Like other odontocetes, harbor porpoises use echolocation for feeding and orientation. The dominant components of harbor porpoise echolocation signals are narrowband, high-frequency (ultrasonic) clicks within 110-150kHz. This is consistent with their hearing, with best sensitivity between 100 and 120 kHz. Click duration ranges from about 60 µs to 300 µs and the clicks are usually emitted in a series called a click train. Harbor porpoises produce intense click trains where the inter-click interval within a train ranges between 20 and 80 msec. This can decrease to less than 2 msec, especially when the animal is nearing its target: i.e., a fish. At this time the click train will actually sound more like a “buzz”.Due to the coastal distribution of the harbor porpoise, conflicts arise between the species and humans. The primary human-induced threat to the harbor porpoise is bycatch in commercial fishing gear. Several harbor porpoise populations are in decline, at least partly as a result of entanglement in gillnet gear. In New England and mid-Atlantic waters of North America, attempts are being made to reduce harbor porpoise bycatch. The Harbor Porpoise Take Reduction Plan (HPTRP) is a suite of U.S. federal regulations that requires fishermen to use underwater acoustic alarms (pingers) on their nets and modify fishing gear configurations to reduce entanglement. The plan also implements area closures where gillnet fishing is prohibited. Conservation plans for harbor porpoises in European waters are also being developed by the Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS).
- "Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas (ASCOBANS)" (Link)
- Akamatsu, T., Teilmann, J., Miller, L., Tougaard, J., Dietz, R., Wang, D., Wang, K., Siebert, U., Naito, Y. 2007, "Comparison of echolocation behaviour between coastal and riverine porpoises." Deep-Sea Research II. 54: 290-297.
- Bjorge, A., and Tolley, K. 2002, "Harbor Porpoise." In: Encyclopedia of Marine Mammals. William F. Perrin, Bernd Wursig, J.G.M. Thewissen, editors. Academic Press. San Diego. Pp 549-551.
- Carlstrom, J. 2005, "Diel variation in echolocation behavior of wild harbor porpoises." Marine Mammal Science. 21(1): 1-12.
- NOAA Fisheries, Northeast Regional Office, "Harbor Porpoise Take Reduction Plan (HPTRP)" (Link)
- Villadsgaard, A., Wahlberg, M., and Tougaard, J., "Echolocation signals of wild harbour porpoises, Phocoena phocoena" The Journal of Experimental Biology. 210: 56-64.
- Wynne, K., and Schwartz, M. 1999, "Guide to Marine Mammals and Turtles of the US Atlantic and Gulf of Mexico." Rhode Island Sea Grant. Pp 80-81.
- Scripps Institution of Oceanography, "Voices in the Sea." (Link)