Odontocete Studies Off the Pacific Missile Range Facility in February 2013: Satellite-Tagging, Photo-Identification, and Passive Acoustic Monitoring for Species Verification

摘要

A joint project in February 2013 off the Pacific Missile Range Facility (PMRF) combined passive acoustic monitoring and boat-based field efforts. There were 1,010 kilometers (km) (55.9 hours hr) of small-vessel field effort over the course of the 8-day project. Of the 55.9 hr of survey effort, 64.2 percent of time was spent within the PMRF instrumented hydrophone range boundaries, and 14.8 percent of the effort was in depths greater than 1, 000 meters (m). A total of 50.4 hr of acoustic monitoring coincided with the small-vessel field effort. There were 20 sightings of four species of odontocetes, 14 of which were directed by acoustic detections from the Marine Mammal Monitoring on Navy Ranges (M3R) system. Bottlenose dolphins were encountered on 12 occasions, spinner dolphins on four occasions, rough-toothed dolphins on three occasions, and short-finned pilot whales on one occasion. Recordings on the M3R system for species verification were made for three of the four species (all but spinner dolphins). During the encounters 3,875 photos were taken for individual identification, seven biopsy samples were obtained for genetic studies, and six satellite tags were deployed on three species (three on bottlenose dolphins, one on a rough-toothed dolphin, and two on short- finned pilot whales). Data from the tagged species show that all appear to have island-associated populations with restricted ranges, and the ranges of all three populations substantially overlap with the PMRF range. Based on preliminary sound propagation analyses1 and the locations of animals tracked during this study, all of these populations are likely exposed to mid-frequency active (MFA) sonar on the PMRF range, but appear to use the overall area in different ways, thus the likelihood of exposure to different sound levels also probably varies by species.