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The sudden appearance of a pair of rare southern right whales in the middle of a shipping lane in Port Botany and in the shadow of the nation’s busiest airport sparked both excitement and an emergency response from experts and authorities, who swung into action to protect them from a gauntlet of modern threats.
The world has not always been so kind to southern right whales, so named because they were the “right” species to hunt back in the whaling days.
Southern rights typically swim at less than 10 kilometres an hour, slower than other targeted species. When harpooned they floated rather than sank. They provided more oil than other species and their bones were fine and flexible, perfect for the fabrication of everyday items like umbrella ribs and riding crops.
By the time commercial whaling was abandoned – as late as 1978 in Australia – it is estimated there were between 1500 and 5000 humpbacks left, but as few as 300 southern rights. Only the blue whale suffered a greater population decline. Worse, while humpbacks calf every two to three years, southern rights do so only every three to four years. The interval stretches when conditions are poor. The humpback population has made an extraordinary comeback, but southern rights have not.
All this helps explain the excitement with which Dr Vanessa Pirotta greeted the arrival of the mother and calf in Botany Bay on Monday afternoon.
“We don’t see them often, this species… we don’t expect to see huge numbers of them, so when we see them, we know that it’s a big deal, figuratively and literally,” she said.
Even better, they appeared to be in good health after a season feeding on krill in the southern oceans.
So rare are the animals that the survival of this mother and calf alone could have an impact on the broader population, says Pirotta, a marine biologist at Macquarie University who specialises in the study of whales. “If we lose a productive female of a very fragmented population that could have population-level impact,” she says.
Botany Bay, also known by its Indigenous name Gamay, is much cleaner than a few decades ago, with the restoration of oysters and sea grass, and reduced pollution.
Yet threats remain. On Monday afternoon, Pirotta held her breath as the mother unwittingly guided her calf into a shipping lane and then sank beneath the surface as a cargo ship approached.
“I was holding my breath, she held her breath, and she was just obviously sitting there. And then after the ship passed, she rose up. It was almost like she was waiting for it,” she said.
The pair could not have known that the humans who once hunted their kind were now watching over them. A National Parks vessel and Gamay Rangers – an Indigenous ranger group based in La Perouse – kept a weather eye on the pair to protect them from collision in the busy waterway.
Shipping strikes are one of the key threats to the estimated 10,000 to 15,000 southern rights that now survive, but not the only one. Climate change is shrinking Antarctic ice coverage, which in turn is reducing the amount of krill upon which the whales feed.
The krill population is also falling because it is being harvested for use as dog food and fish oil supplements. Whales are at risk of entanglement in so-called ghost nets abandoned by deep-sea trawlers, and when they swim up the Australian coast they must navigate the threat of shark nets.
By Tuesday morning, the pair had moved on to Bondi Beach. Pirotta expects the mother may spend some time off the NSW coast, which marks the northern end of the animal’s annual migration, suckling her calf in the warm shallow waters, before returning to the deep south.
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