ESR SPECIAL PrePrint (2009) - Abstract

ABSTRACT: Studies of movement patterns and habitat use in cetaceans are often constrained by factors such as ship time, logistics, and the ability to follow individuals over time. Obtaining this information on beaked whales is especially difficult, yet the information is critical to their management and conservation, particularly in light of their susceptibility to naval sonar. To better understand the movements of beaked whales around Hawai‘i, Argos-linked satellite tags were remotely applied to the dorsal fins of 8 Blainville’s beaked whales Mesoplodon densirostris in 2006 and 2008, representing the first time that beaked whales have been tracked by satellite. Transmissions from the tags were received for 15 to 71 d (mean = 48 d). All 8 individuals were tagged west of the island of Hawai‘i, and moved out of the small-boat survey area, also making forays into naval training areas. Despite cumulative straight-line distances moved of up to 2383 km, maximum displacement from tagging location for any individual was only 139 km. Individuals utilized slope waters (mean depth = 1156 m) and remained relatively close to the island (mean distance = 16.9 km). No movements to the east side of the island were documented, despite the availability of similar deep-water habitat. Overall movement patterns suggest that the population is island associated and that individuals exhibit strong site fidelity, both of which increase the susceptibility of this small population to local perturbations.

KEY WORDS: Beaked whale · Mesoplodon densirostris · Argos · Satellite tracking · Mid-frequency active sonar · Site fidelity