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.

The uranium mine in the heart of Kakadu needs a better clean up plan


Rebecca Lawrence, Macquarie University

Can a uranium mine be rehabilitated to the environmental standards of a national park and World Heritage site?

That’s the challenge faced by the controversial Ranger uranium mine inside Kakadu National Park.

But our new research report found the document guiding its rehabilitation is deficient, and urgent changes are needed for the heavily impacted mine site to be cleaned up well.

Kakadu has been a national park since the 1970s, but the Ranger mine, while surrounded by Kakadu, has never formally been part of the park. This classification is in the interests of resource extraction, and has failed to recognise or protect the area’s cultural and environmental values.

Kakadu National Park encompasses a precious natural heritage. It protects valuable ecosystems of outstanding value, diversity and beauty, and contains the world’s richest breeding grounds for migratory tropical water birds.




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Recent diggings and studies have documented at least 65,000 years of continuous human habitation at a site on the land of the Mirarr people – this is currently the oldest occupation site in Australia.

How was the mine developed?

The boundaries of Kakadu National Park were conveniently drawn around the Ranger mine site through a series of political and administrative negotiations following the Fox Inquiry, which gave a cautious green light for the Ranger operation.

Likewise, Ranger was excluded from the requirements of the Aboriginal Land Rights Act that would have otherwise given the Mirarr people the right to say no to the mine.

Now, as the mining stops and the repair begins, mining companies and government regulators are being tested on their environmental commitment, and capacity to make meaningful change.




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But rehabilitating what is essentially a toxic waste dump is no easy task.

And the inadequacy of the Energy Resources of Australia’s Mine Closure Plan – the key document guiding the rehabilitation – shows they are failing this test so far.

Problems with the Mine Closure Plan

Our new research report – jointly conducted by Sydney Environment Institute and the Australian Conservation Foundation – examines the Mine Closure Plan and finds it is seriously wanting in key areas.

These include significant data deficiencies regarding management of mine tailings (mine residue), land stability, and modelling of toxic contaminants likely to flow off site into Kakadu National Park.

The Mine Closure Plan is almost completely silent on crucial governance questions, such as the Ranger mine’s opaque regulatory processes and rehabilitation, and current and future financing – especially in relation to future site monitoring and mitigation works.




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After the price collapse following the Fukushima nuclear crisis, times in the uranium trade have been tough. Coupled with a mandated end to commercial operations by early 2021, Rio Tinto has accepted the era of mining has now been replaced by the need for rehabilitation.

But the challenge for Energy Resources of Australia and Rio Tinto, who own and operate the mine, is not simply to scrape rocks into holes and plant trees. It is to ensure radioactive and contaminated mine tailings are:

physically isolated from the environment for at least 10,000 years [and that] any contaminants arising from the tailings will not result in any detrimental environmental impacts for at least 10,000 years.

These are time-scales of epic proportions, yet the Mine Closure Plan says little to assure the public this can be achieved.

In fact, Energy Resources of Australia concedes it won’t actually be possible to monitor and measure this over the next 10,000 years, so a model will be required instead. But this model has not been publicly released.

Kakadu is home to more than 280 different types of birds, such as the white bellied sea eagle.
Shutterstock

Rehabilitation success is determined by the mining company

And this speaks to a broader problem with the whole process: the success of the rehabilitation will be judged by criteria created by the mining company.

It is naive to assume a mining company is best placed to propose their own rehabilitation criteria, given their corporate imperative to reduce rehabilitation costs and future liabilities.

And the stakes here are very high. The rehabilitation of Ranger will be a closely-watched and long-judged test of the credibility, competence and commitment of the regulators and the mining companies.




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The Supervising Scientist Branch – a federal agency charged with tracking and advising, but not regulating, the Ranger operation – also made an assessment that should be ringing alarm bells:

[The company’s current plan] does not yet provide sufficient evidence to demonstrate that the current plan for rehabilitation of the Ranger mine site will achieve the required ERs [Environmental Requirements].

The Supervising Scientist Branch’s disturbing initial analysis is a red flag demanding an effective response.

The Conversation reached out to Energy Resources of Australia for a response to this story. A spokesperson told The Conversation the company is committed to the “full rehabilitation” of the Ranger Project Area:

Energy Resources of Australia (ERA) has committed to update the Closure Plan and submit for approval on an annual basis. Updates to the Closure Plan will be made publicly available.

As noted by ERA at the time of release of the Ranger Mine Closure Plan, there are some aspects of closure planning that will be further developed and refined as a result of ongoing studies and consultation. These will be reflected in future updates to the Closure Plan.

ERA is committed to rehabilitate the Ranger Project Area in accordance with the Environmental Requirements as set out in relevant regulations. The final close out of rehabilitation can only occur when the Commonwealth Minister, on advice of the Supervising Scientist and Traditional Owner representatives, is satisfied that the Environmental Requirements have been met.

Australia has a long history of substandard mine closure and rehabilitation in both the uranium and wider mining sector.

There is a real need to see a better approach at Ranger, and the first step in that journey is by increasing the scrutiny, accountability and transparency surrounding this essential clean up work.


This article was updated at 12.25pm, May 7, to include a response from Energy Resources of Australia.The Conversation

Rebecca Lawrence, Affiliate, Sydney Environment Institute; Honorary Associate, Macquarie University, Macquarie University

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

Australia: Climate Change a Major Threat to Kakadu National Park


If climate change continues and reaches the levels predicted there will ba a major impact on coastal areas of Australia. This will therefore mean major problems for Australia’s Kakadu National Park.

For more visit:
http://www.theaustralian.com.au/news/nation/kakadu-treasures-at-mercy-of-climate-change-floods/story-e6frg6nf-1226068252620