[MARMAM] Publications from BRAHSS (Behavioural Response of Humpback whales to Seismic Surveys)
mnoad at uq.edu.au
Mon Feb 29 03:18:51 PST 2016
We would like to draw to the attention of the MARMAM community the recent publication of the following papers:
Dunlop, R. A., Noad, M. J., McCauley, R., Kniest, E., Paton, D., Slade, R. & Cato, D.H. 2016. Response of humpback whales (Megaptera novaeangliae) to ramp-up of a small experimental air gun array. Marine Pollution Bulletin 103(1-2):72-83.
'Ramp-up', or 'soft start', is a mitigation measure used in seismic surveys and involves increasing the radiated sound level over 20-40 min. This study compared the behavioural response in migrating humpback whales to the first stages of ramp-up with the response to a 'constant' source, 'controls' (in which the array was towed but not operated) with groups in the absence of the source vessel used as the 'baseline'. Although the behavioural response, in most groups, resulted in an increase in distance from the source (potential avoidance), there was no evidence that either 'ramp-up' or the constant source at a higher level was superior for triggering whales to move away from the source vessel. 'Control' groups also responded suggesting the presence of the source vessel had some effect. However, the majority of groups appeared to avoid the source vessel at distances greater than the radius of most mitigation zones.
PDF available at http://authors.elsevier.com/a/1SaCw,ashegqZ until 10 April.
Dunlop, R.A., Noad, M.J., McCauley, R.D., Kniest, E., Paton, D. & Cato, D.H. 2015. The behavioural response of humpback whales (Megaptera novaeangliae) to a 20 cubic inch air gun. Aquatic Mammals 41(4):412-433.
Seismic surveys are widely used for exploration for oil and gas deposits below the sea floor. Despite concern they may have an impact on whale behaviour, our knowledge of marine mammal responses is limited. In the first of a series of experiments (the last one involving a full seismic array), this study tested the response of migrating humpback whale (Megaptera novaeangliae) groups to a 20 cubic inch air gun. Experiments were carried out during the southward migration of humpback whales along the east coast of Australia. Groups of whales were focally followed from land stations and/or small boats with observations before, during, and after exposure to a vessel towing the air gun. The source vessel moved either eastwards across the migratory flow or northwards into the migratory flow. In total, there were 18 control trials (where the source vessel ran the compressor and towed the air gun without it firing; n = 35 groups) and 16 active trials (where the air gun was firing every 11 s; n = 32 whale groups). The air gun source level was 199 dB re 1 μPa2.s (Sound Exposure Level [SEL]) at 1 m, and SELs received by the whales varied from 105 to 156 dB re 1 μPa2.s (modal value 128 dB re μPa2.s) for SELs at least 10 dB above the background noise (measured as dB re 1 μPa). Other baseline groups were focal followed when there was no source vessel in the area (n = 25). Results suggested that humpback whale groups responded by decreasing both dive time and speed of southwards movement though the response magnitude was not found to be related to the proximity of the source vessel, the received level of the air gun, the tow path direction, or the exposure time within the during phase. There was no evidence of orientation of the groups towards, or away from, the source vessel in the during phase. Interestingly, this behavioural response was found in the control trials as well as the active trials suggesting a response to the source vessel.
PDF available through Aquatic Mammals or by contacting the authors.
These are the first two major papers of the BRAHSS project, looking at behavioural effects of seismic air guns on migrating humpback whales. This has been a very large study, initiated in 2010. BRAHSS is being funded by the Joint Industry Programme on E&P Sound and Marine Life (JIP) and the US Bureau of Ocean Energy Management (BOEM). The JIP partner companies include BG group, BHP Billiton, Chevron, ConocoPhillips, Eni, ExxonMobil, IAGC, Santos, Statoil and Woodside with some additional funding from Origin Energy, Beach Energy and AWE, coordinated by the International Association of Oil and Gas Producers.
Rebecca Dunlop r.dunlop at uq.edu.au<mailto:r.dunlop at uq.edu.au>
Mike Noad mnoad at uq.edu.au<mailto:mnoad at uq.edu.au>
Doug Cato doug.cato at sydney.edu.au<mailto:doug.cato at sydney.edu.au>
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