Assessing Exposure and Response of Tagged Blainville’s on PMRF

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Tagging of cetaceans on or near active U.S. Navy training ranges provides for opportunistic behavioral response studies as the animals are exposed to real-world Navy training and testing activity, as compared to short duration-controlled exposure studies. Four Blainville’s beaked whales were satellite-tagged on the Pacific Missile Range Facility (PMRF) off the island of Kaua‘i in the Hawaiian Islands in 2014, 2021, and 2022. The animal tagged in 2014 left the area immediately, but their tag data still provides useful baseline information of behavior and habitat use in the area. Two Blainville’s beaked whales were tagged from the same group in 2021. They remained together and were highly synchronized in their dive and movement behavior until the onset of mid-frequency active sonar (MFAS), at which time the whales appeared to separate. The dive behavior of the two animals tagged in 2021 were compared to acoustically detected group vocal periods (GVPs) on the range; 23 deep foraging dives were matched to GVPs, including three during MFAS exposures from three sources: hull-mounted MFAS, active sonobuoys, and helicopter-dipping MFAS.