By Phil Mercer
BBC News, Sydney
Grey nurse shark numbers declined rapidly in the 50s, 60s and 70s
They are known affectionately as the "Labradors of the ocean", but grey nurse sharks are facing a fight for survival in Australia.
It is estimated there are fewer than 500 of these docile creatures left in Australian waters. Most live off the east coast.
Despite its fearsome appearance, the grey nurse (Carcharias taurus) is not a man-eater.
Environmentalists have said their numbers continue to fall despite the grey nurse shark being a protected species, which it has been since 1984.
Blame is laid at the feet - or rather the hooks - of fishermen who inadvertently catch them.
Conservationists and scientists have held what they have described as "crisis talks" in Sydney.
They are now threatening legal action to force the country's political leaders to do more.
"The grey nurse shark situation is critical," warned Ian Cohen, a Green member of the New South Wales state parliament.
"We're likely to see the demise of this species on the east coast of Australia in the next 10 to 15 years. It is really a desperate situation when we look at the continued threat through both recreational and professional fishing practices," he told the BBC.
Mr Cohen accuses the New South Wales state government of caring more about retaining power than the environment.
Fishing hooks are a major hazard for the grey nurse sharks
"Leading up to an election next year [the government] has an eye on the voting power of the recreational fishing lobby," he said.
There are 16 key grey nurse shark habitats dotted along the coast of New South Wales, from the tourist haven at Byron Bay south to the rugged beauty of Montague Island.
Wildlife campaigners want the authorities to establish a 1.5km-wide "sanctuary zone" around these critical aggregation sites. They are demanding a complete ban on fishing, arguing that there would be plenty of alternative areas to satisfy fishermen and women.
The grey nurse is listed as an endangered species under Australian law.
Conservationists have insisted that the state and federal governments have failed to fulfil their legal obligations.
Nicola Beynon, from Humane Society International, said protecting sensitive habitats could not happen soon enough: "This is the time when we have a chance of turning around the specie's fortunes on the east coast and if we don't seize it now then extinction's going to be inevitable.
She added: "The grey nurse shark is a top predator in the ocean, so it's very important in terms of the well-being of coastal marine eco-systems.
"It's not just a case of saving it for its own sake; we need to save sharks for the role that they play in keeping the oceans healthy. In effect, protecting the grey nurse shark is also beneficial to the fishing industry because it keeps the ocean that they depend on healthy and productive."
If environmentalists were hoping for a positive response from the New South Wales government they have been disappointed.
The State Minister for Primary Industries, Ian Macdonald, accused his critics of scare-mongering.
"I think that they're talking a lot of nonsense and exaggerating the situation rather dramatically," he told Australian radio.
The minister said he was considering introducing shark sanctuaries at five grey nurse sites and that he was not fazed by the threat of legal action.
The adults will reach up to four metres in length
"Our view is we have the measures in place and it would be a complete waste of money by the green groups to be running off to the courts," he said.
"We are spending a lot of money on the breeding programme. If we're able to complete this successfully, it will have a dramatic impact on the survival of the shark, not only in Australia but overseas."
Australia's federal government also said it was doing all it could to protect this relatively placid and ragged-tooth shark.