Dolphin freed from rope

A rescue operation has freed a port river dolphin caught up in three metres of rope in South Australia.

The 10-year-old dolphin has a deep scar in its tail fin and keeps getting entangled.

It is the fourth time it has been rescued and surgery is now being considered to remove the groove in its tail.

Whale and Dolphin Conservation Society spokesman Dr Mike Bossley says the dolphin was found with the rope on Sunday.

"The longer it was left there, the deeper it would cut into the tail and possibly eventually even sever the tail, and that would have killed the dolphin," he said.

"Probably alternatively, if the rope had become entangled in something else - caught around a pylon or something - and the dolphin couldn't come up for air, it would have died."