NMML Harbor Porpoise Aerial Survey, Bristol Bay, Replicate 2, 1991Entry ID: seamap129
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 and was flown at an altitude of 152.2 m (500ft) and at an
airspeed of 100 kn. The second of three identical saw-tooth tracklines was
... flown along the south side of Bristol Bay. 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 = .35)
and 4.48 groups/100km^2 (SE=1.38).
Purpose: Although harbor porpoises, Phocoena phocoena, are known to occur
throughout Alaska waters (Fiscus et al. 1976; Leatherwood and Reeves 1978;
Lawry et al. 1982; Leatherwood et al. 1983), few estimates of abundance exist.
In 1991, the National Marine Mammal Laboratory initiated a 3-yr 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. 2) Establish a baseline for detecting changes in abundance through time,
for analysis of trends.
SUPPLEMENTAL INFORMATION: Note: This dataset and associated effort data was
updated on Sept 8, 2005. Those who downloaded them before that date should
renew them. 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.
CURRENTNESS REFERENCE: ground condition
SPATIAL REFERENCE INFORMATION -
Horizontal Datum Name: D_WGS_1984
Ellipsoid Name: WGS_1984
Semi-major Axis: 6378137.000000
Denominator of Flattening Ratio: 298.257224
Data Set Citation
Dataset Originator/Creator: National Marine Mammal Laboratory
Dataset Title: NMML Harbor Porpoise Aerial Survey, Bristol Bay, Replicate 2, 1991
Dataset Series Name: OBIS-SEAMAP
Dataset Release Date: 2004-08-09 16:43:46.977852-04
Dataset Release Place: http://seamap.env.duke.edu/
Dataset Publisher: OBIS-SEAMAP
Data Presentation Form: vector digital dataOnline Resource: http://nmml.afsc.noaa.gov/
This data set description is a member of a collection. The collection is described in
Start Date: 1991-08-05Stop Date: 1991-08-12
Latitude Resolution: 0.000167 Decimal degrees
Longitude Resolution: 0.000167 Decimal degrees
Horizontal Resolution Range: 1 meter - < 30 meters
Access Constraints ACCESS CONSTRAINTS: Open public unless otherwise noted.
DISTRIBUTION LIABILITY: Not to hold OBIS-SEAMAP liable for errors in the data.
While we have made every effort to ensure the quality of the database, we
cannot guarantee the accuracy of these datasets. Also please refer to Use
Use Constraints Not to use data contained in OBIS-SEAMAP in any publication, product, or
commercial application without prior written consent of the original data
provider. To cite both the data provider and OBIS-SEAMAP appropriately after
approval of use is obtained. Also please refer to Distribution Liability.
Data Set Progress
Distribution Format: Shapefile
Role: TECHNICAL CONTACT
Role: DIF AUTHOR
Email: efujioka at duke.edu
LSRC A321 Box 90328
Province or State: NC
Postal Code: 27708
Role: TECHNICAL CONTACT
Email: Janice.Waite at noaa.gov
NATIONAL MARINE MAMMAL LABORATORY 7600 Sand Point Way N.E.
Province or State: Washington
Postal Code: 98115-6349
M. Dahlheim et al. Harbor porpoise (Phocoena phocoena) abundance in Alaska:
Bristol Bay to Southeast Alaska, 1991-1993. 2000. Marine Mammal Science. 16(1):
Creation and Review Dates
DIF Creation Date: 2007-01-22
Last DIF Revision Date: 2008-08-29