Beaked whale foraging pulses were detected on the Pacific Missile Range Facility (PMRF) off Kauaʻi, Hawaiʻi, via long term passive acoustic monitoring. The unidentified pulses do not match foraging pulses of known species on the range but are similar to the unidentified beaked whale first detected at Cross Seamount, Hawaiʻi. Although there has not been a visual confirmation of the unidentified beaked
Automated passive acoustic detection, classification, and localization (DCL) methods are employed to deal with large volumes of acoustic data to support estimating the sound pressure levels (SPLs) that marine mammals are exposed to from mid-frequency active sonar (MFAS) during US Naval training events. These methods are applied to a training event involving MFAS conducted February 2012 in Hawaiian waters with thirty one hydrophones of data collected continuously over an 11 day period. The automated methods detect and determine locations of marine mammals, specifically minke and beaked whales, and the times of the MFAS transmissions utilizing custom C + + algorithms. Streamlined manual validation methods are employed which utilize custom Matlab display routines. Animal locations uncertainties are addressed for the two different species. Once the transmitting ship and animal locations are determined acoustic propagation modeling is utilized to estimate the sound pressure levels (in dB re 1 micro Pascal) that an animal, or group of animals, were exposed to. Surface ducted propagation conditions can result in species such as beaked whales being exposed to over 30 dB higher SPL’s when they return to the surface to breathe compared to when at depth foraging.
Beaked whale foraging dive clicks similar to those detected at Cross Seamount were detected during passive acoustic monitoring of marine mammals at the Pacific Missile Range Facility (PMRF) off Kauai, Hawaii using bottom-mounted hydrophones from January 2007 through August 2018. The Cross Seamount beaked whale (BWC) foraging dive click frequency sweeps from approximately 18 kHz to above the recording bandwidth of the PMRF sensors of 48 kHz at inter-click-intervals of 0.14 s (std 0.06 s). These unique clicks have only been detected at Cross Seamount and around the Hawaiian Islands, and because they have only been detected at night there has been no visual detections or species confirmation. However, they are distinctive enough to automatically detect, and can be used to describe basic presence at PMRF. Detections averaged 0.047 dives/h (in a 24-h cycle), and occurred almost entirely on the southern part of the range (water depth <1000 m). 702 BWC foraging dives were used to determine a foraging dive baseline over a 12-year period, to compare foraging dive rates during US Naval exercise events and baseline periods, and to contrast BWC foraging dive behavior from Blainville’s beaked whale foraging dive behavior at PMRF.
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