September 2000 SHORT-FINNED PILOT WHALE (Globicephala macrorhynchus): Western North Atlantic Stock

• Main Authors: Stock Definition, Geographic Range
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Reeves; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.294.5781; http://www.nmfs.noaa.gov/pr/pdfs/sars/ao2000whps-wn.pdf

There are two species of pilot whales in the Western Atlantic: the Atlantic or long-finned pilot whale, Globicephala melas, and the short-finned pilot whale, G. macrorhynchus. These species are difficult to identify to the species level at sea; therefore, some of the descriptive material below refers to Globicephala sp. and is identified as such. The species boundary is considered to be in the New Jersey to Cape Hatteras area. Sightings north of this area are likely G. melas. The short-finned pilot whale is distributed worldw ide in tropical to warm temperate waters (Leatherwood and Reeves 1983). The northern extent of the range of this species within the USA Atlantic Exclusive Econo mic Zone (EEZ) is generally thought to be Cape Hatteras, North Carolina (Leatherwood and Reeves 1983). Sightings of these animals in USA Atlantic EEZ occur primarily within the Gulf Stream [Southeast Fisheries Science Center (SEFSC) unpublished data], and prim arily along the continental shelf an d contine ntal slope in the northern Gulf of Mexico (Mullin et al. 1991; SEFSC unpublished data). There is no information on stock differentiatio n for the A tlantic population. POPULATION SIZE An abundance of 9,800 (CV=0.34) for Globicephala 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 modified direct duplicate method (Palka 1995) that accoun ts for school size bias and g(0), the probability of detecting a group on the track line. Aerial data were not corrected for g(0). An abundance of 4,724 (CV=0.61) for Globicephala sp. was estimated from a shipboard line transect sighting survey conducted between 8 July and 17 August 1998 that surveyed 5,570 km of track line in waters Figure 1. Distribution of pilot whale sightings from NEFSC and SEFSC shipboard and aerial surveys during the summer in 1990-1998. Isobaths are at 100 ...