Dukane Corporation and Burnett Electronics of San Diego, California later obtained a license from NASA, further improving on the beacon design. Dukane has sold well over 100,000 units since. Thanks to a team from Dukane, an underwater acoustic pinger is finding new duty in safeguarding the harbor porpoise. At stake was finding a balance between regulatory rulings, including the Marine Mammal Protection Act, as well as the livelihood of a New England fishing community. During a test at the University of New Hampshire Ocean Engineering Laboratory, the pinger is dropped to 10 feet below the surface of the water.
Scientists then measure the sound pressure waves and frequencies at varying distances.
A large-scale field experiment off the coast of New Hampshire in autumn 1994 gauged the effectiveness of acoustic pingers in reducing incidental mortality of harbor porpoises in sink gill nets. The study was carried out by the New England Aquarium, along with researchers from Woods Hole Oceanographic Institution, the New Hampshire Commercial Fishermens Association and the University of New Hampshire's Department of Ocean Engineering. Broadcasting a signal well within the hearing range of harbor porpoises, the pingers provided warning as to position of the sink gill nets, alerting the mammals to help them avoid net entanglement. The study found that the use of acoustic alarms appears to hold considerable promise in reducing the number of harbor porpoises killed in sink gill nets in the Gulf of Maine. Following the promising results, Dukane has put in place a manufacturing program to produce the low-cost NetMark 1000 pinger.