Listening to Right Whales

Late in spring 2001, during a calm evening on Cape Cod Bay, PCCS researchers, in collaboration with Christopher Clark at Cornell Laboratory of Ornithology, set out five passive acoustic monitors, or pop-ups, adding a new dimension to right whale research: listening from afar. Sitting at the bottom of the bay, recording continuously for thirty days until they were called back to the surface, the pop-ups collected hundreds of hours of data and verified their potential for right whale conservation.

During the winter of 2001-2002, the process was repeated, as six new pop-ups were set from Race Point to the southwest corner of Cape Cod Bay. By using a series of buoys spread out across the bay, Clark can record how right whales use this habitat, how many are present and when, correlating this information with ongoing aerial and habitat studies conducted by the PCCS. This may give PCCS researchers a better understanding of the relative ambient environment of right whales, while testing the feasibility of passive acoustics for eventual use as near-real-time monitoring of right whale regional patterns and how this relates to shipping and fishing practices. For now, the data is collected and stored within the unit until commanded to release its anchor by researchers using a transponder at the surface. The 17-inch glass spheres enclose microprocessors, hard disks for data storage, circuitry and batteries. Outside the sphere, a microphone collects sounds and passes them on to the interior.

Despite the fact that analysis of right whale sounds recorded last spring is ongoing, preliminary findings reveal large fluctuations in acoustic activity throughout the sampling period of March 8 to April 10, 2001. Many thousands of right whale sounds, sometimes at high rates (e.g., 200-300 call per hour), were recorded. These include contact calls as well as surface active group sounds, slap and gunshot vocalizations. It also includes fin whale sounds (calls and songs) and the sounds of various vessels and machines. Comparisons of right whale acoustic locations and tracks with aerial survey and vessel observation results are just beginning. Buoys will be set out during the spring of 2002.