NMML Small Cetacean Aerial Survey 1998

Original provider:
National Marine Mammal Laboratory

Dataset credits:
National Marine Mammal Laboratory

Abstract:
Researchers from NMML's Cetacean Assessment and Ecology Program conducted the line transect aerial surveys for harbor porpoise and Dall's porpoise from 27 May to 28 July 1998 in the Gulf of Alaska (offshore waters from Cape Suckling to Unimak Pass), Prince William Sound, and Shelikof Strait. Surveys were conducted from a NOAA Corps DeHavilland Twin Otter, flown at an altitude of 152.5 m (500 ft) and an airspeed of 185 km/hr (100 knots). Sawtooth lines were designed to cover the offshore waters from Cape Suckling to Unimak Pass (offshore of Kodiak Island) and included lines extending 15 nmi seaward, or to the 50 fathom line, whichever was farthest from shore and lines extending to the 1,000 fathom line. In Shelikof Strait a series of zigzag lines were designed between the Alaska Peninsula and Kodiak Island. Larger inlets and bays were also included in the survey. The survey in Prince William Sound consisted of two lines: one covering the central waters and one along the coast with extensions into selected inlets. Two primary observers surveyed from a bubble window on the left and right sides of the plane. An independent observer was positioned in a belly window. This observer surveyed the trackline directly below the plane to record animals missed on the trackline by the primary observers.