Gray whale visual sightings from shore 2014-2015

Regina A. Guazzo, Scripps Institution of Oceanography

Dataset credit

National Oceanic and Atmospheric Administration, Southwest Fisheries Science Center


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



During the eastern North Pacific gray whale 2014–2015 southbound migration, acoustic call recordings, infrared blow detections, and visual sightings were combined to estimate cue rates, needed to convert detections into abundance. The gray whale M3 acoustic call rate was 2.3–24 calls/whale/day with an average of 7.5 calls/whale/day over the entire migration (southbound and northbound) and showed a positive trend from 30 December–13 February. The infrared camera blow rate averaged 49 blows/whale/hour over 5–8 January. With a call rate model, we estimated that 4,340 gray whales migrated south before visual observations began on 30 December, which is 2,829 more gray whales than used in the visual abundance estimate. This finding highlights the usefulness of cue rates to increase precision in abundance estimates. We suggest that visual observers increase their survey effort to all of December to verify gray whale abundance corrections. Probability of detection of a whale blow by the infrared camera was the same at night as during the day. However, probability of detection decreased beyond 2.1 km offshore, whereas visual sightings revealed consistent whale densities up to 3 km offshore. We suggest that future infrared camera surveys use multiple cameras optimized for different ranges offshore.



Supplemental information

Visual Observation Location: 36 26' 23.61" N 121 55' 20.5" W

The sheet labeled "Effort" contains start and end times for observations in both UTC and PST time zones. B indicates the observations were beginning and E indicates the observations were ending. times are in Matlab's datenum format: Days since January 0, 0000

The sheet labeled "Modeled Abundance" contains the estimated number of whales that passed each day. Date is the Julian Date in Matlab's datenum format: Days since January 0, 0000. The estimated number of whales each day are given as a probability distribution. Median and the 95% highest posterior density interval are reported. Methods are described by Durban et al. 2015.

The original datasheet is included in the downloadable zipped file.


Guazzo, R. A., Weller, D. W., Europe, H. M., Durban, J. W., D'Spain, G. L., and Hildebrand, J. A. in review. Migrating eastern North Pacific gray whale cue rates estimated from acoustic recordings, infrared images, and visual sightings. Scientific Reports.
Durban, J. W. and Weller, D. W. and Lang, A. R. and Perryman, W. L. 2015. Estimating gray whale abundance from shore-based counts using a multilevel Bayesian model. Journal of Cetacean Research and Management. 15/61-68.



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.
Only minimum required attributes are visible and downloadable online. Other attributes may be obtained upon provider's permission.

Attributes in dataset

Attribute (table column)Description
oidUnique ID number (generated by OBIS-SEAMAP)
speciesSpecies name recorded
sp_tsnTaxonomic Serial Number added by OBIS-SEAMAP
utc_timeJulian Time in Matlab datenum format, UTC time zone
local_timeJulian Time in Matlab datenum format, PST time zone
datetime_utcDate and time in UTC converted from utc_time
datetimeDate and time in local time zone converted from local_time
latitudeLatitude in decimal degrees
longitudeLongitude in decimal degrees
azimuthAzimuth to whale
rangeRange offshore in km
group_numberGroup identification number, each day starts again at 1
group_sizeEstimated number of whales in group
beaufortBeaufort sea state conditions
visibilityVisibility Conditions
directionDirection that the whales are traveling in
geomGeometry field added by OBIS-SEAMAP
Marine mammals3,958
Sea turtles0
Rays and sharks0
Other species0
Non spatial0
Non species0
Date, Begin2014-12-30
Date, End2015-02-13
Temporal prec.111111
Latitude36.41 - 36.46
Longitude-122.02 - -121.92
Coord. prec.6 decimal digits
Data typeAnimal sighting
Traveled (km)0
Contr. through
Sharing policy CC-BY-NC (Minimum)
Shared with OBIS
GBIF (via DOI)
See metadata in static HTML
See metadata in FGDC XML
See download history / statistics