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Cane toads infiltrate other states

KERRY O'BRIEN: It was a regrettable day in Queensland, and, for that matter, Australia's history.

The day in June 1935, when 101 cane toads arrived at Gordonvale, near Cairns, from Hawaii.

They were meant to be a cheap and effective method of controlling sugar cane pests, but they weren't content to restrict themselves to north Queensland's cane fields.

They've spread south into NSW and west into the Northern Territory, poisoning Australian wildlife as they go.

Now, they're in Kakadu National Park and they're expected to hit Darwin as early as next wet season.

So far, science has failed to curb the cane toad explosion.

And, as Murray McLaughlin reports from Darwin, they'll have crossed into WA long before a new attempt at biological control is developed.

MURRAY McLAUGHLIN: This sound brings dread to Northern Territorians.

It's the mating call of the male cane toad and it's rung out across the Territory since the cane toad crossed the border from Queensland nine years ago.

Scientists fear the consequences of its invasion.

PROFESSOR GORDON GRIGG, ZOOLOGY, UNIVERSITY OF QUEENSLAND: I think I find it hard to believe that this huge, numerous, introduced species could go into the areas that they've invaded and are continuing to invade without having some very large change on the local ecosystems.

MURRAY McLAUGHLIN: Ian Morris is a leader of Frog Watch in the NT.

Frog Watch is a network of volunteers who log the presence and behaviour of frog colonies.

Tonight, Ian Morris is marking the proliferation of cane toads in the township of Mataranka on the Stuart Highway 400km south of Darwin.

Cane toads landed here just two wet seasons ago.

Since they have hit the tropical zone and prospered in better and better conditions, their rate of progress has been exponential.

IAN MORRIS, FROG WATCH: They almost doubled their mode of progression this wet season compared with last wet season as they progressed north into Arnhem Land and up the Katherine River catchment and so on.

So, it's more than about 100km a year at the moment.

MURRAY McLAUGHLIN: They've now crossed into Kakadu National Park in the far north of Australia, a jewel in Australia's list of World Heritage sites.

They're expected to thrive here and their impact on native species is most causing concern among the country's scientists.

Cane toads eat a wide variety of prey, compete for food and have highly toxic chemical defences.

An assessment last year by government scientists noted serious concern that the status of Kakadu National Park could be diminished.

IAN MORRIS: They're going to be visible all around Kakadu, all around the resorts.

They'll be around the lawns and the lights at night time.

And there's not a lot we can do about that.

So yes, in a sense, I guess they will be the first feral species that are in people's faces in Kakadu.

MURRAY McLAUGHLIN: Predictions about the impact of the cane toad among native species in Kakadu National Park are still only guesswork.

There's been little monitoring to enable reliable comparisons before and after the cane toad sweeps through.

Only last year were the first data collected from stations in Kakadu which record the presence of native frogs in the park.

Their distinctive sounds are being tracked because frogs are expected to be most at risk from the cane toad.

But the scientist in charge of the experiment wishes he'd been here years before.

PROFESSOR GORDON GRIGG: The overall thrust of research on cane toads has been too little too late.

I think it's been confounded by dispute about whether or not cane toads are really causing a problem, anyway.

MURRAY McLAUGHLIN: That dispute derives largely from the policy position of Bill Freeland, head of the Parks and Wildlife Commission of the Northern Territory.

He's tended to dismiss any need to intervene scientifically in the march of the cane toad.

QUANTUM EXCERPT: From there, the total conquest of Northern Australia is but a hop, step and a jump.

BILL FREELAND, NT PARKS & WILDLIFE: We've studied it for many years now and so have other people.

As yet, nothing has gone extinct in Queensland or in the Northern Territory.

And that suggests to me it's not a huge, huge problem.

JEAN-MARC HERO, GRIFFITHS UNIVERSITY: Well, I think it's a very unscientific way of addressing the problem.

There are not only the scientific impacts on other fauna, but also the human impacts and I think both of these have been severely neglected.

One thing we could do is certainly even educate people prior to their arrival so they know what to expect.

And certainly the indigenous people in the NT and Arnhem Land are very concerned about the potential impact on things like bush tucker.

MURRAY McLAUGHLIN: In the two years since cane toads invaded Mataranka, locals have reported dead turtles and small freshwater crocodiles floating with a cane toad in their jaws in the nearby Roper River.

Traditional bush tucker has also diminished.

VICTOR GROVES: Catfish are dying away from it and also a couple of them water goanna.

They're gone, too.

MURRAY McLAUGHLIN: In spite of the best efforts of the CSIRO, it will be a long time before the cane toad's gone.

Scientists have identified a lethal virus in Venezuela, where cane toads are a native species.

But the virus couldn't be released here, because it also kills Australian native frogs.

Now, the Federal Government's looking at another biological solution.

These cane toads were rounded up in Brisbane last week and they'll be used by scientists to isolate a gene critical to the cane toad's development.

DR TONY ROBINSON, CSIRO: During that time when a tadpole changes into an adult, there's huge changes going on in the body of the animal and it's producing a whole lot of new proteins.

And we think they could be targets for --

to arrest their development.

MURRAY McLAUGHLIN: The Brisbane cane toads are now resident at a specially humidified laboratory in Canberra.

DR TONY ROBINSON: So, they're quite dry to touch, aren't they -- they're not wet?

RESEARCH ASSISTANT: They're not slimy.

MURRAY McLAUGHLIN: If the CSIRO can identify the appropriate gene, it'd be distributed through a natural virus to arrest the cane toad's development before they got to their reproductive stage.

But this is high-flying science.

And even if the CSIRO is successful, it will be several years before it could be applied in the field.

By then, cane toads will have moved over the border into WA and have been long-ensconced in Darwin.

IAN MORRIS: It'll probably be within about 12 months that Darwin is invaded.

It will have an effect on every person living in Darwin one way or another.

Life as we knew it is going to change, there's little doubt about that.



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