The 10-year-old turtle was originally caught and satellite tagged by NSW Department of Primary Industries scientists David Harasti and Christopher Gallen in January.

"Since then Kelpie has been popular with divers and snorkelers who see her regularly at Fly Point," Mr Harasti said.

In July, the Examiner reported the concern snorkelers had about the amount of rubbish floating in the water at Fly Point.

One month later, in August, divers reported Kelpie was looking unwell.

She was recaptured and taken to Taronga Wildlife Hospital in Sydney where she received six weeks of veterinary treatment for a mysterious illness that had caused her to lose body weight and stop feeding.

"If left untreated it would be certain that Kelpie's fate would be similar to other turtles that had suffered the same mystery illness and sadly died," Mr Harasti said.

Following successful rehabilitation, on the October long weekend Kelpie was released back into her home waters by snorkeler and turtle enthusiast Tania Rossiter.

Kelpie is one of several turtles that DPI staff are currently monitoring in the Port Stephens-Great Lakes Marine Park.

The research collated from the tagged turtles has helped scientists identify key threats affecting the population of resident turtles in the marine park, determine their foraging areas and provide an insight into movement patterns. Green sea turtles are an endangered species.