Crocodiles up to six metres long are terrorising farmers in Australia's Northern Territory, with one outback property losing 200 cattle in a year. Crocodile numbers have increased dramatically since hunting was banned across tropical northern Australia nearly 30 years ago. Conservationists estimate that the population of wild saltwater crocodiles in the Northern Territory has grown from about 5,000 in the early 1970s, when shooting was outlawed, to 70,000. The species' range extends into Western Australia and northern Queensland. Big saltwater crocodiles are supplementing their normal diet of fish, wallabies, feral pigs and turtles with cattle, horses and dogs. Crocodiles lie in wait before launching themselves at an animal close to the water's edge. One farming family has lost five pet dogs to crocodile attacks. 'Crocs are everywhere,' said Marlee Ranacher, 42, who with her husband Franz, 34, manages 9,000 cattle at Bullo river station, a sprawling cattle ranch covering 1,600 sq km, 400km southwest of Darwin. She said they had lost 200 cattle in the past year to the crocodiles. 'This is one of the last frontiers. There are not many places in the world that have crocodiles as big as the ones around here. When I grew up, a 12ft crocodile was considered big. Now we are regularly seeing 16-footers and some are up to 18ft. At that size they weigh a tonne,' Mrs Ranacher said. The crocodiles are becoming more active as the Northern Territory's wet season approaches and temperatures rise. When the rains come next month, small creeks will turn into raging rivers and billabongs will become huge lakes, enabling the crocodiles to spread out over a much greater area. 'We have a creek close to the house and when it floods the crocodiles come right up to the back gate,' said Mrs Ranacher, who has two young children. The Ranachers have been given a licence by the Northern Territory Parks and Wildlife Commission to trap and shoot 10 large crocodiles. The animal's skins, complete with skull, sell for up to A$15,000 (HK$81,550). The increase in crocodiles has sparked a public debate over whether they should be more extensively culled. 'Whenever there's an attack, there's a public outcry, with people saying, 'Let's get rid of them',' said Dion Wedd, acting curator at the Territory Wildlife Park south of Darwin. 'There are certainly more of them and they are becoming less fearful of boats and the sound of outboard engines. But it all comes down to personal responsibility - if you go swimming in a river and get attacked by a croc, that's your lookout. It's like standing in the middle of a highway and complaining there are too many cars.' Crocodile attacks on humans are rare. The last fatal attack was last October, when a 23-year-old German tourist, Isabel von Jordan, was killed by a 4.5-metre-long saltwater crocodile while taking a midnight dip in a billabong in Kakadu National Park in the Northern Territory.