Sea turtles' favourite Kiwi hangouts revealed

The secret adventures of turtles have been revealed thanks to satellite trackers.

Researchers have been following green sea turtles, finding out where they hang out and how far they travel.

One of the big findings is that they don't breed here.

Department of Conservation (DOC) marine senior science advisor Dr Karen Middlemiss is the project lead of Team Turtle.

"It's a fantastic way to keep an eye on where they are from a distance, and we can let them carry out their kind of normal daily routines without interfering," she told Checkpoint, whilst literally watching five turtles' movements live on her computer screen.

"It's a bit boring from my side of things. They just have a number based on the tag. There are a couple of turtles that were named by some children... which was pretty cool. And yeah, they are the ones that just got a boring number, I'm afraid."

The 11 rescued turtles were rehabilitated at Kelly Tarlton's, an underwater aquarium in Auckland. The tags are temporary, lasting about the life of their batteries - up to 12 months.

Middlemiss said contrary to popular belief, turtles are "pretty good at zoomies" and "can motor when they want to".

"They also do travel vast distances through the ocean, as we've seen from some of our tracking data. One of them went all the way down to Wellington and on a bit of a trip and then all the way back up to Northland again."

She said it wasn't clear why that turtle decided to go to Wellington, but it may have been for the food. It also made a month-long pitstop in Auckland's Manukau Harbour.

"And they travel across the Pacific between their foraging grounds and nesting beaches, so it's not unusual to see them travel long distance."

The research showed turtles were particularly keen on Rangaunu Bay and Harbour, Pārengarenga Harbour, Murimotu, Whangārei Harbour and the Bay of Islands in Northland, and Manukau Harbour. While many like to stay in one particular harbour for lengthy periods, they all eventually leave, using New Zealand as a "baby-sitting service for teenagers" and choosing to breed elsewhere. The tagged turtles are tracked using the new Kinéis constellation of 25 satellites.

"As an organisation dedicated to marine conservation, it's incredibly rewarding to gain a clearer picture of how green sea turtles are using New Zealand waters," Kelly Tarlton's general manager Dan Henderson said in a statement.

"These findings highlight just how connected our marine environments are and reinforce the importance of protecting critical habitats along our coastline."

Auckland Zoo veterinary services manager Dr James Chatterton said there had been eight unwell turtles arriving since June.

"We see a range of illnesses including trauma (fishhooks, line entanglement and boat strike), as well as diseases secondary to immune suppression such as pneumonia and intestinal infections.

"We suspect the immunosuppression is impacted by reduced access to food and/or degradation of their marine environment."

Middlemiss said there were ways boaties could avoid hitting turtles.

"When you're out there this summer on the harbour you can try and get someone to be a lookout on the boat and let the captain know. If you can put a propeller guard on the boat that would be fantastic, to kind of minimise injuries.

"And just slow down when you know you're in an area where you might see them frequently, because they just pop up to breathe and you might not notice them there and unfortunately that's when we get these vessel strikes happening."