THE world's oldest known tagged turtle has returned to Mon Repos for her 13th nesting enchanting visitors, rangers and scientists.
Department of Environment and Heritage Protection chief scientist Dr Colin Limpus said the flatback turtle came ashore last week laying a clutch of 61 eggs.
He said she was first tagged 39 years ago as she began her breeding life.
"Turtles like this are teaching us how long these animals live for and how long they can breed for," Dr Limpus said.
"Our program is one of the few in the world that has a tagging system that has been running long enough to actually be giving us new information."
Estimated to be about 60 years old, the flatback turtle known by her first tag number X23103, has been recorded at the beach 69 times in the past 39 years.
"And all those times she has nested here at Mon Repos, which is extraordinary in itself," Dr Limpus said.
"One of the features of Mon Repos is that it is one of the most stable beaches in the region but how the turtles recognise that remains a mystery.
"If you look at turtle nesting up and down the coast more turtles nest at Mon Repos than all the beaches in the region combined."
Dr Limpus said other beaches in the region, such as Moore Park Beach, tend to be vulnerable during cyclone season where all eggs could perish.
Female flatbacks begin breeding at 21 and lay eggs every two years and X23103 is showing no signs of slowing down laying more than 60 eggs per clutch.
"Female flatbacks average 50 eggs per clutch so that is an above average clutch," Dr Limpus said.
"There is no sign in decline in her breeding so it will be interesting to see if she comes back in two years."
Mon Repos visitors will not have to wait too long however as X23103 is expected to return next week.
"We will be on the beach looking for her," Dr Limpus said.