Marine mammal sightings by analysts of digital imagery versus aerial surveyors: a preliminary comparison

Sightings of marine mammals made by protected species observers (PSOs) on manned aircraft were compared to sightings obtained from later review of high-definition (HD) video and digital single lens reflex (DSLR) camera imagery covering the same swaths and collected concurrent with the PSO observations. If the data were comparable, future similar surveys could be conducted with unmanned aerial systems or manned aircraft without PSOs. Two reviews were conducted on the DSLR images: one used image enhancement and scanned the images at full resolution of the cameras (detailed review) and the other flashed images at one ninth resolution on monitors for three to four seconds using a slide show format to simulate the view a PSO would have out an airplane window. Image reviewers saw fewer animals in HD video than did PSOs but sample sizes were small. During detailed review of DSLR imagery, reviewers saw similar numbers of cetaceans and polar bears and slightly more pinnipeds as compared to PSOs. PSOs saw more animals than the quick review found, but changes to the quick review process are suggested that will increase detection rates. Additional data are required to confirm the results presented here and to determine whether photographic versus PSO detections are similar across varying survey conditions.