LE3 .A278 2020

2020

Redden, Anna
Sanderson, Brian

Acadia University

Master of Science

Masters

Biology

Biology

Atlantic harbour porpoise (Phocoena phocoena) are common to the inner Bay of Fundy, including the Minas Passage area where tidal energy development is underway. Towards determining the potential effects of tidal energy turbine installations in Minas Passage on harbour porpoise behaviour, this study used drifting passive acoustic monitoring (PAM) sensors to collect high-quality sound data, including porpoise echo location clicks. The study also applied new methods and procedures to process the hydrophone array datasets. A 2017 field study provided data for comparison of three monitoring methods: C-POD, icListenHF hydrophone with Coda click detector, and visual sightings. The broadband icListenHF hydrophone with Coda detected relatively more harbour porpoise vocalizations and was less susceptible to high flow noise. A follow up study in 2018 used an array of four synchronized hydrophones suspended from a drifter. Positional information was estimated from porpoise clicks. Click source level, effective sampling range (~30 m), and local porpoise abundance (~2.8 per km2) were estimated from detected clicks. Water masses west of Minas Passage appear to have greater porpoise vocalization activity, and likely greater porpoise abundance, than more eastern water masses. Echolocation click tracks suggest that porpoises sometimes exhibit little movement when at depth for extended periods. Video footage indicate near-surface swimming speeds of~2 m/s. On-beam click detections gave greater source level, a wider click envelope, and more reverberations at the tail of the click when compared to off-beam detections. This is consistent with anatomical focusing of sound to form a beam from many transmission paths within the porpoise. This study demonstrated that porpoise clicks can be used to reliably obtain porpoise position out to ~40 m, which is in line with turbine near-field monitoring needs.

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https://scholar.acadiau.ca/islandora/object/theses:3487