Greenpeace and the Greens have welcomed the apparent decision by marine geophysics company PGS to suspend seismic blasting in Great Australian Bight, west of Kangaroo Island.
But they warn the only way to ensure the long term health of the region is for every drilling licence in the Bight to be cancelled.
Greenpeace Australia Pacific senior campaigner Nathaniel Pelle said PGS told an Adelaide newspaperthat it had no plans to conduct seismic testing in the Bight this year as "the companies funding the acquisition have deferred until next year".
PGS was granted the approval in January despite warnings that the tests would put the region's endangered blue and southern right whales at risk and threaten commercial fisheries.
Fellow Norwegian company Equinor meanwhile is proceeding with plans to drill its Stromlo-1 test well about 500km west of Kangaroo Island and is currently going through the approval process.
The PGS news come on the 10th anniversary of the Montara oil well disaster that spilled 23 million litres of oil into the Timor Sea, impacting on more than 90,000 square kilometres of ocean.
"On this day ten years ago, Australia suffered one of the worst oil spills in the nation's history," Mr Pelle said.
"It's fitting that today PGS has announced that it will suspend plans to harm the unique marine life of the Bight by conducting intrusive and potentially fatal seismic blasting."
"Sadly, the reprieve is only temporary. The whales, fishing ports and tourist towns of the Bight will never be fully safe as long as Equinor pursues its reckless plans."
Greenpeace says the news was also welcomed by the Australian Southern Bluefin Tuna Industry Association, which saw Equinor's plans to drill as a direct threat to the healthy oceans that sustain the fishing industry and its thousands of workers.
South Australia's lobster industry was also likely to celebrate the suspension of seismic blasting after a recent study found that seismic activity can impair rock lobsters' ability to evade predators. it says.
The study, conducted by the Research by the Institute for Marine and Antarctic Studies in Hobart and Curtin University in Western Australia, found that seismic blasting damaged lobsters' statocysts, which impacted their ability to right themselves after being flipped over.
Seismic surveys typically involve ships towing an air gun that fires a pulse of sound every 8-12 seconds. Noise from a single seismic airgun survey can blanket an area of over 300,000 km2, raising background noise levels 100-fold (20 dB), continuously for weeks or months.
"The blasts of seismic cannons can be as loud as the epicentre of a grenade and are fired every ten seconds, twenty-four hours a day, for weeks on end," Mr Pelle said.
"While the decision to suspend seismic blasting will be most celebrated in South Australia, it's a win for communities and marine life across the entire southern coast of Australia.
"Equinor's own modelling shows a spill in the Bight could stretch as far as west as Perth, and to the east, far beyond Sydney's iconic Bondi Beach."
"Whether it's the whales that frolic in the Bight's marine parks, the picturesque beaches of southern Australia or the thousands of men and women who work in the fishing and tourism industries, the catastrophic risk of an oil spill means drilling in the Bight will never justify the risk."
Greens Senator Sarah Hanson-Young also welcomed the decision to defer seismic testing in the Great Australian Bight until next year, but says there was still plenty of work to be done.
"The Bight and the industries that rely on it, have been given a reprieve. Now we need permanent protection for the Great Australian Bight," said Senator Hanson-Young, Greens spokesperson for environment and biodiversity.
"Experts warn that there is no safe time to undertake seismic testing. It's a relief to hear the news today that seismic testing will not take place in the Bight this year, however the fight to protect the Bight from Big Oil is still far from over.
"Seismic blasting is the first step to ruining one of the most unique marine environments in the world. Last time seismic testing occurred, sperm whales beached themselves at Ardrossan and died.
"We will not be taking the foot off the pedal in light of this announcement today. The South Australian community will continue the fight to protect the Bight from oil and gas drilling, and dangerous seismic blasting."