Gray whale Infrared blow detections from shore 2015

National Oceanic and Atmospheric Administration, Southwest Fisheries
Science Center

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.

N/A

Infrared camera located at 36 26' 24.61" N 121 55'19.41"W

"Effort" tab gives the start and end times of each infrared video in Julian Date,
Matlab datenum format: Days since Jan 0, 0000. Note that there are short
gaps between videos.

The original datasheet is included in the downloadable zipped file.

Overview

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
oid	Unique ID number (generated by OBIS-SEAMAP)
species	Species name recorded
sp_tsn	Taxonomic Serial Number added by OBIS-SEAMAP
utc_time	Julian Time in Matlab datenum format, UTC time zone
local_time	Julian Time in Matlab datenum format, PST time zone
datetime	Date and time in local time zone converted from local_time
datetime_utc	Date and time inUTC converted from utc_time
latitude	Latitude in decimal degrees
longitude	Longitude in decimal degrees
range	Range offshore in km
azimuth	Azimuth to whale blow
obs_count	definition not provided
geom	Geometry field added by OBIS-SEAMAP