Acoustic trauma risk low for South Australia’s beach-wrecked dolphins

When record numbers of dead dolphins washed up on South Australian beaches in March and April of 2013 (33 in total as of May 1st), marine biologists and veterinary scientists found themselves busy conducting necropsy after necropsy on all dolphin bodies which were able to be collected. According to the South Australian Environment Department (DEWNR), a combination of Dolphin Morbillavirus (DMV) and systemic fungal infections appear to be the most likely causes of death. Many test results are still anticipated, and one of the additional concerns expressed my members of the community was harm due to acoustic trauma. A recent example of cetaceans harmed by acoustic trauma exists in the results from dolphin necropsies from Peru in 2012.

Offshore Oil & Gas Exploration – Seismic Surveying

The State Government’s Environment Department (DEWNR) suggested to us that the likelihood of acoustic trauma was low, due to the majority of identified beach-wrecked dolphins being Indo-Pacific Bottlenosed Dolphins, an inshore species. This sounds reasonable, when it is considered that offshore oil and gas exploration typically occurs in much deeper water. For example, BP is currently seeking Federal approval to drill four exploration wells in the Great Australian Bight, at ocean depths ranging from 1,000 to 2,500 metres. Public comments in response to this referral are accepted until May 27, 2013. BP’s seismic surveys in preparation for this proposed drilling were conducted in 2011 and 2012. More recently, BP commenced a research program in the Great Australian Bight in collaboration with CSIRO and MISA on April 4th of 2013.

Offshore Oil & Gas Exploration Licenses in SA waters - May 2013

Offshore Oil & Gas Exploration Licenses in SA waters – May 2013

In South Australia, there are currently two major players in the offshore oil and gas game: BP and Bight Petroleum. According to Bight Petroleum’s website, the company does not intend to conduct seismic surveys until March through May of 2014. The specifics of BP’s recent activities in SA are a little harder to track, due in part to the delayed disclosure of seismic survey information by via the State Government’s SARIG website.

South Australia’s Department of Mines and Energy (DMITRE) hosts a public access geoserver known as SARIG but it is yet to publish any offshore seismic survey lines recorded from 2010 to the present. While active license boundaries (shown in the map above) give some indication of areas of current exploration interest, it is our opinion that the current lack of data gives the public the false impression that no seismic surveying works have been conducted off South Australia’s coast this decade. This is not the case, as evidenced by BP’s previous referral to the EPBC Act which indicates that Federal approval was granted for BP to undertake seismic surveys between October 2011 and May 2012. Since all seismic surveys in Commonwealth waters should theoretically be referred for Federal approval, it is likely that BP’s surveys in 2011 and 2012 were the only ones conducted recently. In accordance with their approval, such surveys would have concluded well short of the recent dolphin deaths.

So what can we glean from this information? Well, since there is no overlap between seismic surveying activities in SA waters and the timing of the beach-wrecked dolphins of March and April 2013, the implied risk from seismic surveying to cetaceans in this specific case is reduced considerably. The vast distance between survey activity areas and the locations of beach-wrecked dolphins also makes any direct link between the two events extremely unlikely.

Active Sonar testing and Naval activities

Seismic surveying for oil and gas however, is not the only potential cause of acoustic trauma to whales and dolphins. After discovering this desktop study report from SARDI researching grounds for future naval sonar testing, we asked the Defense, Science and Tehnology Organisation about their plans and activities in 2013. We were pleased to receive the following written response, which should allay some community concerns regarding this activity’s potential for environmental impact… at least for the time being. Naval use of active sonar is known to be a threat to cetaceans, so needless to say, the Department has good reason to tread lightly.

DSTO have not undertaken any active sonar tests in Gulf St Vincent, Spencer’s Gulf, nor anywhere else in South Australian waters in 2013.

The Air Warfare Destroyers, being built in Adelaide, will need a test and evaluation programme to demonstrate the functionality of their sonar systems.  The tests are programmed for 2015. By way of preparation, DSTO conducted a literature review of potential test sites between June 2011 and May 2012. This is the document to which you refer in your letter.

Air Warfare Destroyers will require sonar testing in South Australian waters in 2015

Air Warfare Destroyers will require sonar testing in South Australian waters in 2015

In addition DSTO undertook a series of measurements of oceanographic parameters in a limited area west of Kangaroo Island, involving three deployments of a “Slocum Glider“, and sediment sampling.  The Gliders measured ocean temperature and conductivity, and recorded ambient ocean noise levels between December 2011 and April 2012.  These gliders do not transmit sound into the ocean.

DSTO measured sound propagation characteristics at the Kangaroo Island site in February 2012.  The sound propagation measurements were undertaken in strict compliance with conditions established by the Departmentof Sustainability, Environment, Water, Population and Communities (SEWPaC) and the Australian Defence Organisation (ADO) in order to meet the requirements of the Environment Protection and Biodiversity Conservation Act 1999. The trial was completed without incident.

DSTO Sound Propagation Measurement Site - February 2012

DSTO Sound Propagation Measurement Site – February 2012

It is interesting to note that DSTO has previously referred sonar activities for Federal approval, as seen at this link. The ‘sound propagation measurement’ activity mentioned above (details of which we are yet to obtain) was not referred to the EPBC Act, and therefore occurred without the knowledge of the general public. It appears that no DSTO sonar testing activities have been referred to the Act publicly since 2002. Have such tests occurred in the intervening years? Are such tests no longer disclosed for reasons of national security or should the public have a right to know about the Department’s intentions, associated risks and be provided an opportunity to pass comment before they are authorized and undertaken? We shall anticipate some further answers on these matters in the weeks ahead.

For the time being, as citizen scientists of Cuttlefish Country we have attempted to investigate any possible association between these unlikely sources of potential harm from the as-yet-unconfirmed causes of death of cetaceans in March and April. Meanwhile, the Dolphin Trauma Group team of scientists’ work continues and many lab results are still pending. We thank the DSTO for their professional and detailed response to our inquiry and anticipate a reply from DMITRE regarding the missing seismic lines from BP’s seismic surveys.

During these distressing times, we can only remain vigilant and hope that future industrial and defence users of the marine environment continue to disclose their intentions to the public, and answer community and environmental concerns well ahead of commencing operations.

Reminder: Public comments on BP’s proposal to drill exploration wells in the Great Australian Bight will be accepted until May 27th. All relevant documentation can be found here.


Dan Monceaux is a South Australian documentary filmmaker and the director of Cuttlefish Country.

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