US Department of Commerce

 

Date of this Version

2011

Comments

Published in MARINE MAMMAL SCIENCE, (2011) 27(4): E332–E337; DOI: 10.1111/j.1748-7692.2010.00458.x

Abstract

Pygmy killer whales (Feresa attenuata) are a rare tropical oceanic odontocete that are normally found close to shore only around oceanic islands (Donahue and Perryman 2009, McSweeney et al. 2009). In the Exclusive Economic Zone (EEZ) surrounding the Hawaiian Islands there is a single stock of pygmy killer whales recognized (Carretta et al. 2010). In the Hawaiian EEZ they are the third-least abundant of the 12 species of delphinids documented, with an estimated abundance of 956 individuals (CV = 0.83; Barlow 2006). Around the island of Hawai‘i a long-term photo-identification study has identified a small population that exhibits high site fidelity (McSweeney et al. 2009). This species is encountered only infrequently (an average of once every 35 d on the water), and thus limited information is available to examine movements based on location records of photo-identified individuals.Only a small number of identification photos have been available from other islands in the main Hawaiian Islands so there has been little ability to assess movements among islands.

As part of a long-term research effort to examine odontocete movements, habitat use, ecology, and abundance (Baird et al. 2008, 2009, 2010), we remotely deployed two dorsal fin attached satellite tags on pygmy killer whales off the island of Hawai‘i in 2008 and 2009, and report here on movements and habitat use of these two individuals. Given the accumulating evidence of multiple discrete populations of other, better studied, species of odontocetes around the main Hawaiian Islands (Chivers et al. 2007, 2010; Baird et al. 2008, 2009; Andrews et al. 2010; Courbis et al.), information on movements of pygmy killer whales is relevant to assessing whether multiple stocks of this species also exist within the Hawaiian EEZ. While the sample size is small, because of the low encounter rate and the usual difficulty in approaching individuals close enough for tagging, it is unlikely we will be able to obtain additional movement data from this species any time soon. Information from the two tags represents the only information available on movements for this species and greatly increases information on habitat use.