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

Kimberly Goetz; Janice Waite

doi:10.15468/zfsm2q

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. https://doi.org/10.15468/zfsm2q accessed via GBIF.org on 2023-06-08.

Description

Original provider: National Marine Mammal Laboratory Dataset credits: National Marine Mammal Laboratory Abstract: 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. 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

NA

Sampling

NA

Method steps

NA

Additional info

marine, harvested by iOBIS

Taxonomic Coverages

Scientific names are based on the Integrated Taxonomic Information System (ITIS).

Delphinapterus leucas
common name: Beluga rank: species
Eschrichtius robustus
common name: Gray Whale rank: species
Phocoena phocoena
common name: Harbor Porpoise rank: species
Orcinus orca
common name: Killer Whale rank: species
Balaenoptera acutorostrata
common name: Minke Whale rank: species
Lagenorhynchus obliquidens
common name: Pacific White-sided Dolphin rank: species
Cetacea
common name: cetaceans rank: order

Geographic Coverages

Alaska,Bristol Bay

Bibliographic Citations

Contacts

Kimberly Goetz
originator
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