BLAINVILLE’S BEAKED WHALE (Mesoplodon densirostris): Northern Gulf of Mexico Stock

• Main Authors: Stock Definition, Geographic Range
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: POPULATION SIZE; Reeves; North Atlantic; Sowerby's beaked whale
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.294.7341; http://www.nmfs.noaa.gov/pr/pdfs/sars/ao1995whbv-gmxn.pdf

Only three species of Mesoplodon are known, from strandings and/or sightings, to occur in the Gulf of Mexico (Jefferson et al. 1992; Hansen et al. 1995). These are Blainville's beaked whale (M. densirostris), Gervais ' beaked whale (M. europaeus), and Sowerby's beaked whale (M. bidens). The occurrence of Sowerby’s beaked whale in the Gulf of Mexico is considered extralimital because there is only one known stranding of this species in the Gulf of Mexico (Bonde and O’Shea 1989) and because it normally occurs in northern temperate waters of the North Atlantic (Mead 1989). Identification of Mesoplodon species at sea is problematic; therefore, nearly all sightings of these species are identified as beaked whales and may include sightings of Ziphius cavirostris that were not identified as such. Beaked whales were seen in all seasons during recent seasonal GulfCet aerial surveys of the northern Gulf of Mexico (Davis et al., in preparation). Blainville’s beaked whales appear to be widely but sparsely distributed in warm temperate and tropical waters of the world’s oceans (Leatherwood et al. 1976; Leatherwood and Reeves 1983). Strandings have occurred along the northwestern Atlantic coast from Florida to Nova Scotia (Schmidly 1981), and there have been two documented strandings of this species in the northern Gulf of Mexico and one sighting (Jefferson et al. 1992; Hansen et al. 1995). There is no information on stock differentiation.