Dolphin found dead on MS Coast. Damage to body has scientists concerned

The call came Sunday: A dolphin was dead on the beach in Bay St. Louis.

Staff at the Institute for Marine Mammal Studies found it covered in freshwater lesions, said Moby Solangi, the organization’s director. That was troubling.

Dolphins are at the top of the food chain. “When they start dying,” Solangi said, “that’s a cause of alarm.”

The bottlenose dolphin was male, about a year old and had likely been dead several days, Solangi said. Staff recovered its body and were conducting a necropsy, or animal autopsy, on Monday.

Stranded dolphins are not unusual in Mississippi, especially in spring and summer when mothers come to shallow water to give birth. Solangi said nearly 20 dolphins have already washed up on beaches this year.

But he said freshwater lesions on the dolphin in Bay St. Louis suggest salinity levels could be sinking in the western Mississippi Sound.

Too much freshwater can be dangerous for dolphins. The toll became especially clear in 2019 when the the U.S. Army Corps of Engineers opened the Bonnet Carré Spillway, a flood control structure in New Orleans. The opening sent tons of freshwater from the Mississippi River into the Mississippi Sound and killed creatures across the food chain.

The spillway could open again this year because major river flooding is expected through June. Leaders have said if the spillway opens, it probably would not stay open for long.

Scientists cannot draw large conclusions from one animal, and Solangi said the trends driving dolphin deaths this year are not yet clear. There are usually between 30-40 dolphin strandings each year, he said. Stranding season lasts from spring through summer.

Anita Lee contributed reporting.

This story was originally published April 21, 2025 at 3:30 PM.