NMML Harbor Porpoise Aerial Survey, Kodiak Island, Replicate 2, 1992
National Marine Mammal Laboratory

Dataset credit

National Marine Mammal Laboratory

Contacts

RoleNameOrganization 
Primary contact Kimberly Goetz Duke University
Primary contact Janice Waite National Marine Mammal Laboratory
Data entry Ei Fujioka Duke University

Citation

Abstract

On 6 July to 9 August 1992, as part of a larger study, Alaska harbor porpoise (Phocoena phocoena) abundance was investigated during an aerial survey off Kodiak Island. Employing a Twin Otter as the survey platform, the second of three identical sawtooth tracklines was flown 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 off Kodiak Island was 1.41 (SE = 0.13) and 1.85 groups/100 km2 (SE = 6.03).

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.

References

Attributes

Overview

Attributes described below represent those in the original dataset provided by the provider.
Only minimum required attributes are visible and downlodable online. Other attributes may be obtained upon provider's permission unless otherwise noted below.

Attributes in dataset provided

Attribute (table column)Description
dataset
lineno
dupl
line
lleg
date
event
time
dtime
beaufort
cloudcov
portvis
starvis
pglar
sglar
airspd
alt
latdeg
latmin
dlat
londeg
lonmin
dlong
pobs
recorder
sobs
pilot
linenum
begwpt
endwpt
herdsize
spcode
common
tsnSpecies ITIS TSN
scientific
group
angle
perpdis
observ
grpsiz
comments
excluded
oidUnique ID number (generated by SEAMAP)
OBIS-SEAMAP ID133
Seabirds0
Marine mammals77
Sea turtles0
Rays and sharks0
Other species0
Non spatial0
Non species0
Total77
Date, Begin1992-07-06
Date, End1992-07-31
Temporal prec.111111
Latitude55.42 - 58.74
Longitude-159.97 - -151.77
Coord. prec.5 decimal digits
PlatformPlane
Data typeAnimal sighting
EffortYES (ID: 162)
Traveled (km)1,738
Effort hours9
Registered2004-08-09
Updated2004-08-09
StatusPublished
Sharing policy CC-BY-NC (Minimum)
Also availalbe from iOBIS
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1