In the 1940s, harbor porpoise were among the most frequently sighted cetaceans in Puget Sound, but by the early 1970s they had all but disappeared. Their numbers have since increased, but they remain a Species of Concern in the state of Washington. A new in-depth species profile looks at the status of harbor porpoise in the Salish Sea, and brings together some of the most comprehensive information to-date about their regional ecology and behavior. The profile was prepared by Jacqlynn Zier and Joe Gaydos of the SeaDoc Society for inclusion in the Encyclopedia of Puget Sound.