KEY POINTS:
A little green turtle hooked on a fisher's line under the Auckland Harbour Bridge is today expected to be swimming freely in a marine reserve off Northland's east coast.
The turtle was one of three to be released back into their natural environment this morning after about a two-year recuperative stint in Kelly Tarlton's aquarium.
The curator at Kelly Tarlton's Antarctic Encounter and Underwater World, Andrew Christie, said the three protected turtles were part of a threatened population. .
Two had been washed up in Northland, on the Kaipara coast and in Whangarei Harbour, and the other was caught after swallowing a fish hook on a longline from a recreational boat in the Waitemata Harbour.
Mr Christie said about four to six injured turtles were rescued from New Zealand waters each year.
"When animals like these green turtles come to us, they are usually extremely sick or injured. The process of bringing them back to full health and rehabilitating them so they have the best survival rate possible is a long process - usually one to two years."
Usually distressed and exhausted on arrival the animals were treated by Kelly Tarlton's curatorial team and kept in shallow water during their initial recovery.
Once out of danger they were moved to the 1 million-litre fish tank to build up their strength.
The turtles, about 50cm by 60cm, had been nicely fattened on a diet of north-Atlantic herrings and mussels.
Rescued animals generally doubled their weight during rehabilitation helping to ensure they had the best possible start when back in the wild.
Mr Christie said out in the wild they would likely resume living on a diet with more vegetation including seaweeds.
Because turtles were cold blooded they were predominantly found in warmer waters so it was the last opportunity this year to reintroduce them to a natural habitat before winter's chill set in.
The three rehabilitated turtles were released at the Poor Knights Islands where there was plentiful food, and the nearby east-Auckland current provided an ocean highway by which they could take off to other parts of the Pacific ocean when they were ready.
Mr Christie said green turtles had been spotted during the summer at the Poor Knights, and the new turtle trio had been fitted with identification tags for any future sightings.
Although several species of turtles frequented New Zealand's warmer northern regions, as far south as the Coromandel peninsula, they were still a relatively uncommon sight.
Kelly Tarlton's has two more recovering turtles, a loggerhead and a hawksbill.
