Humpback whales have been spotted in a Kakadu river. So in a fight with a crocodile, who would win?



Northern Territory Government

Vanessa Pirotta, Macquarie University

In recent months, three humpback whales were spotted in the East Alligator River in the Northern Territory’s Kakadu National Park. Contrary to its name, the river is full of not alligators but crocodiles. And its shallow waters are no place for a whale the size of a bus.

It was the first time humpback whales had been recorded in the river, and the story made international headlines. In recent days, one whale was spotted near the mouth of the river and scientists are watching it closely.

The whales’ strange detour threw up many questions. How did they end up in the river? What would they eat? Would they get stuck on the muddy river bank?

And of course, there was one big question I was repeatedly asked: in an encounter between a crocodile and a humpback whale, which animal would win?

A crocodile partially submerged in a river
The whales swam into a crocodile-infested river.
Dean Lewins/AAP

Scientists double-take

The humpback whales were first spotted in September this year by marine ecologist Jason Fowler and fellow scientists, during a fishing trip. Fowler told the ABC:

I noticed a big spout, a big blow on the horizon and I thought that’s a big dolphin … We were madly arguing with each other about what we were actually seeing. After four hours of raging debate we agreed we were looking at humpback whales in a river.

The whales had swum about 20 kilometres upstream. Fowler photographed the humpback whales’ dorsal fins as evidence, and reported the unusual sighting to authorities and scientists.

Thankfully, two whales returned to sea on their own, leaving just one in need of help. There was concern it might become stranded in the shallow, murky tidal waters. If this happened, it might be attacked by crocodiles – more on this in a minute.




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Experts considered a variety of tactics to encourage the whale back out to sea. These included physical barriers such as nets or boats, and playing the sounds of killer whales – known predators of humpback whales.

But none of these these options was needed. After 17 days, the last whale swam back to sea on its own.

The whale that spent two weeks in the river has recently returned and been spotted swimming around the mouth of the river. It appears to have lost weight – most likely the result of migration. It is now being monitored nearby in Van Diemen Gulf.

Questions are now being raised about the health of the animal, and why it has not headed south for Antarctic feedings waters.

A humpback whale that spent two weeks in the East Alligator River has recently been spotted nearby.
Dr Carol Palmer

So why were whales in the river?

The whales are part of Australia’s west coast humpback whale population, which each year travels from cold feeding waters off Antarctica to warm waters in the Kimberley to breed.

There are various theories as to why they swam into the East Alligator River. Humpback whales are extremely curious, and may have entered the river to explore the area.

Alternatively, they may have made a navigation error – also the possible reason behind September’s mass stranding of pilot whales in Tasmania.

And the big question – what about the crocs?

Long-term, a humpback whale’s chances of surviving in the East Alligator River are slim. The lower salinity level may cause them skin problems, and they may become stranded in the shallow waters – unable to move off the muddy bank. Here the animal might die from overheating, or its organs may be crushed by the weight of its body. Or, of course, the whale may be attacked by crocodiles.

In this case, my bet would be on the whale – if it was in relatively good condition and could swim well. Humpback whales are incredible powerful creatures. One flick of their large tail would often be enough to send a crocodile away.




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If a croc bit a whale, their teeth would likely penetrate the whale’s skin and thick blubber. But it would take a lot more to do serious harm. Whale skin has been shown to heal after traumatic events, including the case of a humpback whale cut by a boat propeller in Sydney 20 years ago. Dubbed Bladerunner, it survived but still bears deep scars.

Humpback whales are very large and powerful. One flick of their tail could send a crocodile away.
Dr Vanessa Pirotta

What next?

The whale sighting continues to fascinate experts. Scientists are hoping to take poo samples from the whale in Van Diemen Gulf, and could also collect whale snot to learn more about its health. However, the best case scenario would be to see the whale swim willingly to offshore waters.

This unusual tale will no doubt go down in Australian whale history. If nothing else, it reminds us of the vulnerability – and resilience – of these marine giants.


The author would like to thank Northern Territory Government whale expert Dr Carol Palmer for her assistance with this article.The Conversation

Vanessa Pirotta, Wildlife scientist, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Staying safe in crocodile country: culling isn’t the answer


Adam Britton, Charles Darwin University

The killing of tourist Cindy Waldron by a saltwater crocodile while swimming north of Cairns on Sunday has reignited the debate about how to keep people safe from crocs. Federal MP Bob Katter has called for a bigger crocodile cull, although the Queensland government has once again ruled this out. There are very good reasons for this decision.

The evidence suggests that calls for complete deregulation of croc hunting are based on flawed arguments. The easiest way to keep people safe is to make sure they understand the risks.

