‘Unusual Mortality Event’: Hundreds of Dead Dolphins Wash Up on US Gulf Coast

More than 260 bottlenose dolphins have washed up dead along the US Gulf Coast over the last five months, which is three times more than average, according to the National Oceanic Atmospheric Administration (NOAA)

The event has been declared an “unusual mortality event” (UME) by the scientific agency.

A UME is defined by NOAA as “a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response.” 

“It is too early to determine any potential causes of the UME. Many of the dolphins recovered are very decomposed, limiting the ability to collect samples to determine the cause of illness or death,” NOAA wrote in a recent press release.

Many of the dolphins are stranded in remote locations in Louisiana, Mississippi, Alabama and the Florida panhandle, which limits the agency’s ability to “examine or recover” the carcasses, the press release adds. 

However, NOAA also notes that some of the dolphins have visible skin lesions typically linked to fresh water exposure. Excessive fresh water in the Gulf related to flooding caused by excess rain and melting snow could affect the salinity of water along the Gulf Coast. Dolphins typically live in saltwater environments, as does most of their prey.

“DON’T push the animal back out to sea!” NOAA warns on its website to those who find a beached dolphin or other mammal. “Stranded marine mammals may be sick or injured. Returning animals to sea delays examination and treatment and often results in the animal re-stranding in worse condition.”