2001b. Effect of anthropogenic low-frequency noise on the foraging ecology of Balaenoptera whales. Animal Conservation

• Main Authors: Donald A. Croll, Christopher W. Clark, John Calambokidis, William T. Ellison, Bernie R. Tershy
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Balaenoptera physalus
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.432.6520; http://www.cascadiaresearch.org/reports/Croll-LFA-2001.pdf

The human contribution to ambient noise in the ocean has increased over the past 50 years, and is dominated by low-frequency (LF) sound (frequencies <1000 Hz) from shipping, oil and gas development, defence-related and research activities. Mysticete whales, including six endangered species, may be at risk from this noise pollution because all species produce and probably perceive low-frequency sound. We conducted a manipulative field experiment to test the effects of loud, LF noise on foraging fin blue (B. musculus) and (Balaenoptera physalus) whales off San Nicolas Island, California. Naive observers used a combination of attached tracking devices, ship-based surveys, aerial surveys, photo-identification and passive monitoring of vocal behaviour to examine the behaviour and distribution of whales when a loud LF source (US Navy SURTASS LFA) was and was not transmitting. During transmission, 12–30 % of the estimated received levels of LFA of whales in the study area exceeded 140 dB re 1 µPa. However, whales continued to be seen foraging in the region. Overall, whale encounter rates and diving behaviour appeared to be more strongly linked to changes in prey abundance associated with oceanographic parameters than to LF sound transmissions. In some cases, whale vocal behaviour was significantly different between experimental and non-experimental periods.