Residency and abundance of sperm whales (Physeter macrocephalus) in the Bleik Canyon, Norway

Sperm whales (Physeter macrocephalus) are widely distributed in the Norwegian Sea and feeding aggregations occur. One of these aggregations is in the Bleik Canyon, close to shore in Norway, where the present study was performed. The study used a whale safari company as a platform from which to conduct a photo-identification study of male sperm whales. Data for this study was comprised of a total of 3856 images from 22 seasons (1987-2010) of whale-watching tours. In total, 411 individuals were identified. This study supports the results from previous photo-identification studies in the Bleik Canyon and confirms the presence of both transient and resident male sperm whales in the Bleik Canyon. These results suggest that the sperm whale group(s) found there are a loose feeding aggregation and not a closed population. Total residence time varied between one day and 14 years, although most individuals were only seen in one or two years. The number of sighted whales fluctuated between years, from eight to 77 individuals. No trend in the number of sighted whales was found. The estimated size of the feeding aggregation in the Bleik Canyon also fluctuated between years, from 11 to 116 individuals, with no trend evident.