Population analysis of northern bottlenose whales in the Gully, Nova Scotia

Northern bottlenose whales (Hyperoodon ampullatus) are consistently found through the year in the Gully a prominent submarine canyon on the edge of the Scotian Shelf. Individuals were photographically identified during field studies between 1988 and 1995. About 70% of the population is identifiable, and 29% have markings which persist reliably over periods of years. A mark-recapture analysis of photographic individual identifications collected between 1988 and 1995 indicates that the population using the Gully numbers about 230 animals (approximate 95% confidence interval 160-360). The rate of mortality plus emigration plus mark change (in animals with reliable long-term marks) is about 12% per year, although this estimate has wide and uncertain confidence limits. Members of the Gully population, which includes calves and mature males, are shorter than animals caught: off Labrador. The small size of the Gully population and its persist ent use of a very small, bathymetrically unique ocean area make it vulnerable to human disturbance.