Movements and Spatial Use of Odontocetes in the Western Main Hawaiian Islands: Results of a Three-Year Study Off O'ahu and Kaua'i

Abstract

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. SPONSOR/MONITOR'S REPORTMonterey, CA 93943-5122 NUMBER(S)NPS-OC-14-001CR DISTRIBUTION / AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTESThe views expressed in this report are those of the authors and do not reflect the official policy or position of the Department of Defense or the US Government. ABSTRACTUnderstanding the impacts of anthropogenic activities on animal populations requires knowledge of their population structure, sizes, and ranges. In Hawaiian waters this type of basic information has been lacking or is restricted to areas where conditions have been more favorable to research efforts, namely the eastern main Hawaiian Islands. As part of an effort to reduce uncertainty regarding the population structure, range, and abundance of odontocetes in the western main Hawaiian Islands, and to help inform Navy impact assessments, we undertook small-boat based research efforts off O'ahu (2010) and Kaua'i (2011Kaua'i ( & 2012. A variety of field methods were used, including photo-identification, collection of biopsy samples for genetic studies, and satellite tagging. There were 191 odontocete sightings, 183 identified to species. 102 biopsy samples were collected from 7 species. 30 satellite tags were deployed on 5 species: pygmy and false killer whales, bottlenose and rough-toothed dolphins, and short-finned pilot whales. Our efforts substantially increased what is known in particular about the movements and habitat use of these 5 species of odontocetes in the western main Hawaiian Islands. SUBJECT TERMSMarine mammals, western Hawaiian Islands, odontocetes, population structure, population size, population range, photo identification, biopsy sampling, satellite tagging, pygmy killer whale, false killer whale, bottlenose dolphin, rough-toothed dolphin, short-finned pilot whale.

Assessment of Modeled Received Sound Pressure Levels and Movements of Satellite-Tagged Odontocetes Exposed to Mid-Frequency Active Sonar at the Pacific Missile Range Facility: February 2011 Through February 2013

“…During these efforts, data were obtained from 23 tagged individuals of four species: short-finned pilot whales, bottlenose dolphins, rough-toothed dolphins, and false killer whales (Baird et al 2013a(Baird et al , 2013c; Table 1). While PAM acoustic recordings have been made for all of the SCCs since 2011, overlap with tag data is variable and in some cases limited recorded data is available before the SCCs.…”

“…Based on photo-identification and genetics there appears to be a small population of bottlenose dolphins resident to the islands of Kaua'i and Ni'ihau (Baird et al 2009;Martien et al 2011), and this population is recognized by the National Marine Fisheries Service as a discrete stock (Carretta et al 2011). The individual TtTag010 had not been previously photo-identified off the island, and no other individuals in the group it was tagged in were photographed (Baird et al 2013c). However, 3 days after it was first tagged, this individual appeared to repeatedly associate with another tagged bottlenose dolphin that was known to be part of the resident islandassociated population (see Figure 6 in Baird et al 2013a).…”

“…Details on field methods are available in Baird et al (2013aBaird et al ( , 2013c. Four of the five efforts were timed to coincide with SCC training events, with the first effort starting at the end of the February 2011 SCC, and efforts starting before the August 2011, February 2012, and February 2013 SCCs.…”

“…Locations of tagged individuals were estimated using the Argos Data Collection and Location System with a least-squares method and assessed for plausibility using the Douglas Argos-Filter version 8.2 (Douglas et al 2012) to remove unrealistic locations; this approach follows protocols applied previously (Schorr et al 2009;Baird et al 2010Baird et al , 2011aBaird et al , 2013c. This filter includes four user-defined variables: 1) Maximum redundant distance-consecutive points separated by less than a defined distance are kept by the filter because Argos location errors rarely occur in the same place, thus nearby temporally consecutive points are assumed to be self confirming;…”

“…In recent years, boat-based studies involving deployment of Low-Impact Minimally Percutaneous External-electronics Transmitter (LIMPET) satellite tags on odontocete cetaceans on and around PMRF, combined with real-time PAM (in conjunction with the Marine Mammal Monitoring on Navy Ranges project) to increase boat-based encounter rates, have allowed for assessments of habitat use and range of several different odontocete species (Baird et al 2013a(Baird et al , 2013c. Information obtained from these studies have provided evidence for resident, islandassociated populations of rough-toothed dolphins (Steno bredanensis), common bottlenose dolphins (Tursiops truncatus) and short-finned pilot whales (Globicephala macrorhynchus) off Kaua'i and Ni'ihau, with each species varying in movement patterns and habitat use (Baird et al 2008(Baird et al , 2009(Baird et al , 2013a(Baird et al , 2013cMartien et al 2011). …”