Oceans of noise - Whale and Dolphin Conservation Society

ange. Therefore prey must be closer to the whale for it to be detected. Bain (2002) calculated thata reduction in prey of 80% or more was possible off San Juan Islands.Williams et al. (2002) viewed boat traffic as one factor that can influence the ‘cost of living’ forwhales. Low levels of disturbance may not be problematic in a thriving population, but whencoupled with reduced prey availability and increased contaminant load, short term behaviouralresponses should not be dismissed lightly. Simmonds and Dolman (2000) list the physical,behavioural and perceptual impacts that may be associated with acoustic pollution (see table5.2.1) and continuous noise pollution can lead to permanent avoidance of critical habitat (Erbe,2000).Another ‘special case’ is the use of acoustic devices attached to fishing gear and pens to try tokeep marine mammals away. Death, habituation, displacement and attraction have all beenpostulated as negative consequences of their use (for example, Kemper and Gibbs 1997, Stone etal. 2000, Kastelein et al. 2000, Morton pers. comm.). Again, more research is needed,environmental assessments should be made before such devices are deployed and, preferably,answers should be found that do not depend on the introduction of loud noise.2. Restrictions: Areas that are known to be important biologically might be expected to benefitfrom geographical and/or seasonal restrictions. The Sable Island Gully in Canadian waters andthe Marine Mammal Protection Zone in the Great Australian Bight are examples of areas offeringcetacean’s geographical protection from oil and gas exploration and seasonal protection fromfishing activities.3. Routing and positioning: This involves management of a vessel’s movements or otheractivities around an area where there is a high risk of impacting cetaceans, particularly wherebiologically important areas have been identified. Sufficient information on cetacean movementsis required for such measures to be effective.Similarly, aerial movements may be restricted due to the presence of cetaceans. For example,Australian National Guidelines for Cetacean Observation (ANZECC 2000) state that aircraftshould not operate lower than 1000 ft within a 300 m radius of a cetacean, or approach a cetaceanhead on.4. Operational measures: the success of different methodologies varies for different goals. Partof the methodology for mitigation is usually to observe the reactions of as many individuals aspossible.Indeed, emphasis should be placed on obtaining identification of:(1) As many individuals and sections of the population (mother-calf pairs, maturemale groups, etc.) as possible(2) Pre-exposure behaviours, especially under many different conditions (preyavailability, activities animals are engaged in, time of year, etc.).(3) Changes in behaviours(4) Examination and analysis of such changes; and(5) Redefining mitigation methods and guiding legislation74