Noise pollution could affect marine life feeding habits

Noise pollution caused by military sonars could be harmful to sea mammals such as blue whales and beaked whales, according to new research. Previous research has linked military use of mid-frequency sonar to deaths and strandings of beaked whales in many locations throughout the world. The new research was performed to see whether the use of this sonar caused harm to the animals that resulted in these instances.

Researchers from the Cascadia Research Collective based in Washington attached sound-recording and tracking tags to two beaked whales and 17 blue whales in an attempt to measure the level to which they were subjected to noise pollution in the form of sonar. The researchers used underwater speakers to play simulated sonar in order to measure the responses of each of the animals.

Although the research itself does not explain previous strandings and deaths amongst the whale population, it does suggest that military use of sonar can be damaging to whales and possibly other marine life.

According to the data collected from the research, sonar can cause problems with whales feeding efficiently by disrupting their ability to forage. Whales, especially larger breeds like the blue whale, require a large amount of food every day due to the massive amounts of energy they expend. Any disruption to their feeding ability and patterns, including noise pollution from sonar, can lead to health problems for the animals.

Researchers found that when the blue whales heard the simulated sonar they stopped foraging. It was recorded that one whale ceased foraging for food for 62 minutes, representing a loss of around one tonne of krill from the animal's daily diet.

Doctor Jeremy Goldbogen, leader of the study, said: "Our results provide the first experimental demonstration that individual baleen whales, specifically blue whales, respond to simulated mid frequency sonar. Management decisions regarding baleen whales and military sonar should consider the likely contexts of exposure and the foraging ecology of animals in predicting responses and planning operations in order to minimise adverse effects."