PYGMY SPERM WHALE (Kogia breviceps): Western North Atlantic Stock

• Main Authors: Stock Definition, Geographic Range
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2005
• Subjects: Barros; Caldwell; North Atlantic; Sperm whale
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.294.6763; http://www.nmfs.noaa.gov/pr/pdfs/sars/ao2005whpy-wn.pdf

The pygmy sperm whale (Kogia breviceps) appears to be distributed worldwide in temperate to tropical waters (Caldwell and Caldwell 1989). Sightings of these animals in the western North Atlantic occur in oceanic waters ( Mullin and Fulling 2003; SEFSC unpublished data). Pygmy sperm whales and dwarf sperm whales (K. sima) are difficult to differentiate at sea (Caldwell and Caldwell 1989, Wursig et al. 2000), and sightings of either species are often categorized as Kogia sp. There is no information on stock differentiation for the Atlantic population. Duffield et al. (2003) propose using the molecular weights of myoglobin and hemoglobin, as determined by blood or muscle tissues of stranded animals, as a quick and robust way to provide species confirmation. Using hematological as well as stable-isotope data, Barros et al. (1998) speculated that dwarf sperm whales may have a more pelagic distribution than pygmy sperm whales, and/or dive deeper during feeding bouts. Diagnostic morphological characters have also been useful in distinguishing the two Kogia species (Barros and Duffield 2003), thus enabling researchers to use stranding data in distributional and ecological studies. Specifically, the distance from the snout to the center of the blowhole in proportion to the animal’s total length, as well as the height of the dorsal fin, in proportion to the animal’s total length, can be used to differentiate between the two Kogia species when such measurements are obtainable (Barros and Duffield 2003). POPULATION SIZE Total numbers of pygmy sperm whales off the