US 'plans stealth shark spies'

Sharks with implants are planned to be released off Florida

Pentagon scientists are planning to turn sharks into "stealth spies" capable of tracking vessels undetected, a British magazine has reported.

They want to remotely control the sharks by implanting electrodes in their brains, The New Scientist says.

It says the aim is "to exploit sharks' natural ability to glide through the water, sense delicate electrical gradients and follow chemical trails".

The unusual project was unveiled last week in Hawaii, it says.

'Steering' sharks

The research is being funded by the Pentagon's Defence Advanced Research Projects Agency (DARPA), according to the magazine.

Remote-controlled sharks do have advantages that robotic underwater surveillance vehicles just cannot match: they are silent, and they power themselves The New Scientist

It aims to build on latest developments in brain implant technology which has already seen scientists controlling the movements of fish, rats and monkeys.

"Neural implants consists of a series of electrodes that are embedded into the animal's brain, which can then be used to stimulate various functional areas," the magazine says.

It says such devices are already being used by scientists at Boston University to "steer" a spiny dogfish in a fish tank.

The next step for the Pentagon scientists will be the release of blue sharks with similar devices into the ocean off the coast of Florida.

As radio signals will not penetrate the sea, communications with the animals will be made by sonar.

The US navy has acoustic signalling towers capable of sending sonar signals to a shark up to 300km (187 miles) away, the magazine says.

It says the scientists will be particularly interested in the animals' health during the tests.

"As wild predators, it is very easy to exhaust them, and this will place strict limits on how long the researchers can control their movements in any one session without harming them.

"Despite this limitation, though, remote-controlled sharks do have advantages that robotic underwater surveillance vehicles just cannot match: they are silent, and they power themselves," the magazine says.

The project was discussed at the 2006 Ocean Sciences Meeting of the American Geophysical Union in Honolulu, Hawaii.