Lien, J., C. Hood, D. Pittman, P. Ruel, D. Borggaard, C. Chisholm, L. Wiesner, T. Mahon, and D. Mitchell In: R.A. Kastelien, J.A. Thomas, and P.E. Nachtigall, eds. Sensory Systems of Aquatic Mammals De Spil Publishers, Woerden, The Netherlands ISBN 90-72743-05-9 Gillnets equipped with acoustic pingers caught only one harbor porpoise (Phocoena phocoena) compared to 42 caught in control nets off of New Hampshire, USA. Alarms sounds are above groundfish hearing and are not expected to affect fish catch.