Determining the behavioural dose-response relationship of marine mammals to air gun noise and source proximity

• Published in: Journal of Experimental Biology
• Main Authors: Dunlop, Rebecca A., Noad, Michael J., McCauley, Robert D., Scott-Hayward, Lindesay Alexandra Sarah, Kniest, Eric, Slade, Robert, Paton, David, Cato, Douglas H.
• Other Authors: University of St Andrews. Statistics, University of St Andrews. Centre for Research into Ecological & Environmental Modelling
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: Anthropogenic noise; Behavioural response study; Received level; Humpback whale; Seismic air gun; QH301 Biology; NDAS; SDG 14 - Life Below Water; QH301; Humpback Whale
• Online Access: http://hdl.handle.net/10023/15827; https://doi.org/10.1242/jeb.160192

Funding was provided as part of Joint Industry Programme on E&P Sound and Marine Life, managed by the International Association of Oil & Gas Producers (IOGP). The principal contributing companies to the programme are BG group, BHP Billiton, Chevron, ConocoPhillips, Eni, ExxonMobil, IAGC, Santos, Statoil and Woodside. The US Bureau of Ocean Energy Management (BOEM), Origin Energy, Beach Energy and AWE Limited provided support specifically for the BRAHSS study. The effect of various anthropogenic sources of noise (e.g. sonar, seismic surveys) on the behaviour of marine mammals is sometimes quantified as a dosetextendashresponse relationship, where the probability of an animal behaviourally 'responding' (e.g. avoiding the source) increases with 'dose' (or received level of noise). To do this, however, requires a definition of a 'significant' response (avoidance), which can be difficult to quantify. There is also the potential that the animal 'avoids' not only the source of noise but also the vessel operating the source, complicating the relationship. The proximity of the source is an important variable to consider in the response, yet difficult to account for given that received level and proximity are highly correlated. This study used the behavioural response of humpback whales to noise from two different air gun arrays (20 and 140 cubic inch air gun array) to determine whether a dosetextendashresponse relationship existed. To do this, a measure of avoidance of the source was developed, and the magnitude (rather than probability) of this response was tested against dose. The proximity to the source, and the vessel itself, was included within the one-analysis model. Humpback whales were more likely to avoid the air gun arrays (but not the controls) within 3 km of the source at levels over 140 re. 1 μPa2 s-1, meaning that both the proximity and the received level were important factors and the relationship between dose (received level) and response is not a simple one. Publisher PDF Peer reviewed