Sightings of Dwarf (Kogia sima) and Pygmy (K. breviceps) Sperm Whales from the Main Hawaiian Islands

Abstract

Sightings of dwarf (Kogia sima) and pygmy (K. breviceps) sperm whales in Hawaiian waters have only rarely been reported. As part of boat-based surveys of odontocete cetaceans around the main Hawaiian Islands between 2000 and 2003, Kogia were observed on 18 occasions. Kogia were sighted most frequently in deeper portions of the study area (mean depth, 1,425 m) and in calm sea conditions (mean Beaufort sea state, 0.8). Thirteen of the 14 groups identified to species were dwarf sperm whales, the sixth most common species of odontocete documented around the main Hawaiian Islands. One group of six dwarf sperm whales containing two mother-infant pairs did not dive for more than a few minutes at a time. Most groups were difficult to approach, but photographs of several individual dwarf sperm whales showed distinctive marks on the dorsal fins, demonstrating that individual photo-identification is possible with this species.