Report of the International Whaling Commission (1990)


Dorsal fin photographs of Dall’s porpoise, Phocoenoides dalli, were taken in northern Puget Sound, Washington in order to assess the feasibility of using photo-identification techniques in studies of this species. Twenty percent of the photographs were suitable for identification. Thirty-five porpoises were identified using the left side of the dorsal fin, and 28 porpoises were identified using the right. The techniques were applied to investigate group structure and calculate abundance estimates for the study area. Resightings of identified animals were infrequent, and few associations between animals were observed within the study area. Average distance between resightings of individuals was 5.4km. Abundance was assessed through mark-recapture analyses and direct counts of identified animals.