When a confused whale swam up the Thames to its death last year, marine biologists blamed seismic surveying for sending it off course.

Now a listening system that searches for whales and dolphins could help save hundreds of such creatures.

The equipment, developed by scientists at the University of Plymouth, scans for calls and songs to pinpoint their exact location beneath the waves.

Conservationists think that underwater explosions used by the oil industry and geologists to examine the sea bed disorientate nearby marine mammals and cause many beach strandings.

About 800 whales, dolphins and porpoises are stranded on British shores every year - a figure that has doubled in a decade. Over the same period, a big rise has been reported in the amount of underwater noise generated by people.

The new system, which will go on trial on a survey ship this summer, involves picking up the series of high-pitched clicks and whistles from the animals on a network of underwater microphones. The data is used to calculate their positions so that undersea blasts are not set off near them.

“Whales and dolphins vocalise in their everyday lives to communicate, navigate and find food,” said Ross Compton, the research project’s leader. “Until now, there has been no reliable way of using these calls to locate the animals.

“They spend 80 per cent of their time under water, so visual searches are not terribly useful.”

More than 100 seismic surveys are carried out in British waters every year, each involving dozens of daily blasts. The sound waves bounce off undersea rocks and are used to map the ocean floor and search for oil below it.

Seismic surveying in the North Sea is thought to have disorientated a young northern bottle-nosed whale last year, diverting it from its migratory route and sending it on a fatal journey into London.

At close range, loud noises are also thought to damage the hearing of whales and dolphins, making it harder for them to navigate and find food.

Recent research has also suggested that underwater noise from military sonar and seismic surveys may be responsible for mass strandings of marine mammals by producing the equivalent of the “bends” suffered by divers.

It is thought the acoustic pulses frighten the animals into surfacing too quickly, resulting in bubbles in the blood and tissues that produce decompression sickness and leave them disorientated. Under British law, survey ships must have observers on deck to confirm there are no marine mammals in the area before such work begins but, as the animals spend much of their time under water, they can be difficult to spot, particularly in bad weather.

In most areas, whales and dolphins must be more than half a mile from a survey, but in some conservation areas the distance increases to almost three miles. Mr Compton, who is working with the seismic survey company Westland GeoProjects, is using microphones towed behind a ship to pick up calls from the animals to help survey teams locate them.

Mark Simmonds, of the Whale and Dolphin Conservation Society, said: “Noise underwater is something we don’t understand very well. Whales and dolphins use sound for a range of things crucial for survival. By introducing new loud noises into that environment, the effects can range from physical harm to displacing them and interfering with their navigation.”

Rob Williams, of the sea mammal research unit at the University of St Andrews in Fife, studies the effects of human disturbance on whales. He said: “Anything that tells us that there are animals in a given location is very useful.

“My only concern is that silence should not be used to infer the absence of animals. Not all species are vocal and even the vocal species, like killer whales, may be silent for hours on end. These methods may reduce the risk of harm, but will not eliminate it.”

Source: http://www.telegraph.co.uk

Scientists have enlisted some supremely qualified recruits to retrieve important data on one of the most remote and inhospitable places on earth. And all these recruits want is a nice fish dinner.

That’s because they are narwhals, a deep-diving arctic whale famous for the males’ long, spiral tusk.

University of Washington marine biologist Kristin Laidre and colleague Mads Peter Heide-Jorgensen of the Greenland Institute of Natural Resources have equipped three narwhals with sophisticated satellite transmitters to send data on water temperatures in ice-clogged seas between Greenland and Canada.

“In a way, we’ve converted these animals into oceanographers,” Laidre said. “We’re not only learning about their ecology and biology, but we’re collecting data that can be useful for bigger-picture climate change questions.”

The whales are collecting data about Baffin Bay, their winter habitat between northeast Canada and Greenland. Baffin Bay joins with the Arctic Ocean to the north and west and the Atlantic Ocean to the south via Davis Strait.

Laidre said there had been essentially no such data on this region from wintertime, when it is covered in ice and impassable to ships. It is an important link in global ocean circulation and a good place to detect ocean changes in due to climate change.

But the whales thrive in these winter conditions. They dive to depths of 1,800 metres to feed on Greenland halibut, a deep-water flatfish living on bottom of Baffin Bay.

The devices placed on their backs record water temperatures at various depths and track narwhal movements and diving behavior, adding to the understanding of these elusive whales. The devices transmit 400 readings a day.

“If you can attach an instrument to a whale that’s going down to the bottom of Baffin Bay and coming back up again - diving 1,800 meters over and over again - you can collect some fantastic data that only very, very sophisticated oceanographic instruments can collect,” Laidre said.

The US National Oceanic and Atmospheric Administration and Greenland Institute of Natural Resources back the research.

The world narwhal population is close to 100,000, with about 50,000 to 70,000 in the Baffin Bay area, Heide-Jorgensen said. They grow to about 5 metres long, with the tusk adding up to 2.7 metres more. They weigh upward of 1.5 tons, with males bigger than females.

The aim is to equip eight to 10 whales with the devices. Doing so is easier said than done.

The scientists set nets to catch the whales, and monitor the nets 24 hours a day.

When a whale becomes ensnared, the scientists jump into two inflatable boats and rush to the scene, knowing they need to get the whale to the surface so it can breathe. The whales wildly try to escape, but calm down after being placed in a sort of sling between the boats, the scientists said.

The scientists then attach the devices with two plastic pins - painlessly, they say - to a ridge on the animal’s back.

The three whales now sending data were trapped last summer. No whale has been harmed in the process, they said.