NMML Harbor Porpoise Vessel Survey, SE Alaska, Fall 1991

Kimberly Goetz; Janice Waite

doi:10.15468/8b8pzg

NMML Harbor Porpoise Vessel Survey, SE Alaska, Fall 1991

Citation

Dahlheim, M. E., P. A. White, J. M. Waite. 2009. Cetaceans of Southeast Alaska: distribution and seasonal occurrence. Journal of Biogeography. 36: 410-426. https://doi.org/10.15468/8b8pzg accessed via GBIF.org on 2024-11-03.

Description

Original provider: National Marine Mammal Laboratory Dataset credits: National Marine Mammal Laboratory 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. Supplemental information: This dataset and associated effort data were updated on September 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. The ability of the observers to sight porpoise was sensitive to environmental conditions. As expected, when conditions deteriorated the number of porpoises observed declined.

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).

Phocoenoides dalli
common name: Dall's Porpoise rank: species
Phocoena phocoena
common name: Harbor Porpoise rank: species
Phoca vitulina
common name: Harbor Seal rank: species
Megaptera novaeangliae
common name: Humpback Whale rank: species
Orcinus orca
common name: Killer Whale rank: species
Cetacea
common name: cetaceans rank: order
Cetacea
common name: cetaceans rank: order
Cetacea
common name: cetaceans rank: order

Geographic Coverages

Alaska,Bristol Bay,Cook Inlet,Southeast Alaksa

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