A DEAKIN University researcher has found the ocean off southern Australia is among the most productive food areas in the world for endangered pygmy blue whales.
However PhD student Margie Morrice said the abundance of krill, the whales’ main food source, varied markedly across the years, probably due to climate change factors.
Ms Morrice’s study aimed to quantify the availability of krill, and their habitat factors in a representative area of the Bonney Upwelling area.
The Bonney Up-welling area extends from Ceduna in South Australia to Portland and is where cold nutrient-rich waters rise up from the ocean floor from November to May, sustaining a rich ecosystem that includes krill.
“That’s why the blue whales return here each year, but they do have to search for a while across the shelf looking for food,” Ms Morrice said.
She found a combination of habitat factors influenced the abundance and variability of krill, with surface wind patterns and upwelling strength being of particular importance.
Her study found krill species were off south-west Victoria year-round but were most prevalent in summer.
The whales appeared to show a preference for tightly packed schools but there was some uncertainty over whether they preferred surface schools or feed at depth.
Ms Morrice said the study findings could be used to influence management practices across whale feeding grounds and to mitigate any impact of human activity.
“We need to find ways to minimise pressure on these zones.
“On a personal level we can all do our bit by doing little things like turning off lights to reduce the effects of climate change,” Ms Morrice said.
Her blue whale study is part of the Indo Pacific Blue Whale Research Consortium that is looking at the wider challenges facing the species.
“They are long-range foragers and travel thousands of kilometres.
“Somehow they know how to hit the right spot to find their prey,” she said.
Ms Morrice took 11 years to complete her PhD, with her studies interrupted by marriage and raising a family.
However whales remained an abiding passion and she moved to Warrnambool to pursue her studies of the blue whale.