A joint project in February 2014 on and around the Pacific Missile Range Facility (PMRF) was carried out utilizing combined passive acoustic monitoring and boat-based field efforts. There were 1,287 kilometers (km) (66.3 hours [hr]) of small-vessel survey effort over the course of the 10-day project, with 44.6 percent of search time (29.6 hr) spent within the PMRF instrumented hydrophone range boundaries. A total of 81.7 hr of acoustic monitoring was undertaken during the field effort. There were 26 sightings of five species of odontocetes, six of which were directed by acoustic detections from the Marine Mammal Monitoring on Navy Ranges (M3R) system. Bottlenose dolphins (Tursiops truncatus) were encountered on eight occasions, spinner dolphins (Stenella longirostris) on seven, short-finned pilot whales (Globicephala macrorhynchus) on five, rough-toothed dolphins (Steno bredanensis) on two, and Blainville’s beaked whales (Mesoplodon densirostris) once. Recordings on the M3R system were made for four species (all but spinner dolphins) to improve species classification for future acoustic monitoring efforts. During the encounters 10,928 photos were taken for individual identification, six biopsy samples were obtained for genetic studies, and 12 satellite tags were deployed on four species – six short-finned pilot whales, two bottlenose dolphins, two rough-toothed dolphins, and two Blainville’s beaked whales (although data were obtained from only one of the two). The Blainville’s beaked whale was tagged off PMRF, but over an eight-day period the tagged animal moved onto the range three times and spent an estimated 20.5 percent of its time on PMRF. The tagged individual remained associated with the island slopes (median depth of locations = 961 meters [m]), and remained within 83 km of the tagging location. Although both of the tagged rough-toothed dolphins remained associated with the islands (median depths of 1,463 and 1,961 m), one moved as far as western O‘ahu, the first movement of a tagged rough-toothed dolphin away from Kaua‘i and Ni‘ihau. Both tagged bottlenose dolphins remained strongly associated with the island of Kaua‘i (median depth of 56 and 88 m) over the tag attachment periods (6 and 13 days, respectively). The six tagged short-finned pilot whales included individuals from three different social clusters, one of which (HIGm0929, tag number GmTag078) had only previously been documented off Hawai‘i Island. HIGm0929 remained primarily in deep water (median = 3,351 m) farther from shore (median distance from shore = 39.9 km), while individuals from the other two social clusters used shallower water (median depths from 1,635 to 2,296 m) closer to shore (median distances from 13.9 to 19.3 km). Probability density analyses of all tag location data obtained for bottlenose dolphins, rough-toothed dolphins, and short-finned pilot whales off Kaua‘i indicate that core ranges (i.e., the 50 percent kernel density polygons) for all three species overlap with PMRF. Continued collection of movement and habitat use data from all species should allow for a better understanding of the use of the range as well as provide datasets that can be used to estimate received sound levels at animal locations and examine potential responses to exposure.
Citation:
Baird, R.W., A.N. Dilley, D.L. Webster, R. Morrissey, B.K. Rone, S.M. Jarvis, S.D. Mahaffy, A.M. Gorgone, and D.J. Moretti. 2015. Odontocete Studies on the Pacific Missile Range Facility in February 2014: Satellite-Tagging, Photo-Identification, and Passive Acoustic Monitoring. Prepared for Commander, U.S. Pacific Fleet, submitted to Naval Facilities Engineering Command, Pacific by HDR Environmental, Operations and Construction, Inc.
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