NMML Harbor Porpoise Vessel, SE Alaska, Spring 1993
National Marine Mammal Laboratory

Dataset credit

National Marine Mammal Laboratory


Primary contact Kimberly Goetz Duke University
Primary contact Janice Waite National Marine Mammal Laboratory
Data entry Ei Fujioka Duke University



In spring 1993, the Alaskan panhandle and Prince William Sound were surveyed for harbor porpoise (Phocoena phocoena) from the NOAA John N. Cobb using line-transect methodology. The shipboard platform was 28.36 m (93 ft) in length with a bridge height of 4.27 m (14 ft). To obtain data on seasonal movements of porpoise, a limited number of transects were made in areas of known porpoise concentrations. When a sighting was made, the following variables were recorded: time, angle, number of reticles to the sighting, radar distance (nm) to the shoreline at the same angle of the sighting, the species, the count of the porpoise seen (best, high, and low), and the animal(s) direction of travel. Search effort was recoded by noting the time and location of the ship at the beginning and end of each transect.


Although harbor porpoises, Phocoena phocoena, are known to occur throughout Alaska waters, few estimates of abundance exist. In 1991, the National Marine Mammal Laboratory initiated a 3 year study on Alaska harbor porpoises. The objectives of this program were to:
1) Obtain minimum population estimates in coastal waters using line transect methodology with a coefficient of variation for density estimates of less than 30% for each survey area, and
2) Establish a baseline for detecting changes in abundance through time, for analysis of trends.
The ability of the observers to sight porpoise was sensitive to environmental conditions. As expected, when conditions deteriorated the number of porpoises observed declined.

Supplemental information

This dataset and associated effort data were updated on September 8, 2005. Those who downloaded them before that date should renew them.




Attributes described below represent those in the original dataset provided by the provider.
Only minimum required attributes are visible and downlodable online. Other attributes may be obtained upon provider's permission unless otherwise noted below.

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 in dataset provided

Attribute (table column)Description
Marine mammals670
Sea turtles0
Rays and sharks0
Other species0
Non spatial0
Non species0
Date, Begin1993-04-30
Date, End1993-05-13
Temporal prec.111111
Latitude55.45 - 59.05
Longitude-136.46 - -131.86
Coord. prec.5 decimal digits
Data typeAnimal sighting
EffortYES (ID: 177)
Traveled (km)1,504
Effort hours129
Sharing policy CC-BY-NC (Minimum)
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