Canberra, May 10 : Australian researchers have warned warming oceans are putting pressure on the food supply of blue whales after observing thin individuals off the country’s south coast.
The Blue Whale Study (BWS) undertakes aerial surveys of the large marine mammals feeding in waters between South Australia and western Victoria every year before they migrate north to breed.
Peter Gill, a pioneer of blue whale research in Australian waters and chief executive of the BWS, said the most recent survey spotted more individual whales than in previous years but raised concerns about their health.
“We’ve seen a number of skinny blue whales, researchers on the west coast have seen skinny blue whales, and that’s a bad sign,” he was quoted by the Australian Broadcasting Corporation on Wednesday.
“That means probably they’re not getting enough food at some stage in their life cycle.”
Because of their immense size, blue whales must feed all year round to maintain a healthy weight, which can exceed 200 tonnes.
Gill identified breeding grounds off the coast of Indonesia as a potential site where food is in short supply.
“There have been signs that those waters are warming quite quickly in the past few years, and that’s bad news for krill, which likes cold water,” he said.
Because of their large, consistent migratory patterns and other habits, the health of blue whales is considered an indicator of the health of the world’s oceans.
Wildlife scientist Vanessa Pirotta said surveys across multiple years could help boost the understanding of what environmental changes the whales are facing.
“We can use these animals potentially as a canary in the coal mine to learn about changes in the ocean that we’re not yet aware of,” she said.
