A description of echolocation clicks recorded in the presence of True's beaked whale (Mesoplodon mirus)

摘要: True's beaked whales (Mesoplodon mirus) were encountered on two separate shipboard surveys 24 July 2016 and 16 September 2017 in the western North Atlantic Ocean. Recordings made using a hydrophone array towed 300 m behind ship. In 2016, three different groups sighted within 1500 m of ship; clicks recorded for 26 min. 2017, single group five was tracked over course hours which ship maintained distance <4000 m from group. A total 2938 frequency-modulated (FM) 7 buzzes both encounters. Plausible inter-click-intervals (ICIs) calculated 2763 clicks, frequency duration measurements 2150 good quality FM clicks. The median peak frequencies 43.1 kHz (2016, n = 718) 43.5 kHz (2017, n = 1432). Median ICIs 0.17 s (2016) 0.19 s (2017). spectra closely resemble Gervais's whale europaeus) distinguishing between species acoustic data sets proves difficult. behavior previously unknown; this study provides description echolocation produced by species.True's dist...