Groundbreaking system to prevent collisions between whales and sea-craft
from Inventors and Remarkable People (106 articles)
The world’s first whale anti-collision systems (WACS) Photo: Rolex (Copyright)
Image Gallery ( 7 images )Dr Michel André, for one, is convinced the human uproar is killing whales – and now, apparently, people too. “One of the major short-term and worldwide threats for the sea and marine mammals is constituted by the noise produced by artificial sources,” he says.
In the Canary Islands between six and ten whale collisions a year were being reported, mainly by fast ferry services. When a passenger died after a high-speed ferry rammed a basking sperm whale, André, a marine acoustics expert at the University of Catalonia, was asked to investigate. He decided to start by studying the dead whales. The first two he examined showed severe damage to their inner ears. They were, in short, deaf to certain sounds.
“The inner ear lesions we found in sperm whales came from two resident whales which died after collisions. These lesions affected animals of different ages,” he says, indicating the damage is due to an external factor, not to ageing.
The injuries also occurred at a place in the ear’s sensitive structure corresponding in frequency with the sounds emitted by shipping. To test whether the wider whale population was affected, his team ran controlled exposure experiments on 215 sperm whales in the Canaries in which they played sounds in the same low-frequency range as the affected regions of the ears. The whales failed to react.
While it is impossible to be scientifically certain, Michel André felt that the correspondence between the sound frequency emitted by shipping, the area of damage to the whales’ ears, and the lack of response by other whales to sound broadcast at the same frequency built a compelling argument: “It is very likely that these lesions are due to a long-term exposure to low-frequency sources.”
Since that time, evidence has accumulated around the world that whales are being deafened by human activity. Anatomical evidence indicates that high-intensity sounds such as those produced by active naval sonar cause lesions in whales acoustic organs. These may ultimately kill the whales by causing them to strand, collide with vessels or fail to locate their food sources and so starve.
Aiming to overcome the collision problem André and his team have developed the world’s first whale anti-collision systems (WACS). Knowing that active sonar will only further confuse the whales, he and the team have designed a passive system consisting of a chain of ultra-sensitive listening devices that detect whales round-the-clock, and transmit warnings to nearby vessels. The devices detect the sonic clicks emitted by the whales as they seek prey or communicate with one another. For silent whales, they use sound from other ocean sources, such as waves or rain, reflected off the whales themselves.
A remarkable feature of his system is its ability to single out and track an individual whale among all its “family” members in the same area – a breakthrough made with the help of a West African musician. After years of research, André’s discovery that the sequence of acoustic signals transmitted by the sperm whales could be used to identify individual mammals – a process called Rhythmic Identity Measurement (RIME) – was almost by chance. In attempting to unravel the chaotic rhythms of the sperm whale clicks, he was struck by the similarity between his underwater recordings and African tribal music. A Senegalese griot (drummer) confirmed the likeness and – amazingly – was able to pick individual whales from André’s recordings through their distinctive rhythmic structures.
