"Ten per cent is not sustainable except during recovery from population suppression," he said. "In nature, humpbacks live for about 50 to 80 years meaning that a two per cent replacement rate each year approximates a stable population." There are now about 30,000 humpbacks travelling past WA each year. Population increase of 10 per cent means that this year there will be 3000 more than last year. Humpbacks spend the southern winter in WA's semi-tropical waters and head to the Antarctic during the southern summer. Mr Carbon said when a population has been "suppressed" such as through commercial whaling, the population recovery goes into "overshoot" when the suppression is removed.

"This is what is happening with humpbacks. The population will overshoot the capacity of the environment to support. "When the population exceeds the capacity of the environment to support it, an acclimation of numbers will occur. "Overshoot and acclimation occur all the time in nature as can be seen with land equivalents like kangaroos and rabbits. "Either humpback birth rates will suddenly fall soon or death rates will spike, or both." Mr Carbon estimates that there are 80,000 to 100,000 humpback whales in the world, similar numbers to that before commercial whaling.

"The amazing success of humpback whale recovery shows the great resilience of the species," he said. Mr Carbon said whilst there was "great reason to rejoice the recovery of humpback whale populations the world is now in unrecognised territory". "It may well be that our society faces the need to accept that unless humpback birth rates drop rapidly, the inevitable consequence is an escalation of whale deaths." However he expects nature to resolve the issue over time. Mr Carbon said it would be worth investigating why the humpback population had flourished since Australian whaling stopped - while other species had not.

Wilderness Society WA state director Jenita Enevoldsen said the true population of humpback whales was not known and a lot of research was needed to clarify this. She said changes in status of animals should not occur until the evidence supported doing so. John Woodbury, owner and operator of Albany Whale Tours said while he had seen an increased number of humpbacks this season, he had not seen signs of overpopulation. "We haven't come across dead whales," he said. "One indicator of an overstocked species is they don't make it to maturity and the weakened animals will become even weaker and die.

"I feel they are still in good shape." Mr Woodbury said he had noticed slight changes in migratory patterns, with whales passing by further from land and a reduction on the number of Southern Right Whales, "but they are like that, they flux a lot from one season to the next." Mr Carbon's comments follow research by Murdoch University and the Department of parks and Wildlife looking at reasons behind an increased number of stranded whales on WA beaches. It was based on figures showing there were 46 stranded humpback whales in WA in 2009 compared to 16 in 2010. A Department of Parks and Wildlife spokeswoman said the department was aware of the increase in the humpback whale population.

"The increase in humpback mortalities on the west coast has been documented in a published peer-reviewed scientific paper," she said. "The hunting of the humpback whale population that migrates annually along the WA coast ceased in 1963, when the population was depleted to less than 500 individuals. Today the west coast humpback population is estimated at 30,000-34,000. "This figure is reviewed annually by the International Whaling Commission." The spokeswoman acknowledged that the rate of population increase had been approximately 10 per cent per annum. She said there had been an increase in whale carcasses off the WA coast.

"Mortalities are a natural process and over time nature balances the population of any species according to the carrying capacity of the environment in which they live. This year, the Department of Parks and Wildlife has dealt with nine whale carcasses across the state, the majority have been calves and this figure has decreased since 2009." Officers from the department monitor the west coast humpback population and respond to incidents as they occur and also works closely with scientists in an effort to better understand the biology of humpback whales and investigate the factors contributing to the mortalities. Humpback whales are specially protected fauna under the WA Wildlife Conservation Act 1950. They are also protected under Commonwealth legislation. Follow WAtoday on Twitter