contaminants we’ve seen have been in calves.”
Already this month, 28 dolphin deaths have been reported. Scientists say it could take weeks before their investigation is complete.
“We basically perform necropsies of the carcasses that come in,” Potter said. “We’re assuming nothing and looking at the entire animal for the cause of death.”