Scientists Track Fish With GPS, RFID

"Scientists in New York State are putting battery-powered implants, hydrophones, GPS and sonic waves to use in the Hudson River, where they are tracking and studying several species of fish. About 45 fish are swimming in Hudson River's salty estuary emitting sonic waves, allowing New York's Department of Environmental Conservation to track them with hydrophones and GPS. The state's Hudson River Estuary research program is one of dozens across the nation in which environmentalists and scientists are using RFID tags, sonic transmitters, antennae, GPS, video, phones and other technology to study underwater ecosystems." Source: informationweek.com