Supervisor: Dr. Andrew Trites
Education: BSc – Hons (University of Victoria); MSc – Zoology (University of British Columbia)
Research Interests: harbor porpoise (Phocoena phocoena)
Research Area: British Columbia
Foraging behaviour and reproductive season habitat selection of northeast Pacific porpoises
Behavioural observations are fundamental to understanding and defining the habitat needs of animals. I compiled the behavioural repertoires reported for harbour (Phocoena phocoena) and Dall’s porpoise (Phocoenoides dalli) by classifying the life processes of phocoenids into 12 descriptive categories. This range-wide review revealed complex sexual and social behaviours, similar foraging behaviours and breeding site fidelity, as well as differences in habitat selection between these two northern hemisphere species. I also conducted a fine-scale field study of harbour porpoise foraging behaviour at two sites in Juan de Fuca Strait (British Columbia) using point transect survey data (2007–2008), and platforms of opportunity data (1995–1996, 1998–2008) to determine the physical conditions under which harbour porpoise foraged and the extent to which they displayed specialised behaviours. I examined harbour porpoise presence, density and group sizes relative to tidal currents, tidal variation, lunar phase, lunar position, solar position, diurnality, seasonality and presence of conspecifics—and found that greater numbers of harbour porpoise occurred on the ebb current during the spring tides. Numbers of porpoise increased three-fold between April and October, when calves and high-energy behaviours were also more prevalent. To identify porpoise breeding habitat in the inland waters of southern British Columbia and northwestern Washington, I used systematically and opportunistically collected sightings of harbour and Dall’s porpoise (1991–2008), and compared group sizes and frequency of occurrences for both species relative to bathymetry and tidal speeds.
Overall, I found that both species selected bathymetrically differentiated habitats that were characterized by high rates of tidal mixing (with harbour porpoise preferring regions ≤100 m, and Dall’s porpoise preferring 151 – 250 m). Spatial analysis identified two separate areas that may be species-specific breeding habitats—the first to be identified for either species in this region. In summary, harbour porpoise maintained stable group sizes and used tidally well-mixed foraging sites on a temporary but predictable basis. Dall’s porpoise were associated with these same areas, but habitat partitioning associated with differences in bathymetry occurred in important breeding areas that may account for the coastal parapatric distribution of these two high trophic level predators.
- Hall, A. 2010. Marine Mammals. Book Chapter in A Natural History Guide of the Victoria Area. Victoria Natural History Society. In Review.
- Hall, A. 2009. Management Plan for the Pacific Harbour Porpoise (Phocoena phocoena) in Canada [Proposed]. Species at Risk Management Series. Management Plan Series. Fisheries and Oceans Canada, Ottawa. Vi+ 53pp.
- Hall, A. 2008. Sharks of the Pacific Northwest: Including Oregon, Washington, British Columbia, and Alaska. Book Review in BC Studies – The British Columbian Quarterly. Number 156/157.
- Hall, A. 2008. Basking Sharks: The Slaughter of BC’s Gentle Giants and Whales and Dolphins of the North American Pacific. Book Reviews in BC Studies – The British Columbian Quarterly. Number 159.
- Hall, A. 2008. The State of the Pacific North Coast Integrated Management Area. The David Suzuki Foundation. 148pp.
- Williams, R., Hall, A., and Winship, A. 2008. Sustainable limits to anthropogenic mortality of small cetaceans in coastal waters of British Columbia. Canadian Journal of Fisheries and Aquatic Sciences. 65(9): 1867-1878.
- Hall, A.M. 2004. Seasonal Abundance, Distribution and Prey Species of Harbour Porpoise (Phocoena phocoena)
in Southern Vancouver Island Waters. In Department of Zoology. University of British Columbia, Vancouver,
B.C. 109 pages PDF
- Hall, A., Ellis, G., Trites, A.W. 2002. Harbour Porpoise Interactions with the 2001 Selective Salmon Fisheries
in Southern British Columbia and License Holder Reported Small Cetacean By-Catch. Selective
Salmon Fisheries Science Program Report. Fisheries and Oceans Canada.
- Krebs, C.J., Bredesen, E., Coombs, A., Daniel, R.,de Graf, R., Elz, A., Hall, A., Hooper, L., Hoover, T., Janmaat,
A., Mehranvar, L., Rubidge, E., Slooten, G., Tamkee, P., Welstead, K. 2001. Graphical Presentation of Data.
Bulletin of the Ecological Society of America. 82(4): 247-248.