BRAHSS - Behavioural Response of Australian Humpback whales to Seismic Surveys, is a 6 year collaborative study, investigating the effects of seismic airguns on the behaviour of humpback whales during migration. The study aims to assess how humpback whales respond to seismic airguns during seismic surveys. It is one of the largest and most complex behavioural response studies ever undertaken on cetaceans. BRAHSS is a collaboration between the Universities of Queensland, Sydney, Curtin University and the Defence Science and Technology Organisation, and field work included participants from several other organisations and volunteers.
This project as a whole aims to provide information that will reduce the uncertainty in evaluating impacts of seismic surveys on humpback whales, leading to management and mitigation measures that allow surveys to be conducted efficiently with minimum impact on the whales.
Peregian beach, two hours north of Brisbane, has been a hub of humpback whale research on the east coast of Australia since 2002 when a project known as HARC – the Humpback whale Acoustic Research Collaboration – started there. In many ways BRAHSS has become an extension of HARC, building on the data sets and methodologies developed from 2002-2009 field seasons, but also including significant additional acoustic measurements. BRAHSS is a Behavioural Response Study (BRS) otherwise known as a Controlled Exposure Experiment (CEE), the aim of which is to help us better understand how humpback whales respond to sounds from seismic air guns. To assess behavioural responses accurately we need to know how the whales’ responses might differ from those produced by natural stimuli (e.g. wind generated sea noise, conspecific sounds) or other anthropogenic sounds (e.g. passing ships and recreational vessels), and how social context might affect their responses. Singing whales, particularly their interactions with other non-singing conspecifics, will also be studied as part of BRAHSS. The data collection includes collecting behavioural data on whales as they move through the study area, conducting real-time, simultaneous acoustic and visual tracking of whales, exposure to real seismic air guns, the deployment of DTAGs, and the collection of fluke photographs and skin biopsies. The sound field is measured at many points throughout the study area to provide acoustic characterisation of the site and sound propagation.
Bowhead whales are increasingly coming into contact with human activities in the Arctic, such as the oil and gas industry which directs low-frequency sounds into the environment as part of their seismic (acoustic) surveys to discover hydrocarbon deposits. But, bowhead whales are also low-frequency specialists and are therefore thought to be sensitive to these industrial seismic sounds.