Dead dolphin in SA was shot

A young dolphin found dead in waters off Adelaide had been shot, a post-mortem examination has revealed.

Environment department ranger Janine Kraehenbuehl said, while the cause of death could not be identified, a shotgun pellet was found in the dolphin's dorsal fin.

The young bottlenose was found at Outer Harbour earlier this month, about two kilometres offshore.

Dolphins a protected species and Ms Kraehenbuehl said the discovery of the pellet was disturbing.

"Dolphins are considered by many to be playful and carefree marine mammals and it's distressing to think someone would injure one, either intentionally or accidentally," she said on Wednesday.

"While the pellet may not have contributed to its death, the discovery is a reminder to people to take care."

In South Australia the maximum penalty for killing or wilfully injuring a protected marine mammal is a $100,000 fine or two years in jail.