Aerial imagery is the most effective method National Marine Fisheries Service (NMFS) uses to 9 assess abundance of Steller sea lions (Eumetopias jubatus). These images are traditionally captured from 10 occupied aircraft, but the long distances between airfields along the 1,900 km Aleutian Island chain, inclement 11 weather during the survey season, and dangerous winds at sites adjacent to cliffs severely limit flying 12 opportunities. Due to the pressing need for current trend information for a population in persistent decline we 13 turned to a small unoccupied aircraft system (UAS), an APH-22 hexacopter. Our primary objective was to 14 supplement traditional aerial surveys during the annual abundance survey. The second objective was to test 15 whether the resolution of images captured with the hexacopter were adequate for sighting permanently marked 16 individuals. From June-July 2014, NMFS biologists based on a research vessel assessed sites from Attu Island 17 to the Delarof Islands (n = 23), surveying sites from land (n = 12) and with the hexacopter (n = 11).
18Simultaneously, Traditional aerial surveys were conducted east of the Delarof Islands (n = 172). This combined 19 approach enabled us to conduct the most complete survey of adult, juvenile, and newborn Steller sea lions in the 20 Aleutian Islands since the 1970s. Images collected also allowed for us to identify alpha-numeric permanent 21 marks on individuals as small as juveniles. With this successful implementation of UAS, NMFS plans to use the 22 hexacopter to supplement future surveys.
Journal of Unmanned Vehicle Systems
47UAS for wildlife studies requires a field tool that is easy-to-use, electric-powered, hand-launched, easy to 48 transport, and operable by one or two people.
49The APH-22 was built for the high resolution imagery payload, ideal for the capture of high-resolution 50 images. This platform has the qualities that are required for our wildlife studies (i.e., easy-to-use, electric 51 powered, hand-launched, easy to transport, and operable by one or two people; Jones et al. 2006). Previous 52 testing with a multi-rotor and fixed wing UAS led to our selection of the APH-22 multi-rotor UAS (Aerial 53 Imaging Solutions, Old Lyme, CT), based on the repeated successes of the NMFS Southwest Fisheries Science 54 Center employing the hexacopter in Antarctica (Perryman et al. 2012; Goebel et al. 2015). The ability to fly 55 multi-rotor aircrafts in any direction and hover in one place allows for precise positioning over areas of interest 56 for an extended period of time and enables the pilot to control the UAS comfortably even while in close 57 proximity to cliffs adjacent to sea lion sites. A hexacopter has the advantage of more stability in flight and an58 increase in power by about 50% for a 15% increase in weight when compared to similar quadrocopters.59 Hexacopters also produce less noise than quadrocopter platforms (Perryman et al. 2012) and can be landed60 safely after the loss of one, or even two, engines.
61The manufacturer integrated ...