Loaded for Bear — the scientific jury remains out on the effects of seismic surveys

20 May 2024

Amid the very public opposition to and debates around seismic surveys off South Africa’s coast, a key point has often been lost: the scientific jury remains out on the effects of seismic surveys. That point alone should provide opponents with the ammunition required to halt the practice and for the oil industry to proceed with caution.

The issue of offshore seismic surveys for oil and gas is back on the public radar in South Africa.

There were countrywide protests on Friday in support of Wild Coast communities who challenged a bid by oil giant Shell and others to overturn an interdict on seismic surveys in the area.

There is a lot at stake here and the latest act in this unfolding saga is taking place as Shell prepares to divest from its downstream operations – meaning its fleet of petrol stations – in South Africa, while remaining committed to exploration and production activities.

One thing that seems to have been lost in the fog of emotion that has shrouded the issue is the science.

Two-and-half years ago I reported on this issue and noted at the time that – at least according to the peer-reviewed, academic literature I had trawled – the scientific jury on seismic testing remained out.

In short, much of the alarmism in the local press about whales fleeing and dolphins dying and that sort of thing was simply not based on science. But there are legitimate conservation concerns including pointedly the need for more research.

With the matter back on the boil, I did a quick and admittedly unscientific survey of some of the scientific literature on seismic surveys since I wrote about the subject in January 2022.

One, published in September 2023 in the journal Frontiers in Marine Science, offered a systematic review of the scientific literature on the subject.

The authors, from Italy’s National Institute of Oceanography and Applied Geophysics (OGS), winnowed the studies down through a “quality assessment process” to 31 published since 2001.

What they found was some gaping holes in the overall mesh of such studies.

Science has hardly begun to unravel the impact of such surveys on ‘delicate ecosystems’.

“Although several taxa are investigated, most studies focused on effects on marine mammals. There is a lack of research on diverse animal taxa, and no research papers compare the effects on different taxa along the food chain,” the article says.

“Behavioural and physiological effects are the most found by authors in the field. However, observed behavioural changes cannot always be uniquely attributed to the exposure to seismic surveys, as many authors report the influence of other variables (e.g., environmental conditions) during the observations.”

In other words, a lot more research needs to be done to conclusively state if seismic surveys are really bad, moderately bad or have little or no impact on marine wildlife.

Take, for example, this 2017 study cited by the authors concerning African penguins:

“2D surveys were made with four arrays with a total volume of 4,230 in. No information is available on sound levels. During the surveys, penguins showed a marked avoidance of foraging areas and a preference for foraging areas farther away from the vessel,” were among the observations made by the scientists who conducted the study.

So, seismic surveys affect the eating habits of penguins!

Actually, that’s not quite the case.

“Foraging behaviour reverted to normal after the end of the survey. However, a group of penguins stationed in St Croix Island preferred foraging areas closer to the seismic survey vessel’s location in 2013. By contrast, Bird Island penguins consistently travelled away from their colonies, regardless of seismic activities. The authors stated it was not possible to distinguish if penguins’ avoidance reaction was due to a potential change in prey distribution or by a disturbance caused by noise.”

Bottom line: hard to say, more study needed.

This is a common theme throughout the scientific literature analysed by the OGS researchers. One found that sperm whales were not affected by seismic surveys, with: “Uninterrupted foraging dives... observed throughout the exposure.”

One study on harbour porpoises did not find a “correlation between prolonged (seismic) surveys and animal displacement”. Another on New Zealand fur seals was inconclusive, as was one study on the impact of seismic surveys on Canadian snow crabs.

One study found that narwhals changed their horizontal swimming direction to avoid airgun pulses, while another found that sperm whales brushed them off.

Rather more conclusively – and worryingly – a 2015 study cited by the authors found that “after air gun exposure there was a statistically signiﬁcant lower zooplankton abundance” in the area being surveyed.

Any claims by the industry that seismic surveys cause no or minimal damage need to be taken with the same grain of salt as those who claim there will be an apocalypse in the abyss.

Now, that’s bad as zooplankton occupy a key position near the bottom of the marine food chain.

But ultimately, a lot more work needs to be done on this front.

“Research on the effects of marine seismic surveys on marine fauna suffers from a lack of common metrics and standardisation of measurements. Further studies are needed to explore and assess disturbance generated by sources used for seismic surveys, speciﬁcally those planned for academic research, through ﬁeld observations that include long-term consequences, ecosystem-level implications, and indirect effects over diverse animal classes,” the OGS researchers concluded.

That pretty much sums up the state of scientific play on seismic surveys and their impact on marine fauna, though you would not know that when you hear or read some of the claims made by campaigners against such activities off the Wild Coast and elsewhere.

“Shell’s actions will jeopardise the delicate ecosystems upon which these communities depend and undermine their fundamental rights to a clean and healthy environment,” The Cry of the Xcluded and the Botshabelo Unemployed Movement said in a joint statement last week.

Actually, science has hardly begun to unravel the impact of such surveys on “delicate ecosystems”.

But that alone calls for caution. If we really don’t know the full extent of the damage that may or may not be wrought by seismic surveys, oil and gas companies should not be allowed to go full throttle with such activities along South Africa’s coastlines.

Any claims by the industry that seismic surveys cause no or minimal damage need to be taken with the same grain of salt as those who claim there will be an apocalypse in the abyss.

It’s also the case that affected communities have not been properly consulted and that the future of oil and gas is dimming as the green energy transition to address anthropogenic climate change gathers pace.

There are no doubt some ANC cadres who want a vibrant oil and gas sector in South Africa for extractive, rent-seeking reasons – look at how the comrades in Angola and Nigeria have enriched themselves!

But the future of oil and gas is murky, not least because of the scientific consensus on the links between fossil fuel use and climate change. The science on seismic surveys is nowhere close to that kind of consensus – and that is a warning sign to proceed with extreme caution. DM

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