AUSTRALIA’S humpback whale (Megaptera novaeangliae) populations have recovered to the point where scientists are recommending the mammal be removed from the threatened species list.
A recent project involving local and international researcher gathered abundance estimates from recent studies to compare against the Environmental Protection and Biodiversity Conservation (EPBC) Act criteria for listing a species as threatened.
They found that humpback whales—which were once hunted to the brink of extinction and are currently listed as vulnerable—do not meet any of these criteria, which include limits for species distribution, population size, rate of decline, and probability of extinction.
Corresponding author Murdoch University Professor Lars Bejder says Australia’s two humpback whale populations have made an amazing recovery over the past 45 years.
“We believe they have recovered so well that they should be considered for down-listing,” Prof Bejder says.
He says even conservative abundance estimates suggest that in 2012 the west coast population had recovered to 19,000 individuals from a population estimated to have been reduced to 270 at the end of the peak whaling era.
“There’s no indication that these populations will go back to anywhere near the numbers they were due to whaling,” Prof Bejder says.
The east and west coast populations have both been increasing at rates of between nine and 10 per cent each year for more than half a decade, Prof Bejder says.
He says, in the face of human-induced pressures such conservation successes are often few and far between.
Threatened Species Scientific Committee (TSSC) chairperson Professor Helene Marsh, whose committee makes recommendations to the Minster for the Environment on such listing changes, says down-listing where a population has recovered is cause for celebration.
But she says a rigorous statutory process must be followed before any change is made.
“We need to be sure that down-listing won’t put the species at risk,” Prof Marsh says.
Even if humpback whales were to be down-listed, they would still be protected under the EPBC Act because of their status as a ‘matter of national significance’ as a migratory cetacean.
Prof Marsh says species at greatest risk will be given first priority but that the humpback whale status is on the TSSC’s agenda.
Prof Bejder says that if the humpback whale were to be down-listed, this could re-prioritise resources to devote to higher-risk marine mammals such as the more solitary blue whale (Balaenoptera musculus), whose populations have yet to rebound.