Seismic testing critical to Western Australia’s offshore oil, gas and energy industries is dazing, and potentially killing, the state’s valuable western rock lobsters, a new study has found.
- WA scientists have examined the impact of seismic testing on western rock lobsters
- They found a likely 30 per cent initial mortality rate, and modified lobster behaviour
- Consultation is expected to begin next month on WA’s first offshore wind farm zone
The practice is essential to offshore oil and gas exploration and the construction of wind turbines, and involves firing powerful air guns, creating soundwaves that penetrate the ocean floor.
But research by the WA government’s Department of Primary Industries and Regional Development has found lobsters exposed to the testing are significantly impacted.
Offshore crustaceans scientist Simon de Lestang studied the behaviour of lobsters after they were exposed to seismic testing conducted offshore, in shallow water south of Geraldton.
“For the short term, we grabbed each lobster and we put it upside down in a water tank and we timed how long it took the lobster to stand back up again on all of its legs,” Dr de Lestang said.
“We found that any lobsters, out of the group of lobsters that had experienced the airguns from the seismic survey, took significantly longer to stand up again, as if they were a bit concussed, if you will, or dazed.”
‘Concussed and dazed’
The lobsters exposed to the seismic testing were compared to a control group placed in a pot 10 kilometres from where the testing occurred.
Both groups were tagged, and then released into the water after approximately 36 hours.
“A healthy fresh lobster, when you release it, just shoots off under water straight away, straight back to a ledge, whereas most of the seismic lobsters we found more just drifted down again, a little bit concussed and dazed and sort of slowly floated down to the bottom,” he said.
“So there was a real significant difference in their behaviour when we released them again.”
Dr de Lestang then monitored the number of tagged lobsters that could be found in the release area after a month, and over the following two years.
“Initially we saw a significant difference in the recapture rate of the control lobsters which didn’t experience an air gun … essentially we recaptured 30 per cent less of the lobsters, if they had experienced the air guns,” he said.
While he could not be certain the lobsters had died, Dr de Lestang said it was the most likely scenario.
“After one and a half, two months, the recapture rate, if you take into account that initial 30 per cent mortality was actually the same,” he said.
Not just lobster impacted
Dr de Lestang said there was a general willingness from industry to work with fisheries and scientists to minimise the impact on marine life.
But he said more research was needed into the effect of seismic testing.
“Offshore wind farms are becoming more and more a focus of future energy developments and they need to run seismic surveys … where they’re going to put the wind farms to find the appropriate grounds,” he said.
“Oil and gas is worth so much more money that they’re trying to open up new reserves and try and understand sea floor habitats there.
“[If] we develop these new techniques and then we’ve got to work out what impacts they have on the animals and the ecosystem in those areas.”
And Dr de Lestang said is was not just lobsters that were potentially affected.
“It’s the large whales and the dolphins and all the demersal fin fish stocks such as dhufish and snapper as well,” he said.
Danish company Copenhagen Energy has plans to build four offshore windfarms in WA, including what would be one of the world’s largest windfarms off the coast of Binningup.
Consultation for WA’s first offshore wind zone is expected to start next month.
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