Gruesome images of adult and juvenile humpback whales along Australia’s east coast with slash and gouge injuries from boat and propeller strikes highlight what experts say is a growing problem, as the population booms 60 years after the ban on whaling.
Missing tail parts, deep red lacerations and shocking injuries to the spine of a whale calf can be clearly seen on the images, gathered by WWF Australia and shared with the Guardian.
One image of fresh and broad cuts on the back of a calf was taken last month in Hervey Bay in Queensland, where many mothers choose to bring their calves for rest and shelter on the long migration down to Antarctica.
The atmosphere on the town’s whale-watching boats is often one of heightened excitement and elation, as the majestic mammals come to the surface, says Isabel Taylor, a senior naturalist with the Pacific Whale Foundation’s whale-watching tours.
Last month, Taylor saw two mothers with calves come to the surface, but all was not well with one pair.
“The others were very surface active and putting on a show, but this other mum and calf were more reserved,” she says.
Clearly visible on the calf’s back were slash marks from a boat propeller. “The mood on the boat changed a bit,” says Taylor.
“We get people from all over the world and some say it’s the best day of their lives. So to have this on the other end of the spectrum was quite profound.”
Another image taken in June by drone off Sydney’s Bondi beach shows a humpback with lacerations and exposed red flesh that appear to have been caused by repeated sweeps of a propeller blade.
An image from 2024 shows a female humpback off the coast of southern New South Wales that has become known as “bladerunner” because of a highly distinctive sequence of deep slashes from a propeller blade on her back and tail thought to have been sustained more than 20 years ago.
“These images really bring home the physical and direct impact we’re having on these animals, especially on animals that size,” says Dr Raphael Mayaud, a marine ecologist at Griffith University and a member of an expert group advising the International Whaling Commission (IWC) on vessel strikes.
Rebecca Dunlop, an associate professor and humpback expert at the University of Queensland, says most of the images showed injuries to the back and rear of the whales, “suggesting they are surfacing as the boat propeller goes past and over their back”.
“When migrating humpbacks travel and surface like clockwork they don’t seem to be able to change their dive and travel behaviour to avoid an intercept pathway – this could be due to a boat approaching the intercept point at speed where they just don’t have the time to make an avoidance decision,” Dunlop says
Conservation success story
The IWC banned humpback whaling in the southern hemisphere in 1963 – after numbers had already crashed.
Soviet whalers continued to hunt them in the Southern Ocean until the early 1970s. Estimates from the 1960s put their numbers off the east coast of Australia at less than 300.
But as the threat of the harpoon was progressively removed, the population rebounded. One study based on observations of whales suggested that by 2004 the east coast humpbacks numbered 7,800.
It is seen by many conservationists as one of the planet’s great wildlife recovery stories.
By 2015, their numbers had more than trebled to 25,500. Estimates now suggest between 40,000 and 50,000 whales are migrating up and down the coast each year. Some modelling has suggested numbers will peak and plateau this year.
Dunlop and Mayaud both observe that, as populations have increased alongside the rise in popularity of boating and water recreation, the numbers of vessel strikes have also likely increased.
One in 10 Australians have a boat licence and of the more than 970,000 registered boats, more than half a million are in Queensland and New South Wales.
But it is difficult to know how many collisions there are with both large and smaller boats, experts say.
The IWC says that globally, “most collisions go unseen and unreported”. On Friday, it passed a resolution to work with all parties around the world to reduce “vessel strikes” which, the meeting agreed, was a “priority concern” for the commission.
Chris Johnson, the WWF’s global lead on initiatives to protect whales, who was at the meeting, says it is an important step for the IWC.
“Humpbacks have been one of the great conservation success stories. But along Australia’s humpback highway, there’s growing risk for them to be hit by vessels,” he says.
“Those strikes [in the images] would have been incredibly painful. We can see the evidence, but we have a black hole of information.”
Experts say cutting speed limits for all vessels moving along migration routes, and making boats and ships more aware of the riskiest places and times of the year, would help.
In California, for example, Johnson says shipping companies compete with each other to win high grades on public scorecards that assess how well they stick to speed limits during high-risk periods for whale strikes.
In San Francisco Bay, AI-assisted whale spotting cameras are being trialled to give captains more notice about whales in their path.
While Australian law in theory requires that collisions with protected species like humpbacks be reported, Mayaud says most are either undetected or are never documented.
“The big thing is that a strike doesn’t have to kill a whale to have a serious impact,” he says.
“If a whale loses part of its fluke [tail] it may still survive, but swimming is likely to become less efficient and more energetically costly. That can then have knock-on effects on things like migration, feeding, body condition and potentially reproduction.
“There’s also the immediate trauma – the pain, blood loss, infection – and then the possibility the animal is carrying the effects of that injury for years afterwards.
“So I think the welfare issue is really about both the initial injury and the longer-term energetic and physical consequences for animals that survive.”
