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NMML Harbor Porpoise Aerial Survey, SE Alaska, Replicate 3, 1993
Dahlheim, M., A. York, R. Towell, J. Waite, and J. Breiwick. 2000. Harbor porpoise (Phocoena phocoena) abundance in Alaska: Bristol Bay to southeast Alaska, 1991-1993. Marine Mammal Science. 16(1):28-45
Availability: This dataset is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Data from an aerial survey from Prince William Sound to Dixon Entrance conducted to study the Alaska harbor porpoise (Phocoena phocoena) in June 1993. more
On 1 to 26 June 1993, as part of a larger study, Alaska harbor porpoise (Phocoena phocoena) abundance was investigated during an aerial survey from Prince William Sound to Dixon Entrance. Employing a Twin Otter as the survey platform, the third of three identical sawtooth tracklines was flown at an altitude of 152.2 m (500 ft) and at an airspeed of 185 km/h. Line-transect methodology was used, and only those observations made during optimal conditions were analyzed. Density of harbor porpoises was calculated using line transect estimates based on perpendicular distances of sightings to the cruise track of the airplane. On average, porpoise group size and density from Prince William Sound to Dixon Entrance was 1.22 (SE = 0.04) and 4.02 groups/100 km2 (SE = 7.42). 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. During the present study, it was not fiscally possible to survey all areas of the state in any one year. Accordingly, we selected sections of the state to survey in consecutive years to maximize the likelihood of including all of the animals for a particular area surveyed while minimizing the likelihood of significant movement between areas among survey years.
Biology > Mammals
Marine, I, North Pacific, Cetacea
I, North Pacific [Marine Regions]
3 June 1993 - 23 June 1993
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