Researchers Use Underwater Robots to Track Sharks in Real Time

The University of Delaware has been engaged in an innovative project using a specially equipped glider called the Oceanographic Telemetry Identification Sensor (OTIS) to follow sand tiger sharks that were previously tagged with transmitters. The glider has found tagged sharks and reported their location in real time. OTIS is a remote-controlled device that looks like a yellow torpedo and normally darts through the ocean to sample water conditions. Oliver outfitted the apparatus with acoustic receivers that can recognize signals given off by the sharks' transmitters as they travel through coastal waters, rapidly reporting the encounters. The technology allows the course of OTIS to be changed to follow the sharks and test the water surrounding them. Sharks were initially found on Oct. 10, and OTIS doubled back to again locate the sharks. The approach will help scientists follow where the sharks are going more quickly than conventional tracking techniques. Sand tigers are the largest commonly occurring shark in Delaware's bay and coastal waters, serving as Delaware Bay's apex predator and playing a key role in the ecological balance of the region. Sand tigers populations have seen a decline and were listed in 1997 as a species of concern by the National Marine Fisheries Service. The research involves three different types of tags. One is an acoustic transmitter that "pings" receivers while passing by a set of 70 devices situated mostly in Delaware Bay, with a few along the Atlantic coast. The team is also using 34 pop-off satellite archival tags, which store data on the sharks' journeys for one year and then automatically release from the animal to dispatch a location signal for retrieval from the water. The newest type of tag is called a VEMCO mobile transceiver (VMT), a larger tag that both transmits and receives information to communicate its location and listen for the pings of other sharks, fish or marine mammals outfitted with acoustic tags.