(Color online) Location of HARPs in the North Pacific and Gulf of Mexico. AI = Aleutian Islands, SA = Saipan, WK = Wake Atoll, NWHI = Northwestern Hawaiian Islands, MHI = Main Hawaiian Islands, CS = Cross Seamount, PA = Palmyra Atoll, WA = Washington, PS = Point Sur, HS = Hoke Seamount, SC = Southern California, GC = Gulf of California, GM = Gulf of Mexico. 1000 m (thin) and 2000 m (bold) isobaths are shown.
(Color online) Example sequence of Cuvier's beaked whale acoustic encounter on 2/27/2009 at 22:39 in Southern California (33° 08.4 N 118° 52.8 W): (top) LTSA (5 s averages, 2000-points DFT, Hann window), (middle) example FM pulse in spectrogram (60-points DFT, 98% overlap, Hann window), and (bottom) waveform.
(Color online) Example of software signal discrimination tool used to label an acoustic encounter consisting of 1431 Cuvier's beaked whale (Zc) FM pulses. (top) Mean spectra of all automatically detected FM pulses of the example encounter denoted by black bold line. Mean spectra of templates for all other FM pulse types are denoted as thin dashed lines with the exception of Zc, which is shown as a thin solid black line to highlight thesimilarity with the example encounter. (middle) Histograms of peak frequency (left, pfr) and IPI (right) with median values for pfr, center frequency (cfr), duration (dur), and IPI. (bottom) Mean spectra of encounter (left, solid line) and mean noise before each FM pulse (left, dashed line), with median peak-to-peak received level in dB re 1 μPa (ppRL) over all FM pulses in the encounter. Concatenated spectrogram of all FM pulses sorted by peak frequency showing variability (right).
Examples of species-specific frequency modulated (FM) pulses of known (I–IV, VI, VIII, XI) and unknown origin (V, VII, IX, X, XII). Time series with normalized (top) amplitude and (bottom) spectrogram (60-points DFT, Hann window, 98% overlap). bw = beaked whale.
Description of echolocations signals in all acoustic encounters per FM signal type of known (I–IV, VI, VIII, XI) and unknown origin (V, VII, IX, X, XII). Peak frequency has determined the order in which they are displayed. (top) Mean spectra (solid line) and mean noise preceding each signal (dashed line), (middle) concatenated spectrograms of all signals sorted by increasing peak frequency, and (bottom) histograms of inter-pulse interval (512-points DFT, Hann window, no overlap). bw = beaked whale. IPI = inter-pulse interval. n = number of signals. μ[1/2] = median IPI.
(Color online) Comparative box plot showing parameter variability of peak and center frequency, −10 dB bandwidth, and inter-pulse interval forall FM pulse types. Baird's (Bb),Longman's (Ip), Blainville's (Md), Cuvier's (Zc), Gervais' (Me), Deraniyagala's (Mh), Stejneger's beaked whale (Ms), and unknown signal types BW40, BW43, BW70, BWG and BWC.
Relationship of median center frequency (cf) and maximum body length (bl) of all beaked whale species with known signal type: Baird's (Bb), Longman's (Ip), Blainville's (Md), Cuvier's (Zc), Gervais' (Me), Deraniyagala's (Mh), Stejneger's beaked whale (Ms), and Northern bottlenose whale (Ha). Line of best fit (gray; cf = −3.9bl + 62.8, R 2 = 0.6; Pearson's linear correlation ρ = −0.8, p = 0.03).
Overview of HARP and array data (*) used for signal description. Regions indicate where data were collected, number in parentheses indicates ifmultiple sites in that geographic area had acoustic encounters. N = number of acoustic encounters; n = number of signals; AI = Aleutian Islands, SA = Saipan, NWHI = Northwestern Hawaiian Islands, MHI = Main Hawaiian Islands, CS = Cross Seamount, PA = Palmyra Atoll, WA = Washington, PS = Point Sur, HS = Hoke Seamount, SC = Southern California, GC = Gulf of California, GM = Gulf of Mexico.
Overview of signal parameters peak and center frequency, −10 dB bandwidth, duration, and inter-pulse interval (IPI) for all species given as median with 10th and 90th percentile in parentheses. For comparison, mean and standard deviation literature values of Northern bottlenose whale FM pulses were included ( Wahlberg et al., 2011 ). Column “Click” indicates whether an additional signal type similar to dolphin clicks has been observed during regular echolocation trains.
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