The Louisiana Department of Wildlife and Fisheries says biologists did not see any external sign of trauma in a young dolphin found dead along the Mississippi River bank at Baton Rouge.
Spokeswoman Ashley Wethey said Thursday that the body was moderately to severely decomposed when biologists retrieved it by boat on Wednesday for testing.
A hydrologic survey crew reported the body Monday near the U.S. Highway 190 bridge.
Dolphins are a common sight in the salty coastal waters of the Gulf of Mexico. They also frequent brackish bodies of water that connect with the Gulf, such as Lake Pontchartrain.
It's rare for them to get so far upriver.
NOAA Fisheries about bottlenose dolphins: http://1.usa.gov/Sm9XXh