Passive acoustic monitoring of cetaceans at intertidal weirs in Minas Basin, Nova Scotia
LE3 .A278 2014
Bachelor of Science
Environmental & Sustainability Studies
Tidal energy development sites, including the Fundy Ocean Research Centre for Energy (FORCE) in Minas Passage in the Bay of Fundy, present potential risks to marine mammals. Passive acoustic monitoring (PAM) systems provide a means to acoustically detect cetacean presence and activity. We used passive acoustic hydrophones to examine the click-trains of the Atlantic harbour porpoise (Phocoena phocoena), the most abundant cetacean species in the Minas Basin and Minas Passage. This project is part of a larger study examining the usefulness of intertidal weirs as monitoring platforms, and aims to better inform FORCE about fish and marine mammal movements in the region. The project involved cetacean monitoring from the intertidal zone near the FORCE test area, and at two intertidal weirs with the aid of two PAM technologies, the Porpoise Detector (C-POD; Chelonia Ltd.) and the icListenHF hydrophone (icListenHF; Ocean Sonics Ltd.). Seasonal abundances of commercial and non-commercial fishes were determined by their capture in weirs at low tide. Harbour porpoise were detected by both PAM technologies near to the Bramber weir site, but were rarely within the listening range (100-200 m) of the C-PODs located at the Five Islands weir site. Peaks in porpoise presence near the Bramber weir occurred during the spring and fall. Detections were uncommon during mid-June to August, mirroring known seasonal trends in Minas Passage, and suggesting that porpoise are located in cooler waters west of Minas Passage during the warm summer months. There was no apparent relationship between porpoise presence and prey abundance in weir catches, suggesting the use of C-POD hydrophones at intertidal weir sites is not an effective method of collecting information on porpoise movements relative to the distribution of their prey. The icListenHF outperformed the C-POD in detection range and thus listening volume, indicating the icListenHF is more appropriate for monitoring within an intertidal/subtidal environment than C-PODs.
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