Environmentalists say whales are going deaf from seismic surveys for offshore oil and gas. The reality is more complicated.
On a remote beach in Western Australia, a marine scientist picks up a small satellite tracker. The tadpole-shaped device has just washed ashore after months at sea.
Contained within is data showing the movements of a pygmy blue whale as it foraged and migrated along the West Australian coastline.
It is essential information for scientists studying the endangered marine mammal, which was nearly driven to extinction by whaling in the 1800s and early 1900s.
The Australian Institute of Marine Science study will also prove valuable for oil and gas companies such as Woodside, which has funded the research and has the go ahead to conduct seismic surveying 375km off WA's Pilbara coast. The research informs their environmental impact plan.
Woodside's bid to survey for its Scarborough project – the largest Australian oil and gas project in a decade – was halted in September by the Federal Court. The court found the offshore oil and gas regulator NOPSEMA did not have the legal authority to approve an earlier environmental plan, because it had acknowledged Woodside did not properly consult traditional owners.
After resubmitting an environmental plan, Woodside's survey was greenlit by NOPSEMA in early December. The survey began the next day.
Traditional owner and Mardudhunera woman Raelene Cooper said Woodside had only consulted her once since the Federal Court ruling, describing the company's approach as "disrespectful" and "arrogant". Cooper told the ABC she was "heartbroken, devastated and furious" at the fresh approval.
Protesters have this year campaigned outside Woodside's Perth headquarters, with Greenpeace activists holding placards that read "a deaf whale is a dead whale".
Environmentalists argue the sound of seismic surveying is comparable in loudness to an atomic bomb and can cause whales such as the pygmy blue to go deaf, leaving them unable to use sonar to find food.
They call the practice "seismic blasting", which Curtin University marine science professor Robert McCauley says exaggerates what is actually happening in the water and the effect on sea creatures.
McCauley has been involved with research that has been funded by government and fossil fuel companies, including Woodside.
He has studied underwater sound for more than 30 years, revealing impacts of seismic testing that have informed and at times hindered resources companies.
"It would be easier for them if I wasn't around and didn't bring up inconvenient things," he says.
So is a deaf whale truly a dead whale?
"You can't cut a whale up and see if its hearing has been damaged and you can't do hearing tests on whales," says McCauley.
"But generally speaking, we don't believe that whales get deaf from seismic surveys.
"They'd have to be really close to the seismic arrays – probably within a kilometre."
McCauley says that simply doesn't tend to happen.
When faced with seismic vessels in their path, McCauley says that whales have been shown to make a course or speed adjustment to pass a survey comfortably.
"The animal's got possibly a 2,500 to 3,000 kilometre migration ahead of it", he says. "It might deviate five to 20 kilometres to avoid a seismic ship at a comfortable range.
"In the scheme of the migration, it's not a huge imposition. It's still something you don't really want to force pregnant animals to do."
Seismic testing also contributes to an overall noisier ocean, given that sound travels roughly four times faster and many times further in water than it does in air.
A study from 1999 to 2009 in the mid-Atlantic Ocean found that seismic airguns could be heard as far as 4,000km away. It found that airgun noise became the dominant background noise in the ocean and drowned out the calls of fin whales.
But underwater sound is a complex picture and the impact of noise pollution – which is now in the United Nations' sights as a major threat to marine species – is still far from fully understood.
Let's dive in.
What is seismic testing?
Before any drilling can commence, oil and gas companies use seismic surveys to form a picture of what lies beneath the seabed.
The tests use a grid of underwater guns – powered by compressed air – to pulse powerful noise signals through the water.
This is a reconstruction of a seismic airgun array, based on videos and images of the tests.
Loading...The sound that is reflected off the sea floor and the layers below is captured by an array of hydrophones – underwater audio receivers – that extend up to 10km behind a survey ship.
Variations in the sound are used to develop a 3D model of sedimentary rock, water, oil and gas beneath the seabed.
The blasts of sound are fired at two- to 10-second intervals, up to 12 hours at a time, for weeks or months on end.
In Australia, offshore seismic testing has historically concentrated off the western and southern coasts, particularly the hydrocarbon-rich north-west shelf near WA's Pilbara region.
