NMML Harbor Porpoise Aerial Survey, Alaska Peninsula, Replicate 2, 1992

Original provider:
National Marine Mammal Laboratory

Dataset credits:
National Marine Mammal Laboratory

Abstract:
On 6 July to 9 August 1992, as part of a larger study, Alaska harbor porpoise (<i>Phocoena phocoena</i>) abundance was investigated during an aerial survey off the south side of the Alaska Peninsula. Employing a Twin Otter as the survey platform, the second of two 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 the south side of the Alaska Peninsula was 1.1 (SE = 0.10) and 2.03 groups/100 km2 (SE = 1.65).