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In summer 1992, the south side of the Alaskan Peninsula and the Kodiak Archipelago 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. more

Purpose: 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-yr 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. Supplemental information: 9/8/2005: This dataset and associated effort data were updated. Those who downloaded them before that date should renew them. The ability of the observers to sight porpoise was sensitive to environmental conditions. As expected, when conditions deteriorated the number of porpoises observed declined.

Biology > Mammals
Marine, Brackish water, Terrestrial, INE, USA, Alaska, Cetacea

Geographical coverage
INE, USA, Alaska

Temporal coverage
11 June 1992 - 23 June 1992

Taxonomic coverage
Cetacea [WoRMS]

Occurrence of biota

Duke University; Nicholas School of the Environment and Earth Sciences; Marine Laboratory, more National Oceanic and Atmospheric Administration; National Marine Mammal Laboratory, moredata creator

Related datasets
Published in:
OBIS-SEAMAP: Spatial Ecological Analysis of Megavertebrate Populations, more

Dataset status: Completed
Data type: Data
Data origin: Research: field survey
Metadatarecord created: 2015-06-22
Information last updated: 2015-06-22
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