Revised 12/30/98 STOCK DEFINITION AND GEOGRAPHIC RANGE

• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Arctic Ocean; Bering Sea; Gulf of Alaska; Navarin; Pacific; Killer Whale; Sperm whale; Alaska; Aleutian Islands; Killer whale
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.294.7415; http://www.nmfs.noaa.gov/pr/pdfs/sars/ak1998whsp-pn.pdf

The sperm whale is one of the most widely distributed of any marine mammal species, perhaps only exceeded by the killer whale (Rice 1989). They feed primarily on medium-sized to large-sized squids but may also feed on large demersal and mesopelagic sharks, skates, and fishes (Gosho et al. 1984). In the North Pacific, sperm whales are distributed widely (Fig. 26), with the northernmost boundary extending from Cape Navarin (62EN) to the Pribilof Islands (Omura 1955). The shallow continental shelf apparently bars their movement into the northeastern Bering Sea and Arctic Ocean (Rice 1989). Females and young sperm whales usually remain in tropical and temperate waters year-round, while males are thought to move north in the summer to feed in the Gulf of Alaska, Bering Sea, and waters around the Aleutian Islands. In the winter, sperm whales are typically distributed south of 40°N (Gosho et al. 1984). However, discovery tag data from Figure 26. Approximate distribution of sperm whales in the eastern North Pacific (shaded area). CA/OR WA stock the days of commercial whaling revealed a great deal of east-west movement between Alaska waters and the western North Pacific (Japan and the Bonin Islands), with little evidence of north-south movement in the eastern North Pacific. For example, of several hundred sperm whales tagged off San Francisco (Calif.), none were recovered north of 53 ° in the Gulf of Alaska despite large takes there (B. Taylor, pers. comm., Southwest Fisheries Science Center, P. O. Box 271, La Jolla, CA 92038). Therefore, seasonal movement of sperm whales in the North Pacific is unclear at this time. The following information was considered in classifying stock structure based on the Dizon et al. (1992) phylogeographic approach: 1) Distributional data: geographic distribution continuous though indicates three “somewhat ” discrete population centers (i.e., Hawaii, west coast of the continental United States, and Alaska); 2)