A bottlenose dolphin that has been swimming off the Kent coast since last year has sustained injuries apparently from a boat propeller.
Dave the dolphin has become very used to human contact
The dolphin, named Dave before it recently emerged that she was female, has parallel cuts on her dorsal fin.
Experts have said the wound is not considered to be life-threatening, but have warned that it could lead to an infection which could prove fatal.
Swimmers and boats have recently been ignoring advice to keep away from her.
Dave has been living in the Channel off Sandgate since last April and has become so used to human contact that there have been recent reports of people trying to ride on her back.
The Whale and Dolphin Conservation Society (WDCS) said it had been warning for many months that Dave was becoming increasingly vulnerable as a result.
"The situation is increasingly dangerous for Dave and for people in the water with her," a spokesman said.
"This wound is relatively small but many friendly dolphins are killed by propeller strikes and what this latest development reinforces is the need for people to watch her only from the shore."