From 2011 through 2025, 25 LIMPET satellite tags were deployed on rough-toothed dolphins (Steno bredanensis) off the island of Kauaʻi, Hawaiʻi, part of a known island-associated resident community whose range overlaps with the Pacific Missile Range Facility (PMRF). Navy testing and training activity regularly occurs on PMRF and often includes the use of MFAS. Twelve of the tags recorded dive data; ten of the tags overlapped with periods of MFAS exposure from hull-mounted surface ships, active sonobuoys, and helicopter-dipping sonars; and five animals were present for all five phases of the training (Before, Phase A [training activity but no MFAS], Interphase, Phase B [training activity with MFAS], and After). Median received levels for these animals were estimated to be 141 to 159.8 dB re 1µPa for hull-mounted MFAS (n=10); 84 to 123.5 dB re 1µPa for helicopter-dipping MFAS (n=6), and 77.2 to 103.5 dB re 1µPa for active sonobuoys MFAS (n=10). Tracks resulting from Argos satellite and GPS positions were smoothed and interpolated every 5-min using crawl; the subsequent step lengths between positions (in meters), speeds (in m/s), turning angles between positions (in radians), and heading between positions (in bearing degrees) were compared for all animals and for the five animals with data in all five phases using Kruskal-Wallis Analyses and Multiple Comparison tests.
Citation:
Henderson, E.E., R.W. Baird, C.R. Martin, M.A. Kratofil, A.E. Harnish, S.D. Mahaffy, and S.W. Martin. 2025. Behavioral Response of Rough-Toothed Dolphins to Exposures from Multiple Sources of Sonar. Poster presented at the Seventh International Conference on the Effects of Noise on Aquatic Life, June 29-July 4, 2025, Prague, Czech Republic.
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