The National Oceanic and Atmospheric Administration (NOAA) has declared an unusual mortality event (UME), with more than 261 dolphin strandings since Feb. 1 in the northern Gulf of Mexico including Louisiana, Mississippi, Alabama, and the Florida Panhandle from the Alabama border to Franklin County, according to officials.

According to NOAA, the number of strandings is three times more than the historical average. Locally, Michelle Pettis, chief wildlife rehabilitator at the Emerald Coast Wildlife Refuge, said the refuge's marine mammal stranding team normally responds to about 15 carcass recoveries and one live recovery every year, but as of a few days ago, the team is at 19 responses so far this year.

"It's definitely increased over the last couple months when we've had our most responses," Pettis said.

The cause of the UME is under investigation by a team of scientists. But according to Pettis, the strandings are possibly attributed to dolphins being exposed to freshwater that was released into the Gulf from the opening of the Bonnet Carre Spillway, a flood control operation in Louisiana.

Dolphins that have been recovered have been decomposed, which has made it difficult to determine cause of death or illness. But some stranded dolphins have visible skin lesions, consistent with freshwater exposure, NOAA said.

For the Emerald Coast Wildlife Refuge, the declaration makes its marine mammal stranding team, which responds to local standings, more alert and focused, Pettis said.

"I believe it was around the month of March where we had maybe four standings in one week, which is a lot for us," Pettis said. "We usually don't get so many."

The stranding team, authorized by NOAA, has been in the western Florida Panhandle since 1994. It consists of about 20 people, including specialists that work at the refuge and volunteers. With the increase in strandings, Pettis said more help is needed.

"We set aside a whole other training session, so we are now welcoming additional volunteers onto the team to apply," Pettis said.

NOAA is asking the public to assist in the investigation by immediately reporting any sightings of dolphins in distress or stranded by calling 877-942-5343. The public can also call a nearby stranding team, which would be the wildlife refuge for the Emerald Coast. Pettis said it's important to not touch the stranded animal in case of a disease that can be transferred to humans.

"(Beachgoers) should be aware of what has been happening and know that this may mean that they are now more likely to see a stranded live marine mammal or perhaps a carcass that has just washed ashore," Pettis said.