Human activity 'driving half of world's crocodile species to extinction'

As many as half of the world’s 27 species of crocodilian face being wiped out due to human activity, although the most feared variety, the saltwater crocodile, faces a brighter future, according to a new book by a veteran crocodile researcher.

Land use changes, pollution, culling and feral animal invasions mean that many crocodile species face a “bleak future”, warned Professor Gordon Grigg of the University of Queensland.

The gharial, a distinctive long-nosed species that eats fish, is suffering from the destruction of its habitat in India. Riverside development and dredging of the Ganges is having a huge impact upon the species, as is the indiscriminate use of netting.

The Philippines crocodile and the Chinese alligator, which is almost extinct in the wild despite being intensively farmed for meat and leather, are other species at risk of disappearing over the course of this century, Grigg said.

However, the saltwater and freshwater crocodiles of northern Australia have a brighter outlook, buoyed by the banning of hunting in 1970.

Since the ban, numbers of saltwater crocodiles have significantly increased. “Salties” are the largest living crocodilian on Earth, with some animals reaching seven metres long and weighing 900kg.

“The chances for about half of the 27 species are pretty slim if the trend in human land use continues,” Grigg told Guardian Australia. “Habitat is being destroyed, crocodiles are being caught in nets, feral pigs are eating croc eggs.

“But freshwater crocodiles are quite secure, they’ve never been as despised as saltwater crocodiles. And the American alligators should be OK because they are now protected from hunting and their marshland habitat is probably too wet for agriculture.

“The population of salties got very low in the 1960s and there’s been a dramatic recovery since then. Numbers are approaching historic pre-hunting numbers. I think they are pretty secure unless its decided in the future that we need to go out an exterminate them.”

Grigg, who has written a new book called Biology and Evolution of Crocodylians with Canadian zoologist David Kirshner, said that crocodiles should benefit from climate change trends.

“As aquatic habitats warm up due to climate change, it’ll mean crocodiles can move to habitats further north and south,” he said. “I’d say we can expect salties to come further south in Queensland. A lot of crocodiles won’t survive the human pressure but those that do survive will have more habitat.”

The rebound in saltwater crocodile numbers has led to calls for safari-style hunting of the species to be allowed in the Northern Territory. Some Australian politicians have also voiced support for a more widespread cull to avoid attacks on people.

In May, a Darwin man was repeatedly attacked by a 2.5m-long saltwater crocodile as he kitesurfed on a beach. He poked the animal in the eye and escaped.

Meanwhile, an inquest is currently being held in Darwin to the death of two fishermen due to crocodile attacks in June and August last year. One of the men, Lanh Van Tran, was seized by a 4.6m-long albino saltwater crocodile known locally as Michael Jackson as he attempted to free a snagged fishing line.