 Populations are denser close to continental shelves and canyons . Sperm whales are usually found in deep , off @-@ shore waters , but may be seen closer to shore , in areas where the continental shelf is small and drops quickly to depths of 310 to 920 metres ( 1 @,@ 020 to 3 @,@ 020 ft ) . Coastal areas with significant sperm whale populations include the Azores and Dominica . In Asian waters , whales are also observed regularly in coastal waters in places such as Commander and Kuril Islands , Shiretoko Peninsula , off <unk> , vicinity to Tokyo Bay and Boso Peninsula to Izu and Izu Islands , Volcano Islands , Yakushima and <unk> Islands to Ryukyu Islands , Taiwan , Northern Mariana Islands , and so forth . Historical catch records suggest there could have been smaller aggression grounds in the Sea of Japan as well . 
