2015_WHB_19Aug_25mm_001124-001196.zip (English, French, JPG)

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2026-03-24

PURPOSE: An aerial survey of the Western Hudson Bay beluga whale (Delphinapterus leucas) population was conducted on August 19th, 2015 to provide a population estimate. Surveys were flown in a DeHavilland Twin Otter (DH-6) fitted with four bubble windows and an optical glass-covered camera hatch at the rear underbelly of the plane. A Global Positioning System (GPS) unit logged the position, altitude, speed, and heading of the aircraft each second. Surveys were initially flown at a target ground speed of 100 knots (185 km/h), and target altitudes of 1,000 ft (305 m) for visual surveys and 2,000 ft (610 m) for photographic surveys. After the second day of flying, the target ground speed was adjusted to 110 knots (204 km/h). Complete coverage of the two photographic strata was achieved using a Nikon D810 camera fitted with a 25 mm lens. The camera was mounted at the rear of the aircraft and directed straight down with the longest side perpendicular to the track line. The camera was connected to a GPS unit to geo-reference photographs, and to a laptop computer to control exposure settings and photo interval. At an altitude of 2,000 ft (610 m), the 25 mm lens captured a ground area of…

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