DOI: 10.6076/d1vs3r
title: Examples of killer whale (Orcinus orca) calls from passive acoustic monitoring in the Gulf of Alaska

description: Three killer whale (Orcinus orca) ecotypes are found in the northeastern
 Pacific: residents, transients, and offshores. Each ecotype produces
 distinct, stereotypic pulsed calls that serve as acoustic indicators of
 presence. To investigate the spatial and temporal occurrence of each
 ecotype in the Gulf of Alaska, long-term acoustic recorders were
 intermittently deployed from 2011 to 2019 at seven sites along the
 continental shelf and slope, in an abyssal region, and near offshore
 seamounts. This dataset contains examples of killer whale calls from these
 recordings. The examples are grouped based on the results of ecotype
 discrimination using established catalogs of call repertoires for each
 ecotype.
description: Passive acoustic monitoring was
 conducted in the Navy’s Gulf of Alaska Temporary Maritime Activity Area
 (GATMAA) using High-frequency Acoustic Recording Packages (HARPs) from
 July 2011 to September 2019. HARPs were deployed in a seafloor
 mooring configuration with the hydrophones suspended at least 10 m above
 the seafloor, except for Abyssal where the seafloor was at 4,000 m and the
 hydrophone at 1,200 m. Each HARP hydrophone was calibrated in the
 laboratory to provide a quantitative analysis of the received sound field.
 Representative data loggers and hydrophones were also calibrated at the
 Navy’s Transducer Evaluation Center facility to verify the laboratory
 calibrations. The seven sites monitored spanned the
 continental shelf (sites Kenai Shelf and Kodiak Shelf), the continental
 slope (sites Kodiak Slope and Kenai Slope), deep, offshore water (site
 Abyssal), and offshore seamounts (sites Quinn and Pratt). Kenai Shelf was
 monitored intermittently from July 2011 to September 2014, Kodiak Shelf
 almost continuously from June 2013 to September 2014, Kodiak Slope from
 April to September 2019, Kenai Slope intermittently from July 2011 to
 September 2019, Abyssal from April to September 2017, Quinn intermittently
 from June 2013 to September 2017, and Pratt almost continuously from
 September 2012 to September 2014. Each HARP sampled continuously at
 200 kHz except for one deployment each at Kenai Shelf and Kenai Slope,
 where a duty cycle was used, and one deployment each at Kenai Shelf and
 Quinn, which were sampled at 320 kHz. Duty-cycled deployments recorded
 for 10 minutes on and 2 minutes off. There were 4,545 days of recording
 effort overall. Before analysis, data were decimated by a
 factor of 20 for more effective scanning up to 5 kHz (8 kHz for
 deployments that were sampled at 320 kHz). Long-term spectral averages
 (LTSAs) were created using a 5-s time average and a 10-Hz resolution and
 were scanned by an analyst for killer whale whistles and pulsed calls
 using <em>Triton</em>, custom MATLAB (MathWorks, Natick, MA)
 software. When a potential killer whale signal was identified in the LTSA,
 a 30-s long spectrogram (1000-point FFT length, 90% overlap) was examined
 to confirm that the calls belonged to killer whales. Calls were logged as
 encounters, where each encounter was bounded by at least 15 min of
 recording that did not contain any calls.  Each encounter was
 later examined for pulsed calls which, when found, were scrutinized in a
 30-s spectrogram window in order to visually and aurally identify call
 types that could be used to distinguish between different ecotypes. An
 encounter was only classified to ecotype level if calls from the encounter
 could be positively matched to existing call repertoires. Resident and
 transient call types were identified using a digitized call catalog made
 from recordings provided by H. Myers (North Gulf Oceanic Society,
 unpublished data). These call types were from previously published call
 catalogs and from vessel surveys with resident killer whales (North Gulf
 Oceanic Society, unpublished data). Resident and transient encounters were
 confirmed by H. Myers and D. Olsen. Offshore encounters were confirmed by
 J. Pilkington by matching calls to a digitized call catalog of offshore
 calls made from field recordings taken during encounters with
 photo-identified offshore killer whales (DFO Cetacean Research Program,
 unpublished data). Encounters that could not be identified to the ecotype
 level were labeled unknown. Unknown encounters were typically short in
 duration and contained short and faint calls that were not suitable for
 making ecotype identifications.
description: Please view the README.txt file for more information.