One of the products of two international Fisheries and Oceans Canada-led workshops to develop “a risk-based framework for assessing cumulative impacts of marine development projects” has just been published.

The work has been published in the Canadian Journal of Zoology titled A systematic review on the behavioural responses of wild marine mammals to noise: the disparity between science and policy. The work was led by Dr. Catalina Gomez (DFO) and her co-authors from DFO, George Mason University and SMRU Consulting Canada, with funding from the Strategic Program for Ecosystem-Based Research and Advice (SPERA) at Fisheries and Oceans Canada and NSERC.

behavioural response to noise

Probability density function (via Kernel density estimation) of the behavioural severity (low, moderate, high) of Low Frequency baleen whales and Mid Frequency toothed whales in relation to Received Levels of continuous, Mid-Frequency Active Sonar (MFAS), and seismic/explosion sound sources. The values provided for behavioural score responses and RLSPL are the maximum reported for each study reviewed (RLSPL ranged between 82 to 180). N = number of data cases


The study focused on the recurrent conclusion about the need for considering context of exposure, in addition to received levels, when assessing probability and severity of behavioural responses. In North America, generic (multi-species) noise thresholds continue to be recommended and used to assess impulsive noise impacts on behaviour (e.g., 160 dBrms received level) of all species of marine mammals present.

This systematic analysis emphasized that behavioural responses in cetaceans (measured via a linear severity scale) were best explained by the interaction between sound source (continuous, sonar or seismic/explosion) and functional hearing group (a proxy for hearing capabilities). Importantly, more severe behavioural responses were not consistently associated with higher Received Level, and vice versa (See figure). This indicates that monitoring and regulation of acoustic effects from activities on cetacean behaviour should not exclusively rely upon the current generic (multi-species) Received Level thresholds. The authors recommend, if species-specific dose-response functions are not available, then the behavioural response severity score approach might be replaced with a response/no response dichotomous approach that can represent a measure of impact in terms of habitat loss and degradation.

The paper is available through request:

Gomez, C., Lawson, J., Wright, A.J., Buren, A., Tollit, D., and Lesage, V., (2016) A systematic review on the behavioural responses of wild marine mammals to noise: the disparity between science and policy.  Canadian Journal of Zoology, 0, 0, 10.1139/cjz-2016-0098

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