There is currently a great deal of concern about how man made noises such as military sonar, oil and gas exploration activity and commercial shipping may adversely affect marine mammals. Despite this little is known about how anthropogenic noise really does affect marine mammals. The BRAHSS project is a major project over four years aimed at understanding how humpback whales respond to the sounds of seismic surveys, used by industry to find undersea oil and gas deposits, and to provide the information that will allow these surveys to be conducted efficiently with minimal impact on whales. 

Seismic surveying is used by the oil and gas industry to locate oil and gas under the sea floor and in geosciences research of the rock structure under the sea. It involves the generation of high level pulses of sound that penetrate the rock layers below the sea floor to provide information about the underlying rock strata.

BRAHSS is a large, four-year collaborative study investigating the effects of seismic airguns on the behaviour of humpback whales during migration. This full study aims to test how humpback whales respond to seismic airguns on both the East Coast and West Coast of Australia. The project will be one of the largest, most complex and advanced Behavioural Response Studies in cetaceans ever undertaken. 

The broad objectives are:

  • To determine the response of humpback whales to a typical commercial seismic survey in terms of the variables affecting the response, such as the received sound level, relative movements of seismic array and whales and distance between them, behavioural state and social category of the whales, and environmental variables.
  • To determine the response of humpback whales to soft start or ramp-up and its components, to assess the effectiveness of ramp-up as a mitigation measure in seismic surveys and the potential for improving the effectiveness.
  • To relate these responses to the range of normal behaviour and the response of the whales to other stimuli, such as passing ships, using the substantial body of knowledge that exists from previous research for the populations studied. Knowledge of the function of the behaviour, the population dynamics and the biology of the whales will allow us to infer and model effects on life functions.

The project involves leading researchers from several Australian institutions including the Universities of Queensland, Sydney and Newcastle, the Curtin University of Technology, the Australian Antarctic Division and the Defence Science and Technology Organisation.

Funding is being provided by the by the Joint Industry Programme on E&P Sound and Marine Life (JIP) and by the United States Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE). This is part of the JIP broad investigation in to the potential interaction between the sounds that are generated by the offshore industry and the marine environment. The JIP is managed by the International Association of Oil and Gas Producers (OGP). The contributing companies are BG group, BHP Billiton, Chevron, ConocoPhillips, Eni, ExxonMobil, IAGC, Santos, Statoil and Woodside. The International Association of Geophysical Contractors (IAGC) is also a contributor.

The study aims to provide information that will reduce the uncertainty in management and mitigation of potential effects of seismic surveys on whales, allowing surveys to be conducted efficiently with minimal impact on whales. The main objectives are to study the behavioural reactions of humpback whales to seismic air guns to determine if these have longer term biological effects, and also to determine whether ramp-up of air guns at the start of a survey is effective as a mitigation measure. (CEAL project leaders Mike Noad &Rebecca Dunlop)

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