Figure 1.
Overview of frequency-modulated (FM) upsweep pulses from known (I–IV, VII, IX) and unknown sources (V, VI, VIII, X,).
Each FM pulse type is shown with an example pulse time series (top) and spectrogram (middle, Hann-windowed 2 ms, 40-point DFT, 97% overlap), as well as a mean spectra (bottom, solid line) over all FM pulses from several acoustic encounters and mean noise (dotted line) extracted before each pulse. Inter-pulse interval (IPI) is specified in ms (value in time series plot).
Figure 2.
Locations of HARP recording sites (circles) across the North Pacific (top) and within the Southern California Bight (bottom).
Table 1.
HARP deployment details with recording start and end dates spanning multiple deployments, geographic locations and depths.
Table 2.
Relative distribution of daily presence of acoustic encounters for all FM pulse types by site, normalized for days of effort.
Figure 3.
Relative daily occurrence of FM pulse types by site (pie chart, see Table 2).
For each pie chart, the relative detection effort (number of days recorded) is displayed on the left, and the relative presence on the right. Site M in the Southern California Bight had the highest effort (relative effort of 1) and Kingman Reef had the highest percentage of days with acoustic encounters (relative presence of 1). A dark line through the relative effort is indicative of duty cycle and reflects the amount of continuous effort.
Table 3.
Percentage of number of days with detections per FM pulse type over all sites.
Figure 4.
Seasonality of Z. cavirostris (Zc, top panel) at sites SOCAL M, N and Hawai’i, of M. stejnegeri (Ms, middle panel) at sites Aleutian Islands Buldir, Gulf of Alaska CB, Washington Quinault Canyon, and SOCAL M, and of M. densirostris (Md, bottom panel) at sites Hawai’i and Kaua’i.
A point indicates partial monthly recording effort and data in that month was adjusted for reduced effort. Grey shaded areas show no monthly effort.
Figure 5.
Diel cycle of Cross beaked whale (BWC), M. densirostris (Md), Z. cavirostris (Zc), and M. hotaula (Mh) pooled over all sites and geographic regions (top panel), as well as for Md and Zc at select sites.
Dark shaded areas indicate nighttime. BWC displayed a clear nocturnal activity over all sites, Mh had a diel pattern with higher acoustic activity during the day, Zc had a slight diel pattern with higher activity from after midnight to mid-day over all sites, particularly pronounced at Pearl and Hermes Reef and SOCAL H. Md did not have a diel pattern, except at Hawai’i, where the pattern was similar to Zc.
Figure 6.
Distribution maps (light blue shaded area; adapted from [102]) of all known beaked whale species in the North Pacific (except Ip).
Acoustic encounter locations of title species (red circles) of known FM pulse types (Bb, Md, Zc, Ms, Mh) or potential FM pulse matches (Mg/BWC, Mpu/BW70, Mpe/BW43, Mc/BW40). Location of HARPs with no acoustic encounter of title species (black circles).
Table 4.
Presence (+) or absence (−) of beaked whales based on strandings (S), visual sightings (V), and acoustic FM pulse encounter (A). HI: Hawaiian Islands.