Humpback whale numbers growing too fast

Once hunted to near extinction, Australia's humpback whale population has now exploded and could soon become unsustainable.

The population has grown from just a few hundred to more than 25,000 since commercial whaling was banned in 1962, a University of Queensland study has found.

Associate Professor Michael Noad says the whale population was growing by about 10 per cent every year and if that rate continues, it could be unsustainable by 2021.

Scientists had expected the growth rate to slow as whale numbers stabilised.

"That hasn't happened," Dr Noad said.

"Whale numbers are still steaming ahead at a tremendous rate - the population is virtually doubling every seven years.

"If that keeps going, by 2022 there will be 50,000 whales - that's a lot of whales.

"They could overshoot the carrying capacity of the environment and we could see a big decline in the population."

Dr Noad said it could lead to beach strandings and we could see a lot of thin and dying whales.

If the population does oscillate, it would probably be a natural process and there would be very little we can do about it, he said.

He said there could be serious consequences for the whale watching industry, which is worth more than a $100 million to the Qld economy each year.