Introduction & Objectives

A shore-based platform, incorporating two high-powered 25 × 150-millimeter binoculars ("Big Eyes"), was evaluated as an alternative approach for surveying marine areas for protected species (marine mammals and sea turtles). 

Technical Approach

Systematic scans using Big Eyes were performed in Guam over 10 days in May 2013 and 10 days in March 2015 from a north-facing (193-m elevation) and a northeast-facing (143-m elevation) shore station, chosen for mostly unobstructed views of the ocean in areas that are difficult to access by small vessel due to strong winds and large waves. The horizon distance calculated from each elevation was 50 and 42 km, respectively. A SnapZoom1 digiscoping adapter, equipped with an iPhone or GoPro, was attached to the Big Eyes eyepiece allowing collection of photos and video, complementing super-telephoto (500- and 800-millimeter) photography on a Digital Single Lens Reflex camera to assist with species confirmation. 

Progress & Results

During a pilot study at a test site on Oahu (278meter [m] elevation), humpback whale (Megaptera novaeangliae) blows were visible through Big Eyes at 37 kilometers (km) away in Beaufort Sea State (BSS) 2. This suggests the approach could be effective at detecting baleen and sperm whales from long distances, priority species under the United States Department of the Navy's Marine Species Monitoring Program.

Despite a mean BSS of 5 or greater obscuring the visual arena for 90 percent of the survey time, observers recorded 32 odontocete and 38 turtle sightings. No baleen or sperm whales were observed. Odontocete sightings consisted of four confirmed species: spinner dolphins (Stenella longirostris; 66 percent, n=21), bottlenose dolphins (Tursiops truncatus; 6 percent, n=2), pilot whales (Globicephala macrorhynchus; 3 percent, n=1) and melon-headed whales (Peponocephala electra; 3 percent, n=1) and 7 unconfirmed (unidentified small dolphin; 16 percent, n=5, unidentified small whale; 3 percent, n=1, unidentified medium whale; 3 percent, n=1). The marine mammal sighting rate of 0.11 sightings per hour in March 2015 was less than four times the 0.47 sightings per hour during the May 2013 surveys, despite having one additional observer and a second pair of Big Eyes.