While Woodside's testing is set to happen off the Pilbara coast, several other seismic proposals are currently before the offshore oil and gas regulator NOPSEMA, including a proposal by oil and gas multinationals TGS and SLB to survey 45,000 square kilometres in the Otway Basin north-west of Tasmania — one of the largest surveys ever planned.
Seismic testing produces noise that is especially loud in the lower frequencies that many large baleen whales use to hear and communicate.
Close up, seismic sound reaches up to 250 decibels, which could be many times louder than the loudest sounds made by whales to communicate.
Seismic vessels are required to begin surveys with a soft start and gradual increase of the airguns to warn any nearby whales.
They must also employ observers on board a vessel, who look and listen for whales and other marine fauna. If whales are detected nearby, operations must stop and can only restart when the animals have moved away.
However, Robert McCauley points out that observers are only able to see effectively during the daylight hours of a round-the-clock seismic survey operation. And under good wind conditions they can spot the splash of a surfacing animal fairly easily, but when the wind picks up those sighting cues can become hidden amongst the foam on the sea surface.
The mystery whale
Blue whales are some of the world's most mysterious mammals.
The average person will never see a blue whale in their lifetime, given they disperse widely and far offshore.
Pygmy blue whales are a smaller subspecies but they can still reach up to 24 metres long.
Research scientist Michele Thums tracks the movement of marine megafauna like the pygmy blue whale in her work for the Australian Institute of Marine Science. The work is painstaking and expensive, and Woodside funds some of it.
Thums and her team scan the horizon for surfacing whales, listen for their sounds on underwater microphones, and conduct aerial surveys to locate them. Once within a kilometre, they deploy into a small inflatable boat to attach a barbed GPS tag using an airgun.
At a cost of around $8,000 per tag, they must be certain not to miss a shot.
The challenge is navigating the whales' aversion to boat sounds, making positioning a game of cat-and-mouse.
In any one expedition, Thums says it's only been possible to tag around six to eight animals.
Because a tag's barb affixes only within a whale's outermost skin and blubber layer, it generally won't stay on for very long.
"We can get anything from a few days, up to four months," says Thums. "Our average is about 50 days.
"We really just need to have more data, especially on the southern migration. When you want to understand anything about a species, you need to have a representative sample size. Right now, what we have is probably not representative, but we're getting there."
Despite the incomplete picture, Thums is certain there are seasons of the year when seismic surveyors can avoid directly impacting whales.
The pygmy blue whale is understood to forage south of Australia during summer and migrate north along the WA coast to Indonesia's Banda and Molucca seas for calving season in the winter.
Thums says the whales leave the Perth Canyon feeding area around the end of April, passing through Australia's north-west waters between May and July.
"And then they're on their northward migration up to Indonesia. You might see one up to July, but by August, they're much further north," she says.
Beyond Australia's coastline, pygmy blue whales are known to travel east of Tasmania, south towards the Antarctic Convergence and west to the central Indian Ocean.
While researchers like Robert McCauley say there is little evidence that whales go deaf or die from seismic surveying directly, there may be other subtle effects from the noise.
Australia's conservation plan for the blue whale says that raised noise levels can disrupt a marine mammal's echolocation — the use of sound echoes to navigate and locate objects — and mask their important sound signals, as well as lead to aggression and abandonment of habitat and offspring.
Greenpeace campaigner Richard George says the conservation plan makes clear it isn't known how far a safe distance from seismic testing would be for a whale.
"We know that seismic blasting is one of the loudest sounds in the ocean. We don't know about the impact. For us to then say, 'OK, well, we're going to go ahead and do it anyway' — which is the oil and gas industry's approach — is just way too risky."
In a statement, a Woodside spokesperson said "the likelihood of encountering pygmy blue whales and other cetaceans has been assessed and is expected to be low, even if the timing of the activity overlaps peak periods for northbound and southbound pygmy blue whale migration".
"Scientific studies and modelling were used to inform the impact assessment of the seismic environmental plan, which demonstrate the activities will be performed in a manner that prevents injury to whales, and minimises the potential for biologically significant behavioural disturbance."
How does seismic testing affect other marine life?
Testing the effects of seismic surveying on marine life is expensive, difficult and often provides results that aren't comparable between species.
For instance, results from studies of lobster cannot be applied to understand giant crab.
