The role of variable oceanographic and environmental conditions on acoustic tracking effectiveness




Bedard, Jeannette

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Examining fish behaviour through acoustic tracking is a technique being employed more and more. Typically, research using this method focuses on detections without fully considering the influence of both the physical and acoustic environment. Here we link the aquatic environment of Cumberland Sound with factors influencing the detection effectiveness of fish tracking equipment and found multi-path signal interference to be a major issue while seasonal variabilty had little impact. Cumberland Sound is a remote Arctic embayment, where three species of deep-water fish are currently tracked, that can be considered as two separate layers. Above the 300 m deep sill, the cold Baffin Island Current follows a geostrophic pattern, bending into the sound along the north shore, circulating before leaving along the south shore. The warm deep water is replenished from the recirculated arm of the West Greenland Current occasionally flowing over the sill and down to a stable depth. This influx of water prevents deep water hypoxia, allowing the deep-dwelling fish populations in the sound to thrive. To complement the work done in Cumberland Sound, a year-long study of the underwater soundscape of another Arctic coastal site, Cambridge Bay, Nunavut, was conducted over 2015. Unlike other Arctic locations considered to date, this site was louder when covered in ice with the loudest times occurring in April. Sounds of anthropogenic origin were found to dominate the soundscape with ten times more snowmobile traffic on ice than open water boat traffic.



Fish Tracking, Arctic Oceanography, Arctic underwater soundscape