Federal authorities are investigating the fatal shooting of a bottlenose dolphin that washed up on a beach in Louisiana last month, according to reports.

The dolphin, a juvenile, was reported to the Southeast Marine Mammal Stranding Hotline on March 13 at Mae's Beach, the National Oceanic and Atmospheric Administration Office of Law Enforcement said in a news release on Tuesday. 

The Audubon Aquarium Rescue, the NOAA's network partner, recovered the animal and transported it to New Orleans. 

An autopsy "revealed multiple bullets lodged in the carcass, including in the brain, spinal cord, and heart of the dolphin. The animal appeared to have died from the trauma, which occurred at or near the time of death," NOAA said. 

A $20,000 reward is being offered to anyone with information that leads to a conviction. 

Tips can be left anonymously at the NOAA Enforcement Hotline at (800) 853-1964.