What have we been doing about crocodiles?

Crocodile populations have been managed in northern Australia since the early 1970s. Before that, it was open season: three decades of hunting wiped out 95% of wild crocodiles, although getting them all proved impossible.

Many hunters grew to respect these unequivocally Australian “beasts”, supporting their subsequent protection. Yet their numbers bounced back much faster than anyone expected. Questions were soon being asked about the wisdom of allowing their recovery.

Sub-adult saltwater crocodile basking on a tidal mud bank, a popular sight for the many tourists who visit northern Australia each year.
Adam Britton

Recognising the value of crocodiles to people and ecosystem health, the Northern Territory government changed tack. Crocs became tourism icons, their eggs and skins were harvested sustainably to create local jobs and a fledgling industry, and safety issues were managed by the targeted removal of “problem” crocodiles, alongside visible media campaigns about staying safe. Despite differences between states and territory, the same basic approach is still used.

Has it been effective in saving lives? The first subsequent recorded fatal attack in Queensland happened in 1975, when Peter Reimers was killed while wading in a creek near Mission River. This was only a year after the crocodile population had been protected because it was on the verge of disappearing. Three decades of unregulated hunting hadn’t saved Reimers’ life.

The latest statistics as compiled by CrocBITE show 112 attacks between 1971 and May 2016, 33 (30%) of them fatal. That’s an average of 2.5 non-fatal attacks per year and 0.7 fatal attacks per year across Western Australia, the Northern Territory and Queensland. The rate has increased slightly over the past decade, but crocodile attacks remain extremely rare in Australia.

Number of reported saltwater crocodile attacks per country (April 2007 to April 2014). Fatal proportion in red, percentage shows fatality rate.
Adam Britton / CrocBITE

The average size of crocodiles is increasing as the population continues to mature towards full recovery. However, given the very low number of attacks, it’s difficult to assess if this has had any impact on the fatality rate.

Attacks usually happen because people get in the water with crocodiles. Such an obvious cause should be easy to prevent, and indeed this is the case.

Attack risk in Australia is low, largely because of the success of long-running campaigns to warn people of the dangers of swimming in crocodile-populated waters.

What lurks beneath? If you’re in crocodile habitat and you find water, always assume that it harbours a crocodile.
Adam Britton

Those who live locally are generally most keenly aware of the dangers. Sadly, a disproportionate number of attack victims are visitors who aren’t as aware of the risks. The real problem can therefore be interpreted as a failure to communicate risk, and therein lies the solution.

How to not get eaten by a crocodile

Crocodile attacks are traumatic, unfortunate and potentially tragic incidents that generally can be avoided. Australia has an excellent track record in saving people from crocodile attack. Despite having more saltwater crocodiles than any other country, we have low fatality rates because our management and education program is world-class.

Other countries with crocodiles come to Australia for advice on how to manage their crocodile populations and prevent conflict with people.

But there’s still a grey area for many people. How do you know whether it’s safe to swim in northern Australia? What’s the risk of doing so?

We make decisions every day to assess risk, whether we’re driving, walking down the street, swimming in a pool, or taking a boat out on the water. We’ve been trained to minimise the risks we face.

The same is true of going into the bush and facing potential dangers from snakes, mosquitoes or other animals. Sometimes accidents will happen, often because someone decided to push their luck.

Distribution of saltwater crocodiles throughout their range, including northern Australia. Green are viable populations, orange are recently extirpated populations and blue represents their potential for movement within and between countries.
Brandon Sideleau / CrocBITE

But with crocodiles the rules are simple: don’t enter the water in crocodile habitat. In these areas, stay away from the water’s edge, don’t disturb water consistently in the same place, don’t approach or tease crocodiles, camp at least 50 metres from the bank, and don’t go out in small, unstable boats.

Warning signs about crocodiles are there for a reason, to allow you to make an informed decision about your personal safety. Ignore them and you may get away with it, but eventually you will not.

The name ‘saltwater crocodile’ is misleading. They are equally at home in freshwater habitats.
Adam Britton

There’s little doubt that Australia knows how to manage wild crocodile populations. The risk of being attacked by a crocodile here is vanishingly small because crocs and people are managed effectively.

We already have a limited cull of crocodiles; the targeting and removal of specific animals that, through their actions, pose an elevated risk to the public. A wider cull won’t gain anything, at the cost of local livelihoods and our natural resources.

This article was co-authored by Erin Britton, a biologist at Big Gecko Crocodilian Research in Darwin.

The Conversation

Adam Britton, Senior Research Associate, Charles Darwin University

This article was originally published on The Conversation. Read the original article.