Cetaceans face an increasing array of threats from man's continued plunder of the oceans
Cetaceans under siege as man-made perils blight the oceans
29th December, 2011
Whales, dolphins and porpoises have no respite from oil and chemicals, fishing nets, shipping, noise pollution and a host of other dangers brought about by man's unrelenting destruction of the oceans, says Anthony Wall
Noise. A curse – the curse, some would say- of modern life. Noise, day and night. In cities, where more than half of us now live, decibel levels are soaring. Intrusive noise robs us of vital sleep and, say researchers, contributes to all manner of ailments and afflictions. The World Health Organisation pinpoints: stress, insomnia, tinnitus and hearing loss, high blood pressure, aggression, inability to concentrate, tendency to heart attacks.
It has even been suggested that our unquiet lifestyle is driving us mad. Human beings are just not equipped, physically or psychologically, to cope with this rising racket.
It’s self-inflicted torture. But what of the other creatures who share our planet and whose habitat we habitually invade and despoil? They too can be driven to distraction by the pervasive man-made din.
Nowhere is this truer than in the seas around us. Once, the loudest sound to permeate these waters was the lowing of the mighty blue whale. But today… Drilling, blasting and seismic surveys for offshore oil and gas; powerful sonic booms from Naval vessels; the constant thrum of maritime traffic. All these bring distress, sometimes death, to whales (and their dolphin and porpoise brethren). With super-sensitive hearing, 20 times keener than man’s, they are trapped in a newly hostile environment. Traversing the dark deep, whales must rely not on sight but on sound.
Marine biologist Chris Clarke explains: ‘Whales use a variety of sound signals to navigate, communicate, find food and mates. They’re long-lived mammals. The bowhead, for example, can reach an age of 200. So, during its lifetime, a whale will have gone from a natural realm of relative quiet to one in which it may be deafened and forced to shout.’
And mechanical noise pollution doubles every decade. The source of this acoustic bombardment is both military and civilian.
A prowling frigate sends out high-intensity sonar pulses as it hunts for enemy submarines. Elsewhere, oil prospectors are probing the seabed with thunderous giant airguns. Whales flinch and flee.
Nor does the torment end there. Cargo and passenger ships –passing in an ever-lengthening procession- induce further panic. Their propellers resonate on the same frequency as the whales’ echolocation system.
‘It must be like living next to a jam-packed motorway,’ says Chris Clarke, ‘only worse because your hearing is so acute.’
When whales surface too quickly, startled and disoriented, they are known to suffer ‘the bends’. This agonising, potentially fatal condition results from nitrogen bubbles in the blood. Deep-sea divers dread it. But they, at least, can take remedial measures. Unlike the luckless whales.
From around the globe come harrowing pictures of mass strandings as the great beasts (scores at once and with the occasional pod of dolphins for company) beach themselves in a seeming suicide bid. Deliberate or not, it usually succeeds. Sometimes, if rarely, the high-and-dry casualties have been re-floated on a rising tide. In most cases, though, concerned spectators can do little but watch helplessly – and hope. Now and then, a vet will put a far-gone whale out of its misery.
What lies behind these ‘mysterious’ strandings? Again, man is implicated. The US Navy admits that sonar disturbance has led to whales beaching – in the Bahamas, for example- and takes full responsibility.
Not every stranding can be blamed on human activities. But scientists at Woods Hole Oceanographic Institution, conducting post-mortems, find clear evidence of a link between the two. CT scans often reveal bleeding around the whales’ inner ear as well as serious damage to other organs. No one here doubts the cause: anthropogenic (man-made) noise.
Sea mammal specialist Jill Bell adds: ‘Whales also face a more insidious threat, what I call aural smog, a kind of persistent background hum. Their language – clicks, creaks, groans, whistles, chirrups – is becoming less and less audible.’
(Even the ocean-spanning arias of that legendary singer the humpback no longer carry as far as they did.)
