DWARF SPERM WHALE (Kogia simus): 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=10.1.1.294.8350; http://www.nmfs.noaa.gov/pr/pdfs/sars/ao2000whds-wn.pdf

The dwarf sperm whale (Kogia simus) appears to be distributed worldwide in temperate to tropical waters (Caldwell and Caldwell 1989). There are no stranding records for the east Canadian coast (Willis and Baird 1998). Sightings of these animals in the western North Atlantic occur primarily along the continental shelf edge and over the deeper waters off the continental shelf (Hansen et al. 1994; NMFS unpublished data). Dwarf sperm whales and pygmy sperm whales are difficult to distinguish and sightings of either species are often categorized as Kogia sp. There is no information on stock differentiation for the Atlantic population. In a recent study using hematological and stable-isotope data, Barros et al. (1998) speculated that dwarf sperm whales may have a more pelagic distribution than pygmy sperm whales, and/or div e deeper during feeding b outs. POPULATION SIZE An abundance of 115 (CV=0.61) for Kogia sp.was estimated from a line transect sighting survey conducted during July 6 to September 6, 1998 by a ship and plane that surveyed 15,900 km of track line in waters north of Maryland (38 ° N) (Figure 1; Palka et al. in review). Shipboard data were analyzed using the m odified direct duplicate method (Palka 1995) that accounts for school size bias and g(0), the probab ility of detecting a group on the track line. Aerial data were not corrected for g(0). An abundance of 421 (CV=0.55) for Kogia sp. was estimated from a shipboard line transect sighting