Flying beneath the clouds at the edge of the world: using a hexacopter to supplement abundance surveys of Steller sea lions ( Eumetopias jubatus) in Alaska

• Published in: Journal of Unmanned Vehicle Systems
• Main Authors: Sweeney, Kathryn L., Helker, Van T., Perryman, Wayne L., LeRoi, Donald J., Fritz, Lowell W., Gelatt, Tom S., Angliss, Robyn P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2016
• Subjects: Attu Island; Aleutian Island; Attu; Alaska; Aleutian Islands
• Online Access: http://dx.doi.org/10.1139/juvs-2015-0010; http://www.nrcresearchpress.com/doi/full-xml/10.1139/juvs-2015-0010; http://www.nrcresearchpress.com/doi/pdf/10.1139/juvs-2015-0010

Aerial imagery is the most effective method National Marine Fisheries Service (NMFS) uses to assess abundance of Steller sea lions (Eumetopias jubatus). These images are traditionally captured from occupied aircraft, but the long distances between airfields along the 1900 km Aleutian Island chain, inclement weather during the survey season, and dangerous winds at sites adjacent to cliffs severely limit flying opportunities. Because of the pressing need for current trend information for a population in persistent decline we turned to a small unoccupied aircraft system (UAS), an APH-22 hexacopter. Our primary objective was to supplement traditional aerial surveys during the annual abundance survey. The second objective was to test whether the resolution of images captured with the hexacopter was adequate for sighting permanently marked individuals. From June to July 2014, NMFS biologists based on a research vessel assessed sites from Attu Island to the Delarof Islands (n = 23), surveying sites from land (n = 12) and with the hexacopter (n = 11). Simultaneously, traditional aerial surveys were conducted east of the Delarof Islands (n = 172). This combined approach enabled us to conduct the most complete survey of adult, juvenile, and newborn Steller sea lions in the Aleutian Islands since the 1970s. Images collected also allowed for us to identify alpha-numeric permanent marks on individuals as small as juveniles. With this successful implementation of UAS, NMFS plans to use the hexacopter to supplement future surveys.