Rat-pocalypse! Skincrawling reason why 'millions and millions' of starving 'cannibal rats' are descending on this picturesque Aussie town in Far North Queensland

A fishing town in far north Queensland has been overrun by cannibal rats with thousands of their bodies seen rotting on beaches every day.

A rat 'plague' has afflicted parts of the Sunshine State for several months but locals in Karumba, on the Gulf of Carpentaria, say things have drastically worsened this week.

Footage shows bloated rat bodies clogging beaches around the small town and thousands of the rodents swimming in the river at night.

'They're really getting out of control,' one fisherman told ABC North Queensland.

'There's a stench along the riverbed. Last night, with the moonlight, the river was truly alive with them.' 

Another local said: 'We saw them dead or alive, but exhausted, in the water and on the shoreline. [When we returned four days later], they were running on the sand'.

However, the problem hasn't been restricted to the coast with several Outback towns struggling to control the rats and mice.

One resident described 'millions and millions of rats on the road' outside Cloncurry, some 450km south of Karumba.

'Every dead rat on the road had another three or four rats eating it. There was about a metre between dead rats. It was insane,' he said.

'You drive between McKinlay and Winton at night and the ground is crawling with rats. They are that thick, they're eating their own straight after they're squished on the road,' another said.

University of Sydney ecology professor Mathew Crowther explained a perfect storm of wet conditions and abundant crops has led to a massive rise in rodent populations.

'Most rodents eat vegetation, seeds, they'll eat insects and they'll eat everything at plague proportions,' he told Yahoo News.

'Our animals are adapted because they have these really variable rainfall patterns and animals concurrent with that are quite successful, they can respond quickly.'

He added the sheer number of rats in Karumba could be driving them to swim to nearby sandbars in search of food.

However, they wouldn't have the energy to swim back and drown as a result.

Prof Crowther explained the dwindling supply of food for the rats will eventually see the populations fall back down to pre-plague levels.

'They tend to get really high numbers but then they start crashing because they've eaten their food sources out,' he said.