An experimental tag-based tracking technology is being tested as a way of tracking whales and gathering information about how they live.
Two tests using the tagging devices just wrapped up off the coast of New England, according to Peter Tyack, a senior scientist at the Woods Hole Oceanographic Institution. The testing took place at the Massachusetts Stellwagen Bank National Marine Sanctuary and off the coast of Maine.
To track whales, Woods Hole engineer Mark Johnson devised a silicon tag, called a D Tag, that's about the size of a PC mouse and can record sound at 192 MHz. It has a pressure sensor that measures water depth a microprocessor, hydrophone and nonacoustic sensors that can sample environmental data 50 times a second. That's fast enough to record fluke strokes and feeding movements, Tyack said.
Tyack said the sensors are useful because the only time a whale can be observed is when it comes up to breathe or eat. "What's frustrating about whales and tracking their behavior is that we only see them when they come to the surface, only a tiny fraction of the time," he said. "Then the whales goes down deep and you can't see anything about its behavior or what depth it's at."
The D Tags are placed on the whale via suction cups and remain in place for about a day until they release as designed. After the tag -- which is tough enough to be used on deep diving sperm whales -- comes free, a special foam floats it to the surface and an embedded radio transmitter acts as a beacon so it can be retrieved.
The tag has internal flash memory with up to 12GB of capacity to store any information gathered on the animal. That data is then extracted via a custom-built high-bandwidth wireless infrared link and analyzed in a Matlab application. The software is designed to allow marine engineers to manipulate the data and study any patterns that emerge.
The two experiments that Tyack worked on in July included a humpback whale tagging project at Stellwagen Bank, some 30 miles off the coast of Massachusetts. The sanctuary is a veritable mecca of whale activity. The immediate goal was to correlate humpback whale activity with information on shipping movements, with the long-term plan to meld the information on whale activity and maritime craft movement and speed. That way, ships can be alerted to avoid the whales in an effort to prevent dangerous collisions.
The researchers were able to tag about eight whales in a week during the experiment, said Tyack.
In June and July, the D Tags were also used to try to tag right whales in a project funded by the National Fish and Wildlife Foundation and by the Maine Department of Marine Resources. In Maine, whales aren't just threatened by boat collisions; fishermen also put out gear in which whales can become entangled in. The Maine effort was designed to gather data on how close to the bottom right whales feed to help design whale-safe gear, said Tyack.
That effort will resume next year because the only right whales that appeared this summer were mothers and their calves, which were considered off-limits. "We'll have to do it again next year to get detailed behavior," Tyack said.