Oceans of noise - Whale and Dolphin Conservation Society

Location: Mexico• Gray whale vocal behaviour changed when exposed to the sound of an outboard motor andthe sound of a drillship. Call rate increased after exposure to the former and decreased afterexposure to the latter.• No avoidance reaction was evident during the underwater playbacks and some whalesapproached the amplifiers playing sound from outboard motors.• The average received levels of calls (loudness) increased in response to actual boats orplaybacks of boat noise, suggesting that the animals vocalised louder possibly to avoid callsbeing masked by boat noise.Ref: Dalheim 1987.Location: Mexico.• Gray whales abandoned San Diego Bay as the result of exposure to intense shipping activityand dredging.• The gray whales returned only after vessel traffic decreased.Ref: Bryant et al. 1984.Location: Mexico.• Gray whales exhibited short-term escape when approached by boat traffic in breedinglagoons.• Responses were stronger when exposed to fast or erratically moving vessels.Ref: Swartz and Cummings 1978; Swartz and Jones 1978, 1981.Location: Chukotka, Western Russia• Summering gray whales displayed avoidance reactions and moved away if a vessel waswithin 350-550m, but no avoidance reactions occurred in response to distant vessels.Ref: Bogoslovskaya et al. 1981.Location: San Diego, USA.• Gray whales abandoned San Diego Bay as the result of exposure to vessel traffic.• The gray whales returned only after vessel traffic decreased.Ref: Reeves 1977.Location: Mexico156