Oceans of noise - Whale and Dolphin Conservation Society

Location: Arctic• Vocal behaviour recorded in beluga whales exposed to the noise produced by a large vesseland an icebreaker ship, altered after exposure. The beluga whales remained vocal and emitteda large proportion of falling tonal, chirp trains, “morse” tonal calls and noisy pulsive calls,thought to be alarm calls.• These alarm calls were produced when the vessels were at a distance of 85km.• Avoidance behaviour began to be observed when vessels were 45-60km away. Received,broad-band (20Hz – 1kHz) noise levels from the shipping at this distance were 94-105 dB re1µPa.• Group integrity and surfacing/diving behaviour also changed.• The beluga whales travelled up to 80km away from the vessel’s course and remaineddisplaced for 1-2 days.Ref: Findley et al. 1990.Location: St. Lawrence Estuary, Canada• Beluga whales changed direction to avoid shipping traffic and increased swimming speed.• Reactions were stronger when the shipping traffic made sudden changes in speed or direction.Ref: Edds and MacFarlane 1987.Location:Bristol Bay, Alaska• Beluga whales stopped feeding and swam down river in response to motorboats, even whenlevels of received noise were low.• The beluga whales showed stronger reactions to vessels with outboard motors than othervessels.• The beluga whales exhibited reactions despite received sound levels being so low theresearchers considered that they would be barely perceptible to the beluga whales.Ref: Stewart et al. 1982, 1983.Location: MacKenzie Estuary, Canada,• Beluga whales avoided tug boats and oil auxiliary vessels even though they were further than2km away.• The beluga group split up and remained separate for several hoursRef: Fraker 1977a,b; 1978.Location: Bristol Bay, Alaska141