Trial to try to trap tricky turtles
8 Aug 2018
Increased sightings of escaped or dumped turtles in and around Northland waterways have prompted biosecurity experts to trial a new homemade trap made from swimming pool noodles, PVC piping and mesh.
Turtles can do extensive damage to native fish and plants if left uncontrolled and are becoming a more regularly reported problem in Northland, where they’re either escaped pets that have wandered off, or have been deliberately (and illegally) released by owners who can no longer care for them.
“Turtles are a very tricky pest to catch given their ability to move in and out of waterways and stay underwater for long periods,” Northland Regional Council Biosecurity Manager Don McKenzie says.
Biosecurity Officer Ashlee Lawrence with the Northland Regional Council’s prototype turtle trap at Hikurangi’s Lake Waro.
While difficult to accurately estimate how many turtles are now in the wild here, he says local reports and sightings of them – especially red-eared slider turtles, officially classed as one of the world’s top 100 most invasive species – have been noticeably increasing.
“Whereas a few years ago we probably wouldn’t have received any sightings at all, it’s not uncommon for us to receive several a year now.”
In a bid to tackle the problem, council biosecurity staff had recently built – and been testing – a homemade turtle trap based on an American design.
Council Chairman Bill Shepherd says he’s impressed with the practical simplicity of the roughly metre-wide trap, put together in just a few hours and at little cost using a combination of PVC piping, mesh and popular children’s toy swimming pool noodles.
Chairman Shepherd says a bait tower in the middle of the floating trap is designed to lure in turtles, which use the mesh and the trap’s outer ring of pool noodles to climb over the pipes to reach it. However, once inside, the pipe surface is too smooth for them to climb out again and the mesh hanging beneath means they can’t dive under either.
Mr McKenzie says while escaped turtle’s eggs are very unlikely to be viable in Northland’s current environment, the wild turtle population is continuously supplemented through escapes or illegal pet releases.
“While turtles are quite long-lived in their natural environment, they aren’t likely to live beyond several years in the wild here as they typically eventually succumb to shell infections that require medical treatment.”
“However, given the population is continuously being boosted by escapes/releases we don’t think this will be reducing overall numbers greatly.”
He says in the meantime, those turtles are unfortunately free to predate on nestlings of ground birds, skinks, frogs, fish and vegetation.
Mr McKenzie says it’s usually fairly easy to tell the difference between truly wild and tame turtles. “While all turtles will try move away from humans, tame turtles are very calm and generally will not try bite, scratch or kick when handled.”
He says turtles must be kept in a secure area at all times to prevent accidental escapes and if someone can no longer care for a turtle, releasing it into a nearby stream is not an acceptable – or legal – solution, with offenders risking prosecution.
Mr McKenzie says at this stage, the council is still testing the prototype trap and will wait until the next turtle sighting is reported to deploy it for real. In the meantime, staff would continue to make minor adjustments to the trap’s design to better suit Northland conditions.
Mr McKenzie says over the past two years, four live turtles had been handed in to biosecurity staff in Northland. The fate of any turtles handed in or caught depended on their condition at the time.
“If tame, we first endeavour to find its owner, who is then sent a formal ‘Notice of Direction’ to contain their pet more securely or alternatively, we rehome the animal to the best of our ability. However, where the turtle is obviously feral and no home is available, it’s humanely euthanised.”
He says people encountering what they think is a turtle on the loose should contact council biosecurity staff as soon as possible on (0800) 002 004.
Meanwhile, he says general information about a wide variety of land and water-based pests – including red-eared slider turtles – is available online via www.nrc.govt.nz/pestcontrolhub