Performance of manned and unmanned aerial surveys to collect visual data and imagery for estimating arctic cetacean density and associated uncertainty

Abstract

Manned aerial surveys have been used successfully for decades to collect data to infer cetacean distribution, density (number of whales/km2), and abundance. Unmanned aircraft systems (UAS) have potential to augment or replace some manned aerial surveys for cetaceans. We conducted a three-way comparison among visual observations made by marine mammal observers aboard a Turbo Commander aircraft; imagery autonomously collected by a Nikon D810 camera system mounted to a belly port on the Turbo Commander; and imagery collected by a similar camera system on a remotely controlled ScanEagle® UAS operated by the US Navy. Bowhead whale density estimates derived from the marine mammal observer data were higher than those from the Turbo Commander imagery; comparisons to the UAS imagery depended on survey sector and analytical method. Beluga density estimates derived from either dataset collected aboard the Turbo Commander were higher than estimates derived from the UAS imagery. Uncertainties in density estimates derived from the marine mammal observer data were lower than estimates derived from either imagery dataset due to the small sample sizes in the imagery. The visual line-transect aerial survey conducted by marine mammal observers aboard the Turbo Commander was 68.5% of the cost of the photo strip-transect survey aboard the same aircraft and 9.4% of the cost of the UAS survey.

Comparing manned to unmanned aerial surveys for cetacean monitoring in the Arctic: methods and operational results

“…Analytical results of this project (Ferguson et al 2018) indicate that long-range UAS surveys provide reliable information on marine mammal density that is comparable to the information collected by manned aerial surveys. However, for long-range surveys for marine mammals, at this time, the use of UAS is promising, but considerably more expensive and logistically complicated than manned aerial surveys.…”

“…Unfortunately, due to the complications of coordinating manned and UAV flights, weather, and technical issues, the team did not have the opportunity to fly two UAVs simultaneously. Science results are found in Ferguson et al (2018).…”

“…The manned aerial surveys were conducted using a Turbo Commander 690A, a fixedwing twin-engine turboprop aircraft. Observers were experienced prior participants in surveys of arctic marine mammals, and collected visual line-transect data on marine mammals and relevant environmental conditions consistent with previous studies in the area (Clarke et al 2014;Ferguson et al 2018). A high-resolution camera system (see UAS payload details) mounted in a belly port of the Turbo Commander was pointed vertically downward, and collected images every 2 s. This approach is very similar to that used by Koski et al (2013) to compare human observers to images from cameras onboard the aircraft, with the exception that our study added the direct comparison with vertical images collected by the UAS.…”

“…This paper describes the materials, methods, and operational results. A comparison of the data resulting from the project is provided separately (Ferguson et al 2018).…”

Common and Antarctic Minke Whales: Conservation Status and Future Research Directions

“…Visual monitoring, from boats, ships or airplanes, is still one of the most common approaches to study marine mammal distribution and abundance (Barlow, 2015;Hammond et al, 2017). Despite recent advances in visual monitoring methods (Ferguson et al, 2018), these approaches always will be limited for monitoring animals that spend a large proportion of their lives under water (Borchers et al, 2013;Thomson et al, 2013). In addition, visual surveys are dependent on daylight, and good sighting and weather conditions, and are often spatially restricted to coastal areas.…”