Dolphins Dying in Abnormal Numbers Along East Coast, But Why?

Unusually high numbers of bottlenose dolphins dying along the U.S. East Coast this summer has researchers racing to find the cause of what may be the most deadly season for the marine mammals in 25 years.

As of Tuesday, 228 dolphin deaths from New York to Virginia have been recorded, compared to 111 deaths for all of 2012, CNN reported.

In Virginia, 78 dolphins washed ashore so far this month.

Urgent: Should Obamacare be Repealed? Vote Here Now

In response to the deaths, the National Oceanic and Atmospheric Administration issued an Unusual Mortality Event. The declaration brings special federal attention to deaths as something that serves as an indicator of ocean health and may give "insight into larger environmental issues which may also have implications for human health and welfare," according to NOAA's website.

Dying dolphins may be sending a warning, Susan Barco, research coordinator for the Virginia Aquarium and Marine Science Center, told CNN.

“Bottlenose dolphins are a higher-order predator. They're often referred to as 'ocean sentinels of health.' So when our bottlenose dolphins are healthy, it would probably indicate that we have a fairly healthy ecosystem. When our bottlenose dolphins are not healthy, it may very well indicate that our ecosystem is not healthy.”

Barco says she fears that the disease and deaths could continue through the fall migration and spread as far as Florida.

Prior to this summer, the last big die-off occurred in 1987 when 740 dolphins expired along the East Coast, the Star-Ledger reported. Those deaths were linked to morbillivirus, a virus found in dolphins that is similar to canine distemper.

Online, CNN commenters posted their own theories about the dolphin deaths.

“What's killing the dolphins? How about the chemicals dumped into the water after that humongous oil spill,” wrote one reader. “Japan is leaking radiation all over the place, and there's a gigantic mass of plastic and garbage swirling in the middle of the ocean. Are we really this stupid?"

Another poster said it’s part of the natural order. “99.9 percent of all species that have existed on Earth are extinct. Stop blaming humans as nature is the prime culprit.”

Latest: Do You Support Giving Illegals Citizenship? Vote Here Now

Related stories:

Chinese Dying Dolphin Is Photo Op Instead of Cause for Concern (Video)

Dolphins Names: Each Has a Unique Sound That Others Call It By