| Summary: | The impact of Remote Piloted Aircraft Systems (RPAS, or drones) on marine mammals remains poorly documented despite their increasing use by hobbyists and scientists. In the High-Arctic Archipelago of Svalbard, where marine mammals are facing increasing pressure from the coupled effects of climate modification and an expanding tourism industry, the use of RPAS remains largely unregulated to date. In this study we assessed the impacts of RPAS on marine mammals, conducting experimental flights to provide science-based management advice. Our novel approach included RPAS in a range of sizes and different approach strategies, and it accounted for RPAS sound levels as well as animal behaviour prior to and after RPAS flights. Harbour seals were more sensitive during pre-breeding, reacting at distances of 80 m, than during moulting. Walruses responded at distances of 50 m. Pre-experimental levels of alertness increased sensitivity to RPAS disturbance notably. Polar bears reacted to the sound of RPAS during take-off at 300 m, although response levels were relatively low and remained so even at 60 m. Belugas reacted only visually to RPAS, when flying ahead of the pod below 15 m. Our study highlights a range of factors that can influence sensitivity to RPAS including tidal state and swell, the presence of young individuals, ambient noise levels and RPAS approach strategy. Large variations in sound levels during overhead descents and other manual flights increase RPAS disturbance potential to a greater extent than RPAS size when flying pre-programmed profiles. Physiological state and levels of alertness prior to experimentation also affected RPAS disturbance potential. We provide empirically-derived flight distances that can help management authorities establish guidelines for the use of RPAS in Svalbard.
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