Turtle researchers say putting artificial islands in the Murray River is one way to save dwindling turtle populations.

The man-made island strategy is one of a handful of ideas recently put forward by a team at Western Sydney University, led by Ricky Spencer and the Foundation for National Parks and Wildlife.

The university has been working with the not-for-profit foundation for the past few years to research why turtle species in the Murray River, including the Murray short-necked turtle, eastern long-necked turtle and broad-shelled turtle, are on the decline.

They have recently come up with a number of proposals including fox management techniques, community programs and man-made islands to help save various species of turtles in the Murray River before they become extinct.

The foundation works with the university to help raise funds to trial and implement these strategies.

A species in decline

Foundation chief executive Ian Darbyshire said the Murray River long-necked turtle population had declined by 90 per cent in the past 40 years and was heading to extinction in some parts of Australia.

The Murray River short-necked turtle had declined by more than 70 per cent in the past 40 years.

Dr Spencer said the problem was getting worse.

"Every few years we survey 50-100 sites throughout the Murray River to check on the turtle population and track the numbers … We have worked out that in some areas we are not finding any turtles in an area where they should be or have been previously," he said.

"In South Australia, we are seeing locally extinct populations and we are starting to see it further up the river into New South Wales and Victoria. Something needs to be done now.

"Unfortunately, in Australia we usually have to wait for animals to become endangered before any action is taken and by then it is too late."

Dr Spencer said turtles were an essential part of a river's ecosystem and kept rivers clean.

"We call them the vacuums of the river because they eat a lot of dead things like fish, so they are real scavengers of the river," he said.

"Depending on the species, they eat a lot of algae and plants and that sort of stuff as well.

"So they are the main vertebrate scavengers in the river systems."

An example of an artificial island that could be modified to target nesting turtles. ( Supplied: SPEL Environmental )

Foxes main threat to nests

Mr Darbyshire said there were a number of reasons for turtle population decline, including car accidents and a lack of food sources, but foxes destroying turtle nests were the main threat.

"Foxes are damaging and destroying about 95 per cent of the turtles nests and the problem with that is you have to get rid of all the foxes in an area to actually protect the nests," he said.

Dr Spencer agreed.

"Standard fox control hasn't worked because the main problem is you really have to get rid of all foxes in an area," he said.

"Even if you reduce them by 70 per cent or 90 per cent or more, the one or two foxes that are left in the area can still destroy all the nests.

"The idea is to say, 'Okay, we need to look at techniques that are going to work,' — in some cases fox control will be okay, but in some cases in we need to look for alternatives.

"So we are working with the foundation to bypass the fox."

Dr Ricky Spencer said it's a critical time to save the turtles from extinction ( Supplied: Craig Latta )

An island home

Dr Spencer said he had been discussing the artificial island idea with companies that already created modular islands to see if they could be used for nesting turtles.

"Some have already been created for water quality — so they are foamy islands that you put plants in that absorb nutrients and that sort of thing," he said.

He said the islands tend to be 5-by-5-metre modules that clicked together, so they could vary in size.

"We know the modular islands work and float but we don't know if we can create a modular where turtles can get onto them, and we need to trial that," Dr Spencer said.

"Within these large islands, we could create areas of turf or sand where the turtles and even birds could come up and nest."