Marine biologist Ryan Day says the limited species studied tend to be invertebrates valued by fisheries, such as lobster and scallops.
"They get the most attention because there's money involved and if they're getting harmed, that's dollars lost. We have no idea about the broader suite of animals out there."
In the rare instance that researchers are able to conduct studies in the wake of an actual seismic survey, they are often hamstrung by the dangers of working around seismic vessels.
"When they pass over your experimental animals, there's a pretty big time window that you just can't get in and get to your animals, so that delays everything," says Day.
When it comes to sound, some marine mammals are less cause for concern than others.
The hearing of most toothed whales – such as dolphins and porpoises – is confined to the higher frequencies. They appear to be unaffected by the sound of seismic surveys and are even known to approach within metres of operating seismic airguns.
Seismic surveying has been a hotbed of concern for the fishing industry for decades.
Scientists have observed damage to hearing organs in pink snapper and stress responses in Atlantic cod, while fishing industry research has found reduced catch rates in the wake of seismic testing.
But in a landmark study in 2021, scientists designed a large-scale experiment alongside an actual seismic survey vessel and were surprised to find that seismic testing did not appear to affect a community of red emperor fish.
In a recent article, McCauley and Day argue that these seeming contradictions are common in their research field and point to the need for further study.
But the marine life most vulnerable to seismic surveying might be the ocean's smallest.
Zooplankton such as krill have been called the "grass of the sea" for their crucial role as the basis of ocean food chains.
The first study to examine zooplankton exposed to seismic testing caused alarm in 2017, when a startling depletion in surviving plankton was observed.
While Ryan Day says that plankton reproduce quickly and are soon replenished within faster-moving tropical currents, they've attracted calls for further study given their outsized role as food for animals ranging from small fish to the pygmy blue whale itself.
A safer alternative
One solution to the problem of seismic airguns might come from the same man who invented them.
Inventor Steve Chelminski began his career in the 1950s when seismic surveys were being carried out using dynamite as the sound source. Dynamite was dangerous, expensive and produced less accurate data.
Chelminski invented the seismic airgun, which would replace the use of dynamite and become the industry standard for seismic testing today.
But he wouldn't stop there. Now 91 years old, the lifetime Greenpeace member is concerned with the airgun's environmental impact and has set about inventing an alternative.
Chelminski points out that less than a tenth of the energy from an airgun translates into usable seismic data — the rest is wasted.
Several years ago he began testing a new device, which he calls the Tuned Pulse Source.
Resembling a significantly larger airgun, the Tuned Pulse Source produces a lower frequency sound, reducing the emission of frequencies believed to cause trouble for marine life. If the airgun were a trumpet, the Tuned Pulse Source would be a tuba.
Chelminski believes the Tuned Pulse Source's chances of dialling down the ocean noise is down to industry alone.
"Airguns are highly entrenched in industry, and they produce good records for most purposes. New products just have to find their own way."
Woodside said in a statement that the industry is investigating alternative technologies, including one known as a marine vibroseis, but that no such technologies are "currently commercially available".
For environmentalists, the fight against seismic testing is connected to their opposition to the fossil fuel industry.
Woodside's Burrup Hub project is estimated to emit the equivalent of 24 coal-fired power stations operating for 50 years.
But the debate over seismic testing may not simmer down throughout a global transition to renewable energy.
Seismic surveys will be needed to find solid footing for more than 50 offshore wind farms proposed for construction along Australia's coastline in the coming decades, though they will use fewer and smaller airguns over lesser distance.
Robert McCauley cautions that misinformation has already begun to circulate about these smaller surveys before they have gotten underway.
"All those wind farm surveys will get a bad rap before anyone's realised they're nowhere near as big and expansive as the offshore petroleum ones."
Credits:
- Reporting, design and 3D modelling: Jack Fisher
- Editor: Clare Blumer
Notes about data used in this story:
For simplicity, only a single source array is shown behind the survey ship; in reality, there may be two or commonly, three arrays towed 100m apart and operated consecutively.
Historical seismic survey concentration is sourced from Geoscience Australia's National Offshore Petroleum Information Management System (NOPIMS).
Pygmy blue whale distribution is sourced from the Department of Climate Change, Energy, the Environment and Water.