October 2007 DWARF SPERM WHALE (Kogia sima): Western North Atlantic Stock

• Main Authors: Stock Definition, Geographic Range
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Barros; Caldwell; Willis; North Atlantic; Sperm whale
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.174.4376; http://www.nefsc.noaa.gov/publications/tm/tm205/pdfs/54DwarfSpermW.pdf

The dwarf sperm whale (Kogia sima) appears to be distributed worldwide in temperate to tropical waters (Caldwell and Caldwell 1989; McAlpine 2002). Sightings of these animals in the western North Atlantic occur in oceanic waters (Mullin and Fulling 2003; NMFS unpublished data), although there are no stranding records for the east Canadian coast (Willis and Baird 1998). Dwarf sperm whales and pygmy sperm whales (K. breviceps) 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. Diagnostic morphological characters have 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; Handley 1966) 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