Studies of Beaked Whales in Hawaii: Population Size, Movements, Trophic Ecology, Social Organization and Behavior

摘要

Ongoing field studies of Cuvier's, Ziphius cavirostris, and Blainville's beaked whales, Mesoplodon densirostris, around the main Hawaiian Islands address aspects of the biology and ecology of these species. These include: (1) diving behaviour, using suction-cup attached time-depth recorders (Baird et al., 2006a, b); (2) population sizes, using capture-recapture methods with photo-identification data; (3) habitat use, using GIS analyses of effort and sighting data; (4) trophic ecology, using stable isotope analyses of biopsy samples, genetic determination of prey from faecal samples, and direct collection of prey items; (5) site fidelity/movements, through long-term photoidentification, short-term VHF radio tracking, and medium-term satellite tagging; (6) social organisation, through analyses of associations based on photo-ID data and observations of behavioural interactions; and (7) population structure, through genetic analyses of biopsy samples, satellite tagging, and photo-identification. Directed survey effort around all the main Hawaiian Islands has been ongoing since 2000, with 38,434 km of trackline surveyed through 2006. Cuvier's beaked whales are the seventh-most frequently encountered odontocete (1.27 sightings per 1,000 km off the island of Hawai'i), representing 3.4% of all odontocete sightings. Blainville's beaked whales are tied for the eight-most frequently encountered odontocete (0.86 sightings per 1, 000 km off the island of Hawai'i), representing 2.8% of all odontocete sightings.