Eight kilometres off the harbour of Vilanova i la Geltrú, on the Spanish coast near Barcelona, the fishing vessel Moline rolls in the easy Mediterranean swell. Aboard her, scientists are glued to their instruments, waiting for the telltale clicks that will announce that 10 years’ work has finally paid off. Suspended below them in the blue waters is an elaborate branching antenna of stainless steel, three metres tall and surrounded by a flexible ring four metres across. It quests like a giant ear.
For Rolex Laureate Michel André, it is the decisive moment: the initial sea trial of the world’s first passive whale anti-collision system (WACS), designed to address a growing problem in the planet’s crowded oceans: collisions between ships and the huge sea mammals.
Like a latter-day Ahab (the captain in Herman Melville’s classic American novel, Moby Dick), Michel André has pursued the whale with a passion for over a decade: only his dream has been to save, not to slay. Today, as chairman of the European Cetacean Society, he heads an international campaign against the growing human impact on the seas that is, once again, threatening the future of these majestic beasts.
Sink a few metres into the ocean, and light begins to fade. At 40m you enter endless night, where eyes are of little use and hearing is all. Here, noise moves five times faster and much farther than on land. The oceans are the true realm of sound.
Most sea creatures — from whales and dolphins to fish, squid and shrimps — respond to sound, and many produce it. They use it to hunt and to avoid the hunters, to find mates and food, to guide schools of fish, to navigate, to send messages and transmit warnings, to establish territories and warn off competitors, to stun prey and deceive predators, to “illuminate” their surroundings acoustically, to avoid obstacles and sense changes in water and conditions.
They click bones and grind teeth. They use drum-tight bladders and special sonic organs to chirp, grunt, sing and boom. They belch gases and liquids. They vibrate special organs or their entire bodies. Sounds emitted by sea creatures span the range from 0.1 hertz to 300 kilohertz.
Far from the “silent deep”, the oceans are a raucous babel.
Into this age-long tumult, in the blink of an evolutionary eye, has entered a new thunder: the throb of mighty engines and the thrash of propellers as 46,220 huge vessels plough the world’s sea lanes. The hammer of diesels and scream of outboards as four million fishing boats and more than ten million ferries and pleasure craft surge to and from the thump and ping of military and fishing sonar; but also the deafening crash of seismic ships seeking oil and the low frequency growl of scientific experiments to detect global warming. Scientists report that background noise in the ocean has increased 15 decibels in the last half-century. Enough some say, to mask the normal noise of ocean life going about its business.
Michel André, for one, is convinced that the human uproar is killing whales. “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 1992, a passenger died when a high-speed ferry rammed a basking sperm whale in the Canary Islands. André, a marine biologist and biotechnology engineer, was called on to investigate the increasingly common accidents. Growing sea traffic, faster ship speeds and increasing sperm whale numbers offered one explanation, but he felt there was more to it, so he decided to study 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 observed in sperm whales came from two whales that died after collisions. These lesions affected animals of different ages,” he says, indicating the damage is due to an external factor, not to ageing.
These injuries also occurred at the part of the ear’s sensitive structure that “codifies” the frequency emitted by ships. 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 showed no response.
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 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. The European Cetacean Society states that until recently “it has been very difficult to determine whether man-made sounds actually lead to mortality. However, this situation has changed with the linkage of mass mortality of various cetacean species … with the use of active sonar. Anatomical evidence indicates that such high-intensity sounds can cause lesions in acoustic organs, severe enough to be lethal. It is also suspected that the same sources may produce physically induced or behaviourally induced acute lesions, eventually leading the animals to strand and die.”
André believes many collisions result from the whales’ failure to perceive the approach of a vessel in time to evade it. With his team at the Universitat Politècnica de Catalunya he has been working on a system that can provide ships’ captains with a warning that a whale is in their vicinity. Knowing that active sonar would only further confuse the whales, he and the team designed a passive system consisting of a chain of acoustic buoys (or hydrophones) that listen for the presence of whales round-the-clock, and are monitored by the antenna, which then sends their three-dimensional position to nearby shipping. The buoys detect the sonic clicks emitted by the whales as they seek prey or communicate with one another. For silent whales, they will use sound waves from other ocean sources reflected off the whales themselves.
From Idea to Reality
In 2002, his project was honoured with a Rolex Award, which has helped keep the work alive through technical challenges involved in designing an antenna that was sufficiently strong, sensitive yet flexible enough to withstand the force of ocean currents, and coupling it with the necessary communications technology, software and electronics to enable it to report the location of a whale in real time.
At sea aboard the Moline, André’s efforts were rewarded when his underwater antenna detected a series of artificial clicks that imitated the sounds made by sperm whales, and was able to give a position for the source. These enabled his team to test his elaborate antenna in a “real-life” setting, and calibrate the equipment.
“The signal acquisition, the mechanics and the real-time positioning worked fine,” he reports. The next phase is to detect live sperm whales vocalising off the Balearic Islands. The hardest challenge is to detect silent whales by their sound reflections.
The Rolex Laureate is seeking a commercial partner for his project. Its ultimate success and use worldwide, he says, depend on society at large and on politics, and on the response to the plight of sea creatures impacted by noise.
“The more noise we put into the ocean, the more we affect the way sea dwellers communicate and live,” André says. “This means that we are compromising their survival… Due to its low frequency components, a sound source may propagate over thousands of miles. The control of these sources constitutes a scientific challenge and an important responsibility for society and governments.”
Published in 2006