New research has shown that the noise produced by ships causes chronic levels of stress in whales.
Whales use sound to communicate, locate food and to navigate. Previous studies have shown that the noise produced by human activities can cause whales to change their calling patterns, but these most recent findings are the first that demonstrate that noise pollution actually causes physical harm to whales.
Scientists used specially trained scent-detection dogs to locate and collect the faecal balls of North Atlantic right whales in the Bay of Fundy, Canada. During 2001, noise pollution in the Bay of Fundy fell dramatically, as marine traffic was halted following the September 11th attacks. Faeces gathered during this quieter period showed a significant reduction in the level of stress hormone being produced by the whales.
Harmful levels of stress
Noise levels in our oceans, produced by ship’s propellers, military sonar and underwater explosions, have increased tenfold since the 1960s. The stress that the current noise levels are causing could be detrimental to the health of whales in the long term.
“Instant responses to stress – like running away from a tiger – can be life-saving,” explains Dr Rosalind Rolland, lead author on the study. “But if it becomes chronic, it causes profound depression of the immune system, making them vulnerable to disease, and it depresses reproduction.”
North Atlantic right whales are currently one of the world’s most endangered species of whale, with less than 500 remaining. Dr Roland believes that damage caused by noise pollution could further impede the recovery of this species.
A solvable problem?
While there are currently no international standards on the level of permitted noise pollution in our oceans, Dr Rolland believes the problem is a solvable one. Improving the efficiency of ship engines would not only reduce the level of noise, but also reduce the level of fuel consumption. However, with up to 50,000 large ships travelling our oceans every day, this problem may take some time to rectify.
Read more on the story in The Guardian – Shipping causes ‘chronic stress’ to whales.
Find out more on the BBC news website – Whales ‘stressed by ocean noise’.
Becky Moran, ARKive Species Text Author