Seasonal abundance, distribution and prey species of harbour porpoise (Phocoena phocoena) in southern Vancouver Island waters ...

• Main Author: Hall, Anna Marie
• Format: Text
• Language: English
• Published: University of British Columbia 2009
• Subjects: Harbour porpoise; Phocoena phocoena
• Online Access: https://dx.doi.org/10.14288/1.0074879; https://doi.library.ubc.ca/10.14288/1.0074879

Harbour porpoise (Phocoena phocoena) occur year round in the waters of southern British Columbia, but little is known about their seasonal abundance, habitat use and food habits. A systematic vessel-based line transect survey was undertaken to quantitatively assess seasonal trends in harbour porpoise abundance and distribution within the Canadian waters of Juan de Fuca and Haro Straits (08 September 2001 to 31 August 2002). These data were supplemented with opportunistic counts (1995-1996, 1998-2001) and stomach contents from post-mortem stranded porpoise (1998-2001). The study area encompassed 805.3 km2 with a total transect length of 1838.4 km. Data collection was restricted to Beaufort 0 and 1 sea conditions, and abundance was estimated using DISTANCE 3.5 software. Encounter rates observed from April to October were significantly higher than from the rest of the year. Seasonal abundance estimates (corrected for visual radial distance estimation) ranged from a high of 673 porpoise from April-October ...