‘I believe the well-being of the entire whale family is at risk,’ she concludes, ‘and maybe its long-term future.’
How can we help these amazing animals, an 80-strong clan, early icons of the environmental movement (though still not safe from barbaric harpoons)? Like us, whales are warm-blooded, air-breathing, feed their young on milk, speak to each other, and are renowned for their play, music and intelligence. Unlike us, they have a wholly beneficial effect on the marine ecosystem.
But people, in growing numbers, care passionately about the whale’s fate. A conservation-conscious public, following the lead of bodies such as the WWF, Greenpeace and Friends of the Earth, continues to tell government and industry: ‘Clean up your act’. A start has been made. Rules (not universally observed) already exist to try to shield whales from human hubbub and disruption. We monitor their migration routes, and –whenever practicable- stay away from breeding and calving grounds. Some shipping lanes have been shifted to avoid areas where whales regularly congregate. Speed limits may be imposed on large vessels in coastal waters. The aim is to lessen the likelihood of colliding with whales.
Alas, ‘ship strikes’ are far from uncommon. In 2010, luxury liner Sapphire Princess ploughed into a humpback while cruising off Alaska. No one on board noticed. Only when Sapphire had to increase power to maintain her rate of knots did the captain become suspicious. He halted the ship – to discover a dead whale lodged in the bulbous bow. The humpback was eventually towed away by a tug. This was the ship’s second strike within a year. After an almost identical collision, Sapphire Princess arrived at Vancouver in Canada bearing a whale corpse before her.
One species is especially accident prone, reports the WWF. Northern right whales seem strangely unaware of the peril posed by, say, a looming tanker, and will not attempt to move aside. Fatalities are thus inevitable. Indeed, ship strikes may account for up to 90 per cent of ‘non-natural’ deaths among these sitting targets.
Cetaceans (whales, dolphins, porpoises) have no respite from an ongoing siege. They’re choked and poisoned by circulating oil and chemicals, drowned in entangling nets, while mothers and calves are abruptly parted by full-throttle powerboats with slashing propellers… man’s impact is inescapable.
Discarded litter strews, and sinks into, the sea. Unsuspecting whales ingest it. When biologists in Seattle dissected the carcass of a young grey whale, they were astounded at what they saw. Its stomach contained 50 tonnes of debris. Among the items catalogued: dozens of plastic bags, surgical gloves, a golf ball, small towels and a pair of sweatpants.
Marine pollution takes many forms. Of these, polluting noise is a worse and more widespread problem that we recognised. As Woods Hole scientists point out, virtually all ocean ocean-dwelling animals depend to some degree on their hearing. If that is impaired, the consequences could prove dire, perhaps life-threatening – for fish, say, and also for multitudes of hungry people.
But back to the whales. While our population zooms, billion by billion, theirs struggles to recover from the past onslaught of international whaling. Slow-breeding creatures (a cow may give birth to a single calf every two or three years), whales have never found it easy to meet potential partners in the huge expanse of water where they roam. Now, due to encroaching human clamour, the task is doubly difficult.
They’ve been here 50 million years, an eternity compared with that rowdy arch-invader Homo sapiens. After everything we’ve done to them, whales deserve a break. Let’s give them some peace.
The 180-tonne, 100-foot blue whale is the largest creature that ever lived. Starting as a barely visible egg, it increases in weigh 30 billion times during its first two years.
The sperm whale, immortalised in Moby Dick, can dive two miles deep and stay under for as many hours. Its prey includes the fearsome, fast-moving giant squid which still eludes man.
A humpback hurls its 40-tonne body more than 50 feet into the air as courtship display. One of nature’s truly astonishing spectacles – and the most powerful single action any animal performs.
A bowhead has a mouth as wide as a ferry ramp. This whale is also notable for longevity, only recently revealed when spearheads from the 1800s were found embedded in living specimens.
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