There are two harbour porpoise populations in Canada. The Pacific Ocean population is found in shelf-waters throughout the province, year round. They dwell primarily over continental shelves as the population density appears to be lower in deep-water basins. True to their name, they are also known to spend time in bays and harbours during summer.

They tend to stay in areas close to small schooling fish prey, but they have been known to move quickly between areas of suitable habitat, separated by tens, or even thousands of kilometres. Harbour porpoises are rarely seen in highly developed areas, leading us to believe that they avoid human activity.

Rarely reaching lengths greater than 1.7 metres, harbour porpoises weigh an average of 90 kilograms. Females grow more quickly and are larger than males. Porpoises have rounded heads and a small triangular dorsal fin at the middle of their backs. Its mottled greyish-white sides fade to almost white along its belly, helping it blend well into the marine environment. A black 'cape' extends over the back and sides of the harbour porpoise. Some may also have dark patches on the face. There is no difference in coloring between males and females; however calves are usually darker than adults. The harbour porpoise is a short-lived, shy species; there are no estimates of the annual survival rates of the harbour porpoise but it's understood that their lifespan is relatively short as few live to the age of 20.