Acoustical Deterrence Of Harbor Porpoises

Students have worked to develop an acoustic deterrent for reducing the incidental take of harbor porpoises ("Phocoena phocoena") by sink-gillnets in the Gulf of Maine. They designed an autonomous sound signal device to be attached to sink- gillnets. The signal is broadcast for one millisecond at 500 millisecond intervals. At this rate the expected battery life is 72 hours; easy batter maintenance and access are provided. The electronics are encased in a rugged, corrosion-resistant housing of PVC, stainless steel, brass, and urethane.