HARBOR PORPOISE ( PHOCOENA PHOCOENA ) ABUNDANCE IN ALASKA: BRISTOL BAY TO SOUTHEAST ALASKA, 1991‐1993

• Published in: Marine Mammal Science
• Main Authors: Dahlheim, M., York, A., Towell, R., Waite, J., Breiwick, J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2000
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Bering Sea; Dixon Entrance; Kodiak; Phocoena phocoena; Alaska
• Online Access: http://dx.doi.org/10.1111/j.1748-7692.2000.tb00902.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1748-7692.2000.tb00902.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1748-7692.2000.tb00902.x

A bstract Between 1991 and 1993, Alaska harbor porpoise ( Phocoena phocoena ) abundance was investigated during aerial surveys throughout much of the coastal and offshore waters from Bristol Bay in the eastern Bering Sea to Dixon Entrance in Southeast Alaska. Line‐transect methodology was used, and only those observations made during optimal conditions were analyzed. Survey data indicated densities of 4.48 groups/100 km 2 , or approximately 3,531 harbor porpoises (95% C. I. 2,206‐5,651) in Bristol Bay and 0.54 groups/100 km 2 , or 136 harbor porpoises (95% C. I. 11‐1,645) for Cook Inlet. Efforts off Kodiak Island resulted in densities of 1.85 groups/100 km 2 , or an abundance estimate of 740 (95% C. I. 259‐2,115). Surveys off the south side of the Alaska Peninsula found densities of 2.03 groups/100 km 2 and an abundance estimate of 551 (95% C. I. 423‐719). Surveys of offshore waters from Prince William Sound to Dixon Entrance yielded densities of 4.02 groups/100 km 2 and an abundance estimate of 3,982 (95% C. I. 2,567‐6,177). Combining all years and areas yielded an uncorrected density estimate of 3.82 porpoises per 100 km 2 , resulting in an abundance estimate of 8,940 porpoises (CV = 13.8%) with a 95% confidence interval of 6,746‐11,848. Using correction factors from other studies to adjust for animals missed by observers, the total number of Alaska harbor porpoises is probably three times this number.