NMML Harbor Porpoise Aerial Survey, Cook Inlet, 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. https://doi.org/10.15468/q42tgf accessed via GBIF.org on 2024-12-15.Description
Original provider: National Marine Mammal Laboratory Dataset credits: National Marine Mammal Laboratory Abstract: On 1 and 2 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 Cook Inlet. A Twin Otter was used to fly a single sawtooth trackline across Cook Inlet 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 for Cook Inlet was 1.33 (SE = 0.33) and 0.54 groups/100 km2 (SE = 0.31). 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. Supplemental information: This dataset and associated effort data were updated on Sept 8, 2005. Those who downloaded them before that date should renew them.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.
Sampling Description
Study Extent
NASampling
NAMethod steps
- NA
Additional info
marine, harvested by iOBISTaxonomic Coverages
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Delphinapterus leucascommon name: Beluga rank: species
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Phocoena phocoenacommon name: Harbor Porpoise rank: species
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Megaptera novaeangliaecommon name: Humpback Whale rank: species
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Balaenoptera acutorostratacommon name: Minke Whale rank: species
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Cetaceacommon name: cetaceans rank: order
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Cetaceacommon name: cetaceans rank: order
Geographic Coverages
Bibliographic Citations
Contacts
Kimberly Goetzoriginator
position: Primary contact
Duke University
email: ktg4@duke.edu
Janice Waite
originator
position: Primary contact
National Marine Mammal Laboratory
email: Janice.Waite@noaa.gov
OBIS-SEAMAP
metadata author
Marine Geospatial Ecology Lab, Duke University
A328 LSRC building
Durham
27708
NC
US
email: seamap-contact@duke.edu
homepage: http://seamap.env.duke.edu
OBIS-SEAMAP
distributor
Marine Geospatial Ecology Lab, Duke University
A328 LSRC building
Durham
27708
NC
US
email: seamap-contact@duke.edu
homepage: http://seamap.env.duke.edu
Kimberly Goetz
owner
position: Primary contact
Duke University
email: ktg4@duke.edu
Janice Waite
owner
position: Primary contact
National Marine Mammal Laboratory
email: Janice.Waite@noaa.gov
Kimberly Goetz
administrative point of contact
position: Primary contact
Duke University
email: ktg4@duke.edu
Janice Waite
administrative point of contact
position: Primary contact
National Marine Mammal Laboratory
email: Janice.Waite@noaa.gov