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NMML Harbor Porpoise Vessel Survey, SE Alaska, Fall 1991
Dahlheim, M. E., P. A. White, J. M. Waite. 2009. Cetaceans of Southeast Alaska: distribution and seasonal occurrence. Journal of Biogeography. 36: 410-426
Availability: This dataset is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Data from an aerial survey in Southeast Alaska, Cook Inlet, and Bristol Bay conducted to study the Alaska harbor porpoise (Phocoena phocoena) in fall 1991. more
Abstract In fall 1991, Southeast Alaska, Cook Inlet, and Bristol Bay, 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. 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 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.
Biology > Mammals
Marine, I, North Pacific, Mammalia
I, North Pacific [Marine Regions]
12 September 1991 - 17 September 1991
OBIS-SEAMAP: Spatial Ecological Analysis of Megavertebrate Populations, more
Dataset status: Completed
Data type: Data
Data origin: Research
Metadatarecord created: 2012-11-13
Information last updated: 2012-11-14