Whales choose to ‘live or eat’ amid impact of noise, say Scots scientists
A NEW study looking at the effects of excessive underwater noise on whales, dolphins and porpoises has revealed that they can often face a choice of living over eating when they hear a threat.
Researchers, including scientists from the University of St Andrews, have discovered that manmade underwater noise pollution is picked up by whales in a similar manner to the way they sense natural predators, explaining why some species are particularly sensitive to noise disturbance.
The findings reveal that whale, dolphin and porpoise responses to sounds such as military sonar systems are shaped by how they evolved to respond to natural predators like orcas, and that underwater noise disturbance created by humans is causing them to stop foraging for food and, therefore, become weakened and more vulnerable.
The research team found that Navy sonar caused cessation of foraging in all four species of whale they studied – northern bottlenose, humpback, sperm, and long-finned pilot whales – which all rely on acoustic signals to assess risk from attack as well as to find food themselves.
Underwater noise pollution is picked up by whales in a similar way they sense natural predators, explaining why some species are particularly sensitive to disturbance.
The study states: “Our results with four cetacean species indicate that they use acoustic information to assess predation risk and have evolved mechanisms to reduce predation risk by ceasing foraging.
“Species that more readily gave up foraging in response to predatory sounds of killer whales also decreased foraging more during 1 to 4kHz sonar exposures.
“This advance in our understanding of the drivers of disturbance helps us to predict what species and habitats are likely to be most severely impacted by underwater noise pollution in oceans undergoing increasing anthropogenic activities.”
The study goes on to say that the variability in responsiveness to sonar is expected “as the fitness payoffs of choosing life over dinner depend both on the individual (for example, sex, age and body condition) and environmental context (food availability), as well as predation risk.”