Odontocete Studies on the Pacific Missile Range Facility in February 2016: Satellite-Tagging, Photo Identification, and Passive Acoustic Monitoring
Baird, R.W., D.L. Webster, R. Morrissey, B.K. Rone, S.D. Mahaffy, A.M. Gorgone, D.B. Anderson and D.J. Moretti. 2017. Odontocete studies on the Pacific Missile Range Facility in February 2016: satellite-tagging, photo-identification, and passive acoustic monitoring. Prepared for Commander, Pacific Fleet, Environmental Readiness Division, Pearl Harbor, HI. Submitted to Naval Facilities Engineering Command (NAVFAC) Pacific, EV2 Environmental Planning, Pearl Harbor, HI under Contract No. N62470-15-D-8006 TO KB08 issued to HDR Inc., Honolulu, HI..
A joint project in February 2016 on and around the Pacific Missile Range Facility (PMRF) was carried out utilizing combined boat-based field efforts and passive acoustic monitoring from the Marine Mammal Monitoring on Navy Ranges (M3R) system. Five days of small boat effort were funded by the U.S. Navy and an additional two days of effort were funded by the National Marine Fisheries Service. There were 581 kilometers (36 hours [hr]) of small-vessel survey effort over the course of the seven‑day project. There were 20 sightings of four species of odontocetes, six of which were directed by M3R acoustic detections. Bottlenose dolphins (Tursiops truncatus) were encountered on five occasions, short-finned pilot whales (Globicephala macrorhynchus) on six, rough-toothed dolphins (Steno bredanensis) on eight, and pantropical spotted dolphins (Stenella attenuata) once. This was the first sighting of pantropical spotted dolphins on PMRF in CRC small-boat efforts off Kaua‘i or Ni‘ihau since 2003, and only the 10th sighting off Kaua‘i or Ni‘ihau. During the encounters 16,806 photos were taken for individual identification, and nine satellite tags were deployed on three species—six short-finned pilot whales (from four different social groups), two rough-toothed dolphins and one pantropical spotted dolphin. In addition, information from tag deployments on two short-finned pilot whales, one rough-toothed dolphin, and one bottlenose dolphin, tagged in September 2015 were included in analyses. All of the tagged rough-toothed dolphins and the bottlenose dolphin remained associated with the island of Kaua‘i and Ni‘ihau. Based on photo-identification all were part of groups known to be resident to the islands. Probability density analyses of all tag-location data obtained for bottlenose dolphins and rough-toothed dolphins tagged off Kauaʻi since 2011 indicate that core ranges (i.e., the 50 percent kernel density polygons) are relatively small (1,173 and 1,535 square kilometers [km2]). Tag data were available from five different social groups of short-finned pilot whales, one presumed to be from the pelagic population and four from the insular population. Probability density analyses were undertaken separately for 17 resident short-finned pilot whales tagged off Kaua‘i since 2008, and for six pilot whales tagged off Kaua‘i and O‘ahu thought to be from the pelagic population. Core range for the pelagic population was more than ten times larger (111,135 km2) than for the resident population (9,062 km2), and the overall range (using the 99 percent kernel density isopleth) was almost an order of magnitude larger for the pelagic population (695,419 km2). This suggests that the likelihood of exposure to mid-frequency active sonar on the PMRF varies substantially between the two populations. 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.