Whales, back from the brink of extinction in the last two decades, seem to be facing another seaborne danger: this time from accidental noise pollution caused by the low humming of ships’ engines and the whirring of propellers.
It has been thought for some time that large baleen whales in particular – the whales that feed on krill, like blue, minke and humpback whales – have a communication system that uses sound at, or similar to, the frequency of that emanating from the engines and propellers of large ships. The number of whales suffering from direct surface collision or entanglement in fishing nets has also been a source of concern, but the amount of statistical evidence of the effects of shipping noise has until recently been absent.
One aspect of whale communication has been revealed by biologists’ research which lends some credulity to the noise pollution idea: this is the finding that large whales like Northern Right Whales and Humpback whales make low pitched sounds that can travel and be heard up to two hundred kilometres away from the whale making the sound. It is not known exactly why whales do this. Speculation has centred on the possibility that whales locate and communicate with potential mates and keep in contact with an extended social group through these sorts of vocalisations.
It is also known that male Humpback whales, in particular, use extensive and varied songs in order to court females. These songs can be heard a very long distance away and no doubt this helps a species in which the individuals are widely spaced out across the vastness of the ocean.
A survey done immediately before and after the 9 / 11 Al Qaeda inspired massacre in New York also points towards the effects of shipping. A whale research group was inadvertently taking samples of whale faeces floating on the surface of the ocean off the North Eastern seaboard of the USA on a regular basis before the attacks on the Twin Towers. By analysing faecal composition, traces of a hormone released by the whales showed the extent of their distress. Just after the attack, all shipping stopped for a short period. The researchers found that the distress signals being given off by whales during this “quiet” period were significantly less than normal, indicating that whales suffered less when the oceans were free of shipping noises. The group could not adequately explain the reduction for any other reason.
More disturbingly, research from whale scientists seems to show that the overall distress levels seem to be slowly rising from whales and this might be associated with the overall increase in the amount of shipping traffic.
The hormones that have been monitored are similar to those in humans that help us to get ready for the “fight or flight” response. This is totally natural, but when the levels of the hormone build up in an animal’s (or a person’s) body it can have detrimental effects on the animal’s health and well being, lowering the ability of the immune system to respond as well as leading to stunted growth and a reduction in reproductive performance.
Whale researchers say that additional sounds in the maritime environment, like sonar devices being let off during oil exploration and torpedo releases during navy exercises, also contribute to levels of extraneous and potentially damaging sound in the depths of the ocean.
Contrary to what people might think, sound travels extraordinarily well through water, being transmitted many times faster than through air.
Whales use sound to communicate with their fellow creatures as well as to navigate and search for food.


















