242 Abstract—Abundance of harbor por- Temporal changes in abundance of harbor poise (Phocoena phocoena) was es- timated from data collected during porpoise (Phocoena phocoena) inhabiting the vessel surveys conducted through- out the inland waters of Southeast inland waters of Southeast Alaska Alaska. Line-transect methods were used during 18 seasonal surveys Marilyn E. Dahlheim (contact author)1 spanning 22 years (1991–2012). Es- 1, 2 timates were derived from summer Alexandre N. Zerbini surveys only because of the broader Janice M. Waite1 spatial coverage and greater number Amy S. Kennedy1 of surveys during this season than during other seasons. Porpoise abun- Email address for contact author:
[email protected] dance varied when different periods were compared (i.e., 1991–1993, 1 2006–2007, and 2010–2012); how- National Marine Mammal Laboratory ever, persistent areas of high por- Alaska Fisheries Science Center poise densities occurred in Glacier National Marine Fisheries Service, NOAA Bay and Icy Strait, and off the town 7600 Sand Point Way NE of Wrangell and Zarembo Island. Seattle, Washington 98115-6349 Overall abundance of harbor por- 2 Cascadia Research Collective poise significantly declined from the 218 ½ West Fourth Avenue early 1990s (N=1076, 95% confidence Olympia, Washington 98501 interval [CI]=910–1272) to the mid- 2000s (N=604, 95% CI=468–780). This downward trend was followed by a significant increase in the early 2010s (N=975, 95% CI=857–1109) when abundance rose to levels simi- Harbor porpoise (Phocoena phocoena) the Southeast Alaska stock—occur- lar to those observed 20 years ear- are distributed throughout Alaska ring from Dixon Entrance (54°30′N; lier.