Two red-eared slider turtles - a young hatchling and a more mature specimen. Photo: RNZ / Libby Kirkby-McLeod
Visitors to Hamilton gardens can go reptile spotting at Turtle Lake, but the red-eared slider turtles the lake is named after are a global pest that do not belong in New Zealand's waterways.
The global Invasive Species Specialist Group classified red-eared slider turtles as one of the world's 100 worst invasive species more than 20 years ago.
Turtle Lake is not the only waterway in Waikato where the unwanted reptiles can now be found and Danielle Kruger from the Waikato Regional Council says none of our freshwater environments have evolved to adapt to their presence.
She said that was a major problem.
"It's not likely that native species would see them as a food source as they just haven't encountered something similar," she said.
Rather than being a food source for native species, they are a competitor for food.
"We've got an ecosystem that is already under stress for a number of other reasons and it's just one more organism to compete."
Her message to pet turtle owners was simple - please don't put them in our waterways.
"They're not from here, they don't belong in our waterways."
Turtle Lake in Hamilton Gardens is full of red-eared slider turtles. Photo: RNZ / Libby Kirkby-McLeod
RNZ asked some visitors at Turtle Lake what they thought about the wild turtles - and they tended to think the city should live and let live with the turtles.
"If we brought them here we should take care of them...as long as they're not breeding and creating too much havoc, leave them alone," said one.
But the problem was the breeding, said University of Waikato associate professor in Biodiversity and Ecology Nick Ling.
He said there was evidence red-eared slider turtles were now able to multiply in the wild in the Waikato region after a population in the Coromandel was found to be breeding in 2015.
"Subsequent to that we've found that they are far more widespread than we initially thought, and that breeding is occurring in a number of different places."
The turtle sculptures in the lake. Photo: RNZ / Libby Kirkby-McLeod
Ling said he was really concerned about what impact the turtles might have on freshwater environments that were already stressed, pointing out that one female can lay 400 eggs in her lifetime.
Auckland has banned the breeding, distribution and sale of the turtles, but they can still be easily bought in Waikato.
The National Pest Pet Biosecurity Accord was set up in 2015 to bring a national approach to the pest pet problem.
Ling said it would help if the turtle was listed on the accord. But anything on the accord needed to be on the unwanted organisms register, which would have unwanted consequences for pet owners.
"If you were to make red-eared slider turtles an unwanted organism in New Zealand, what that would do is instantly criminalise all those people who have the turtles as pets," said Ling.
University of Waikato associate professor in Biodiversity and Ecology Nick Ling with two red-eared slider turtles. Photo: RNZ / Libby Kirkby-McLeod
No animals have been added to the Accord List in the past nine years.
Biosecurity New Zealand director of readiness and response John Walsh said it was a complicated issue.
"The Accord, published in 2015, was a memorandum of understanding signalling intent/commitment to jointly do further work, particularly around pest prioritisation. However, despite our best efforts, it has been difficult to get all parties to agree how to implement the Accord, which is why we consider it is still a work in progress."
Ling said it would be a a good start if the accord can become a usable tool to prevent the sale of red-eared slider turtles. But with the turtles now breeding across the Waikato, there was still a lot of work to do.
