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NMML Harbor Porpoise Aerial Survey, Bristol Bay, Replicate 1, 1991
Citation
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

Access data
Availability: Creative Commons License This dataset is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Description
Data from an aerial survey throughout the coastal waters of Bristol Bay conducted to study the Alaska harbor porpoise (Phocoena phocoena) in August 1991. more

From 4 to 13 August 1991, as part of a larger study, Alaska harbor porpoise (Phocoena phocoena) abundance was investigated during an aerial survey throughout the coastal waters of Bristol Bay. A Twin Otter was used as the survey platform. The surveys were flown at an altitude of 152.2 m (500 ft) and at an airspeed of 185 km/h. A single zigzag trackline was flown along the north side of Bristol Bay, and the first of three identical sawtooth tracklines was flown along the south side. 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 for Bristol Bay was 1.17 (SE = 0.35) and 4.48 groups/100 km2 (SE = 1.38). 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. 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.

Scope
Themes:
Biology > Mammals
Keywords:
Marine, I, North Pacific, Cetacea

Geographical coverage
I, North Pacific [Marine Regions]

Temporal coverage
4 August 1991 - 13 August 1991

Taxonomic coverage
Cetacea [WoRMS]

Contributors
Duke University, more National Oceanic and Atmospheric Administration; National Marine Mammal Laboratory, moredata owner

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

Publication
Based on this dataset:
Dahlheim, M. et al. (2000). Harbor porpoise (Phocoena phocoena) abundance in Alaska: Bristol Bay to southeast Alaska, 1991-1993. Mar. Mamm. Sci. 16(1): 28-45. hdl.handle.net/10.1111/j.1748-7692.2000.tb00902.x, more

URLs

Dataset information:

Dataset status: Completed
Data type: Data
Data origin: Research
Metadatarecord created: 2012-11-14
Information last updated: 2012-11-14
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