Why whale numbers are both a surprise and concern
WHALES must ultimately become victims of their own success as an explosion of numbers has scientists worried about the sustainability of current growth rates.
About 30,000 whales will pass the Sunshine Coast by the end of this migration season, an 11% jump on 2015 figures and a rate of growth that has been consistent for the past 35 years.
University of Queensland whale researcher Associate Professor Michael Noad says the population is doubling every seven years which has caused both surprise and concern.
Whales were now back to their natural population levels before they were all but wiped out by the whaling industry.
However, the continued rapid rate of growth has scientists hopeful it would settle at between 40,000 and 50,000 or when their environment's carrying capacity was reached or exceeded.
Ultimately if that doesn't occur, Prof Noad said, the end result would be mass mortality.
"Their recovery is extraordinarily good news," he said. "We just hope the whales can sort themselves out.
"We may see more dead wash up. Their food source will be the limiting factor. They eat krill but we are not sure how much is in the Antarctic."
Prof Noad has been part of a research team that monitored whales and recorded their sounds off the Sunshine Coast for 11 years.
He said he had seen dead whales off the coast here with a white pointer chomping at the carcass.
"That's a good thing," he said. "A white pointer with a full belly is zero risk.
"There are interesting ecological implications.
"The carcasses would put extra nutrients into the system. Lots of things can eat whales (carcasses)."
The Tangalooma whaling station on Moreton Island was the biggest in the South Pacific from 1952 to 1961, processing 600-700 whales annually.
By the end of its life it was running out of the cetaceans processing only a few in 1962 before it was closed.
Prof Noad said the problem though was not at the Queensland end but in the Antarctic where the soviets slaughter 22,000 whales including mothers and babies in one two-year period while reporting it had only taken 400.
"It was a great tragedy that wasn't revealed until the collapse of the Soviet Union," he said.
"It took to the 1990s to realise what had happened."
The whale population had collapsed to just a few hundred.
"When we stopped killing them the humpbacks recovered," Prof Noad said.
"The blue and fin whales though remain comparatively few. Why they haven't recovered is still a mystery."
Prof Noad will be back on the Sunshine Coast with his fellow researcher Dr Rebecca Dunlop to collect data from an acoustic recorder they have positioned two kilometres off Peregian to record whale songs.