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 persistent use of a very small, bathy-metrically unique ocean area make it vulnerable to human disturbance.