Most exciting, however, was the strong correlation we found between acoustic detections and visual sightings. The basic fact that we heard more whales while also seeing more whales shows great promise that visual surveys may enable us to calibrate acoustic datasets in order to monitor whale population trends using acoustics alone. This is an important and encouraging first step in the long process of refining our analyses and statistical models. VISUAL OBSERVATIONS The study area is surveyed from the shore-based Fin Island Research Station located at the south-western corner of Fin Island (N53° 14.214”, W129° 22.325”). The station is still under construction and since we are completely off the grid, with no store within a 160-kilometre (100-mile) boat ride, whenever we were travelling by boat from one hydrophone station to another we would stop at a beach to look for driftwood that we could use to build a new viewing deck. We also hired a barge to bring in the remaining material we needed to complete the deck. During the 2018 season between one and three observers lived at the station full-time and recorded observations from sunrise to sunset. Several methods were used for observation: scanning visually at regular intervals; following marine mammals opportunistically; tracking ships; and monitoring mammals informally using photo identification when possible. Formal visual scans were conducted hourly from 06h00 to 21h00 Pacific Standard Time (PST). Each scan was conducted for 20 minutes, during which time the position, group size and behaviour of all detected marine mammals were recorded, as well as the presence of vessels. Observers conducted scans with tripod-mounted 25x Big Eyes. Observations were made from Fin Island between 10 May and 10 October. In this period we conducted 1,279 systematic 20-minute scans of the study area (436.1 hours), during which we logged 3,474 sightings of marine mammals and 2,089 sightings of vessel traffic. The sightings of marine mammals enabled us to map their location and characterise their group size and behaviour (see figure 10).
Photo by Jenn Dickie
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