"The life expectancy of his transmitter is one year, so it's not an absolute definite that something has occurred to the animal."
Nebs was one of three green turtles being tracked by Mr Godoy and was released just south of Cape Brett in February last year. From then until July, Nebs had swum more than 2000km, going as far as the East Cape.
Mr Godoy said one of the other turtles, which was originally released on the coast near Kaitaia, had "bunkered down for the winter" near Paringaringa.
He hopes Nebs has done the same. "The thing is, Nebs survived over a year in rehabilitation."
In August 2011, Nebs was found sick on Karekare Beach in Auckland, having eaten plastic marine debris. He spent nearly two years at the rehabilitation centre at Kelly Tarlton's Sealife Aquarium in Auckland and, when released by Mr Godoy in 2013, weighed 14kg. He was estimated to be about 8 or 9 years old.
Mr Godoy did not discount the possibility of Nebs being eaten by an orca. "It's not their primary predator, but I have encountered a turtle chomped to pieces in Mission Bay on a day where orca were around chasing stingrays."
Anyone finding Nebs, the transmitter or any other turtles should call the Department of Conservation on 0800362468.