NMML Harbor Porpoise Aerial Survey, Bristol Bay, Replicate 3, 1991

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 third of three identical saw tooth track lines 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).