Movements and spatial use of satellite tagged odontocetes in the western main Hawaiian Islands: results of field work undertaken off O'ahu in October 2010 and Kaua'i in February 2011

Abstract

In the first year of a 3-year effort, surveys were made of odontocetes off Oahu and Kauai to examine spatial use and residency patterns in the western half of the Hawaii Range Complex using satellite tags, as well as obtaining individual identification photographs and biopsy samples for assessment of population identity and structure. 43 groups of 10 odontocete species were encountered, 15 satellite tags were deployed on 3 species, 39 genetic samples of 6 species and over 23000 photographs were obtained. Satellite tags were deployed on individuals in 2 groups of pygmy killer whales. Habitat use of the 2 groups differed substantially, and may be related to residency of the groups. Most individuals in one group had been previously photo-identified off Oahu. This group spent most of its time along the shores of Oahu, primarily in water <1000 m. 17 individuals in the other group had been photo-identified, but none previously off Oahu. The tagged individual from this second group ranged more extensively off Oahu than individuals from the first group, and spent most of its time in water >1000 m. Short-finned pilot whales were also tagged. Again, considerable variation in movement patterns and habitat use were observed: some groups remained close to the tagging area, suggesting residency; others ranged widely over varying depths. The differing ranging patterns may have implications for exposure and responses to Navy exercises.