Gray whale localized acoustic detections in Granite Canyon 2014-2015

Regina A. Guazzo, Scripps Institution of Oceanography

Dataset credit

Scripps Institution of Oceanography, University of California San Diego


Primary contact Regina Guazzo Naval Information Warfare Center Pacific
Data entry Ei Fujioka Duke University



Eastern North Pacific gray whales make one of the longest annual
migrations of any mammal, traveling from their summer feeding areas in
the Bering and Chukchi Seas to their wintering areas in the lagoons of Baja
California, Mexico. Although a significant body of knowledge on gray whale
biology and behavior exists, little is known about their vocal behavior while
migrating. In this study, we used a sparse hydrophone array deployed
offshore of central California to investigate how gray whales behave and
use sound while migrating. We detected, localized, and tracked whales for
one full migration season, a first for gray whales. We verified and localized
10,644 gray whale M3 calls and grouped them into 280 tracks. Results
confirm that gray whales are acoustically active while migrating and their
swimming and acoustic behavior changes
on daily and seasonal time scales. The seasonal timing of the calls verifies
the gray whale migration timing determined using other methods such as
counts conducted by visual observers. The total number of calls and the
percentage of calls that were part of a track changed significantly over both
seasonal and daily time scales. An average calling rate of 5.7
calls/whale/day was observed, which is significantly greater than
previously reported migration calling rates. We measured a mean speed of
1.6 m/s and quantified heading, direction, and water depth where tracks
were located. Mean speed and water depth remained constant between
night and day, but these quantities had greater variation at night. Gray
whales produce M3 calls with a root mean square source level of 156.9 dB
re 1 µPa at 1 m. Quantities describing call characteristics were variable and
dependent on site-specific propagation characteristics.



Supplemental information

[2017-10-27] The data sheets in the zipped shapefile download file are

[2017-09-26] The number of localizations has increased by about 400 based
on a more correct method of counting calls.

Four moored hydrophone arrays were used to detect.
Hydrophone, Latitude, Longitude, Depth, Channel
NE 36.43778, -121.94417 52, 1
NW 36.43512, -121.96082 95, 2
SE 36.42679, -121.93743 43, 3
SW 36.41872, -121.94925 79, 4

The original data sheets provided by the provider are included in the
downloadable zip file. To get it, choose "Dataset on Dataset Page" and "As
shapefile" as desired options through the download processes on the
OBIS-SEAMAP Dataset Page.

The sheet labeled M3 contains attributes of each of the M3 calls that were
JulianTime: Matlab's datenum. Days since January 0, 0000
Latitude: Localized latitude of call
Longitude: Localized longitude of call
Tracked: 0 if not part of a track, 1 if call was part of track
WaterDepth: Depth in meters
RangeXX: Range to each of the hydrophones (NE,NW,SE,SW)
Duration_XX: Duration of call in seconds at each hydrophone
RL_rms_XX: Root Mean Square received level at each hydrophone (µPa)
RL_p2p_XX: Peak-to-Peak received level at each hydrophone (µPa)
SL_rms_XX: Root Mean Square source level at each hydrophone (dB re 1
SL_sel_XX: Sound Exposure Level source level at each hydrophone (dB re 1
SL_p2p_XX: Peak-to-Peak source level at each hydrophone (dB re 1 µPa)
PeakFreq_XX: Peak frequency at each hydrophone (Hz)
BW_3dB_XX: 3 dB Bandwidth around peak frequency at each hydrophone
MeanFreq_XX: Mean frequency at each hydrophone (Hz)
SigmaBW_XX: +/- sigma bandwidth at each hydrophone (Hz)

The sheet labeled M1 contains attributes of each of the M1 calls manually
detected on a single hydrophone (NE)
JulianTime: Matlab's datenum. Days since January 0, 0000
IPI: mean inter-pulse interval between pulses within a call
IPI_SD2: variance of inter-pulse intervals between pulses within a call
NumPulses: Total number of pulses within a call
PeakFreq_NE: Peak frequency at NE hydrophone (Hz)
BW3dB_NE: 3 dB Bandwidth around peak frequency at NE hydrophone (Hz)
MeanFreq_NE: Mean frequency at NE hydrophone (Hz)
SigmaBW_NE: +/- sigma bandwidth at NE hydrophone (Hz)

The sheet labeled M3 contains noise levels for every minute of recording
JulianTime: Matlab's datenum. Days since January 0, 0000
NoiseLevel_XX: Root median square noise level for the one minute period
starting at JulianTime (µPa) on the recordings from each hydrophone




This section explains attributes included in the original dataset. OBIS-SEAMAP restricts the attributes available to the public to date/time, lat/lon and species names/counts only. Should you need other attributes described here, you are encouraged to contact the data provider.

Attributes described below represent those in the original dataset provided by the provider.
All attributes are included in the downloadable file (CSV or ESRI File Geodatabase) for "Complete Set of Dataset".

Attributes in dataset

Attribute (table column)Description
oidUnique ID number (generated by OBIS-SEAMAP)
juliantimeJulian time, Matlab
obs_datetimeDate and time of the detection
latitudeLatitude in decimal degrees
longitudeLongitude in decimal degrees
speciesSpecies name recorded
sp_tsnTaxonomic Serial Number added by OBIS-SEAMAP
obs_countGroup size (blank; presence only)
pruned_ne1 if call was verified as a gray whale M3 on NE hydrophone, 0 otherwise
tracked1 if call was part of a track of verified gray whale calls, 0 otherwise
inarray_4hyds1 if a call was localized within the array and could be verified as a gray whale M3 call when looking at spectrograms from all four hydrophones, 0 otherwise
delaynwneTime difference of arrival (TDOA) in seconds between NW and NE hydrophones
delayseneTime difference of arrival (TDOA) in seconds between SE and NE hydrophones
delayswneTime difference of arrival (TDOA) in seconds between SW and NE hydrophones
samplestartDetection start time in samples since the start of the deployment
sampleendDetection end time in samples since the start of the deployment
samplemeanMean of samplestart and sampleend
lsqLeast-squared difference between the theoretical and measured TDOAs summed over the three TDOA measurements
geomGeometry field added by OBIS-SEAMAP
Marine mammals11,468
Sea turtles0
Rays and sharks0
Other species0
Non spatial0
Non species0
Date, Begin2014-12-01
Date, End2015-05-03
Temporal prec.111111
Latitude36.40 - 36.45
Longitude-121.98 - -121.92
Coord. prec.6 decimal digits
Data typeAcoustic - presence
EffortYES (ID: 1542)
Traveled (km)0
Travel hours19,718
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