Right whales are talking, but is anyone listening? Research planned off the Georgia coast this winter may help scientists determine whether whale calls can be used to protect endangered right whales.
Collisions with ships are a leading cause of North Atlantic right whale deaths. With right whale numbers estimated at only about 400, the loss of one breeding female can affect the species. For more than 20 years, the primary way of reducing ship strikes has been through aerial surveys, which are costly, dangerous and ineffective at night and in bad weather. Thanks to improvements in technology, another method is coming online – locating whales by their calls.
This method, referred to as passive acoustic detection, uses computerized buoys that listen for right whale calls and immediately report those calls to land using a cellular or satellite telephone link.
Scientists from Cornell University and the Woods Hole Oceanographic Institution recently installed the first full-scale, real-time passive acoustic detection system in Cape Cod Bay. (Check www.listenforwhales.org/ for updates on whales detected.) When a right whale vocalization is detected, certain ships entering Cape Cod Bay are notified and required to slow to 10 knots.
Passive acoustic detection has been proposed as a way to protect right whales in their calving areas along the Georgia and Florida coast. Research has shown that right whales also call in the Southeast, and related projects are in the works, building on years of study in the Northeast. But a central question remains: Do cows with calves vocalize or is it the larger numbers of non-breeding whales that are calling?
Some have speculated that cows with calves may be quieter than other whales, perhaps to avoid attracting predators. If so, passive acoustic detection techniques would be poorly suited to protecting the most valuable demographic component of the population – breeding females.
Biologists from the Georgia Department of Natural Resources, the Florida Fish and Wildlife Conservation Commission and NOAA National Marine Fisheries Service hope to answer this question during the upcoming right whale calving season. They plan to attach temporary recording devices called Bioacoustic Probes or B-Probes on the backs of up to 10 right whale cows with calves.
The probe tags are about a foot long and attach to the whales’ rubbery skin with suction cups. The process sounds deceivingly simple: A whale is approached by boat. The tag is attached to the whale’s back with a handheld pole. The probe records vocalizations and ambient sound for up to 12 hours. Then it pops off and is relocated using a VHF radio receiver.
“While maneuvering the 23-foot tagging boat within 15 feet of a 50-foot-long, 50-ton swimming right whale will certainly be challenging, the biggest challenge will likely be whether or not the tags stay on for the full recording time,” said biologist Clay George, of the DNR’s Wildlife Resources Division. “Right whale calves frequently roll back and forth across their mothers’ backs, which may cause the tags to detach prematurely.”
If successful, the project could help determine whether passive acoustic detection is a viable management option in the Southeast. The project will take place from January through March 2009. Scientists at the Northeast Fisheries Science Center will analyze the acoustic data. The National Oceanic and Atmospheric Administration Marine Fisheries Service and the DNR’s Nongame Wildlife Conservation Fund are providing funding.
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