A massive manta ray with a wingspan over 6m-wide has been spotted in Auckland's Hauraki Gulf, and marine scientists are asking boaties to report sightings of the giant fish for conservation records.
Oceanic manta rays are the largest of their kind in the world. (File image) Photo: Supplied
University of Auckland postgraduate student Edy Setyawan said the manta ray was larger than the boat he was on, and he measured it with a drone.
"That's the biggest manta ray I've ever seen. They actually don't look wide because they fold up their wings but when they stretch their wings they're just huge," he said.
"Our boat is six metres in length and the manta ray is just slightly bigger than the boat."
Setyawan and a team have been spotting and measuring manta rays with drones since that sighting in February last year.
It is an extension of his research into reef manta rays in the tropical and subtropical regions of the Indian and Western Pacific Oceans.
"Globally, researchers don't know much about the size of these animals, and knowing the size accurately is very important," he said.
"Using the drones, you can see the claspers of mature males and mating scars on the left wings of sexually mature females. The latter are often difficult to observe via in-water surveys, but using drones they are very obvious."
Setyawan said they were gentle giants known for their graceful swimming and high intelligence.
"They've rarely seen humans so when we jump into the water often they're curious and try to get close and observe us and circle us," he said.
"They don't have barbs or a sting so although they're huge, they can grow up to seven metres in wingspan especially the oceanic manta, they're not dangerous. They can swim very fast but they only use that for escaping from larger predators like other big sharks."
Setyawan said they have identified hot spots around the Hauraki Gulf near outlying islands, including Little Barrier, where the manta rays feed on the surface of the sea.
It is also known as summersault feeding, where the creatures perform somersaults to keep moving but stay in a spot where food is plentiful.
They have even managed to deploy satellite tags on some of the manta rays.
"Some of them ended up in Fiji and south Tonga, 2000 kilometres to the north, so at the moment what we know is they're here during summer and early April, they start migrating north."
Oceanic manta rays are the largest of their kind in the world, with wingspans of seven metres and are considered endangered on the International Union for Conservation of Nature Red List.
Boaties are asked to report any sightings of the fish through Manta Watch New Zealand's social media.