Study says killer whales are either temperate or tropical and more should be done to protect Bremer Bay orcas

A university study which investigated more than 1300 killer whale sightings over the last 40 years has concluded more must be done to protect orca populations, including around their habitat in the Bremer Sub-Basin. The Flinders University paper, which was published in July’s Ecology and Evolution, also suggested there are two ecologically distinct groups — temperate and tropical — with those from Bremer Bay preferring temperate waters. Lead author and PhD student Marissa Hutchings said the Bremer Bay contingent remained at-risk, despite congregating in the Bremer Marine Park which covers 4472sqkm offshore from the Fitzgerald River National Park, halfway between Albany and Esperance. “The marine park really needs to be rezoned because part of it is still open to exploitative activity and the main hotspots in the canyon are not protected at all,” she said. “The key issues are around oil and gas drilling, and commercial fishing.” The canyon, 70km offshore from Bremer Bay, is a series of deepwater rifts which are home to an extraordinary range of marine life, including killer whales. Ms Hutchings said there were between 200-300 killer whales which come regularly to the Bremer Sub-Basin and, though based in Adelaide, after she spent around six weeks in the area as part of her research. “They are the largest aggregation in Australia and also the most predictable,” she said. “They return to their habitat every season. “This work greatly increases our understanding of killer whales in Australian waters and identifies areas of biological importance for management and monitoring. “Not only do we now have a nationwide picture, but our findings also support the idea that at least two ecologically distinct forms of killer whales exist in Australia — a temperate and a tropical form.” Ms Hutchings said the research effort for the paper had been a collective approach. She thanked two of her co-authors, Rebecca Wellard from Project Orca and marine researcher John Totterell, from the Cetacean Research Centre, who has been investigating the Bremer Sub-Basin whales for many years. She said the whale-watching charter boats had also filtered through invaluable information but wrote in her submission that more data was needed. “The study showcases the utility of citizen science data, and informs the conservation of this species, which is still considered data deficient and remains to be adequately protected under Australian Government legislation,” she wrote. She has already been working on her next study which looks at population dynamics and again includes the Bremer whales.

Study says killer whales are either temperate or tropical and more should be done to protect Bremer Bay orcas

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