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Ziphius cavirostris presence relative to vertical and temporal variability of oceanographic conditions in the southern california bight

Cite this dataset

Schoenbeck, Clara et al. (2024). Ziphius cavirostris presence relative to vertical and temporal variability of oceanographic conditions in the southern california bight [Dataset]. Dryad. https://doi.org/10.5061/dryad.8gtht76w1

Abstract

The oceanographic conditions of the Southern California Bight (SCB) dictate the distribution and abundance of prey resources and therefore the presence of mobile predators, such as goose-beaked whales (Ziphius cavirostris). Goose-beaked whales are deep-diving odontocetes that spend a majority of their time foraging at depth. Due to their cryptic behavior, little is known about how they respond to seasonal and interannual changes in their environment. This study utilizes passive acoustic data recorded from two sites within the SCB to explore the oceanographic conditions that goose-beaked whales appear to favor. Utilizing optimum multiparameter analysis, modeled temperature and salinity data are used to identify and quantify these source waters: Pacific Subarctic Upper Water (PSUW), Pacific Equatorial Water (PEW), and Eastern North Pacific Central Water (ENPCW). The interannual and seasonal variability in goose-beaked whale presence was related to the variability in El Niño Southern Oscillation events and the fraction and vertical distribution of the three source waters. Goose-beaked whale acoustic presence was highest during the winter and spring and decreased during the late summer and early fall. These seasonal increases occurred at times of increased fractions of PEW in the California Undercurrent and decreased fractions of ENPCW in surface waters. Interannual increases in goose-beaked whale presence occurred during El Niño events. These results establish a baseline understanding of the oceanographic characteristics that correlate with goose-beaked whale presence in the SCB. Furthering our knowledge of this elusive species is key to understanding how anthropogenic activities impact goose-beaked whales.

README: Ziphius cavirostris presence relative to vertical and temporal variability of oceanographic conditions in the southern california bight

https://doi.org/10.5061/dryad.8gtht76w1

Dates of Collection: July 2007-September 2020 (H), January 2009-September 2020 (N)

Geographic Location of Data Collection:

Site Latitude Longitude Depth (m)
H 32° 50.76’N  119° 10.57’ W 1000
N 32° 22.21’ N 118° 33.85’ W 1300

Description of the data and file structure

File List:

  1. SiteH_Zc_monthly_bin.csv
  2. SiteN_Zc_monthly_bin.csv

This study used passive acoustic monitoring to study goose-beaked whale presence at two sites within the Southern California Bight; sites H and N. Each site has a separate csv file that includes the monthly bins, minutes of presence without percent effort accounted for, the percent effort, and the minutes of presence adjusted for percent effort. The first column, “bin”, indicates the month and year of the monthly bins. Goose-beaked whale presence, not accounting for percent effort, is given in minutes per month, indicated by “Zc_pres”. Percent effort can be found in the column “perc_eff”. Total monthly minutes of goose-beaked whale presence, adjusted for percent effort, is in the final column, “Zc_pres_eff_adj”. Times of “NaN” presence indicate periods of no effort.

Methods

Acoustic data was collected using High-frequency Acoustic Recording Packages (HARPs, Wiggins and Hildebrand, 2007), passively recorded the ocean soundscape with a 200 kHz sampling frequency and 16-bit quantization, resulting in an effective bandwidth of 10 Hz to 100 kHz. Each HARP hydrophone was calibrated in the laboratory before initial deployment, while representative full systems were also calibrated at the US Navy’s Transducer Evaluation Center facility to verify the laboratory calibrations. Consistent deployments provided a near-continuous time series at both acoustic monitoring sites. Any gaps in the time series were due to battery life, data storage capacity, system failure, and/or vessel and crew availability to service the instruments.

Goose-beaked whale echolocation signals were identified using a combination of automated detection and manual verification techniques (Baumann-Pickering et al., 2014). All echolocation clicks were first identified using the automated Teager Kaiser energy detector (Soldevilla et al., 2008: Roch et al., 2011). Individual click detections were then filtered with a 10-pole Butterworth band-pass filter with a passband between 5 kHz and 95 kHz. The absence or presence of beaked whale FM echolocation pulses was determined based on 75 second segments with a minimum requirement of seven detections. These segments were then classified as containing beaked whale presence if more than 13% of all initially detected signals had peak and center frequencies above 32 and 25 kHz, a duration longer than 355 μs, and an upsweep rate of more than 23 kHz/ms (Baumann-Pickering et al., 2013).

The automatically detected beaked whale clicks were then verified using DetEdit, an open-source software for visualizing events within large acoustic datasets (Solsona-Berga et al., 2020). Once clicks were verified by a trained analyst, the number of FM pulse positive minutes was summed for each day and month. Goose-beaked whale presence data was determined as the number of FM pulse positive minutes recorded. Total monthly minutes of goose-beaked whale presence were used to examine the seasonal and interannual patterns in presence. Finally, to account for variations in recording efforts over time at each site, minutes of presence were divided by percent effort for each month.

References:

Baumann-Pickering, S., McDonald, M. A., Simonis, A. E., Solsona Berga, A., Merkens, K. P. B., Oleson, E. M., Roch, M. A., Wiggins, S. M., Rankin, S., Yack, T. M., & Hildebrand, J. A. (2013). Species-specific beaked whale echolocation signals. Journal of the Acoustical Society of America, 134, 2293-2301. https://doi.org/10.1121/1.4817832

Baumann-Pickering, S., Roch, M. A., Brownell Jr, R. L., Simonis, A. E., McDonald, M. A., Solsona-Berga, A., Oleson, E. M., Wiggins, S. M., & Hildebrand, J. A. (2014). Spatio-temporal patterns of beaked whale echolocation signals in the North Pacific. PLoS ONE, 9(1). https://doi.org/10.1371/journal.pone.0086072

Roch, M. A., Klinck, H., Baumann-Pickering, S., Mellinger, D. K., Qui, S., Soldevilla, M. S., & Hildebrand, J. A. (2011). Classification of echolocation clicks from Odontocetes in the Southern California bight. The Journal of the Acoustical Society of America, 129(1), 467–475. https://doi.org/10.1121/1.3514383 

Soldevilla, M. S., Henderson, E. E., Campbell, G. S., Wiggins, S. M., Hildebrand, J. A., & Roch, M. A. (2008). Classification of risso’s and Pacific white-sided dolphins using spectral properties of echolocation clicks. The Journal of the Acoustical Society of America, 124(1), 609–624. https://doi.org/10.1121/1.2932059 

Solsona-Berga, A., Frasier, K. E., Baumann-Pickering, S., Wiggins, S. M., & Hildebrand, J. A. (2020). DetEdit: A graphical user interface for annotating and editing events detected in long-term acoustic monitoring data. PLOS Computational Biology, 16(1). https://doi.org/10.1371/journal.pcbi.1007598

Wiggins, S. M., & Hildebrand, J. A. (2007). High-frequency acoustic recording package (harp) for broad-band, long-term Marine Mammal Monitoring. 2007 Symposium on Underwater Technology and Workshop on Scientific Use of Submarine Cables and Related Technologies. https://doi.org/10.1109/ut.2007.370760 

Funding

Office of Naval Research, Marine Mammal and Biology Program

U.S. Navy Pacific Fleet