An evaluation of active acoustic methods for detection of marine mammals in the Canadian Beaufort Sea

Abstract

A commercially available fisheries sonar was mounted on an icebreaker and evaluated during an environmental baseline study in the Canadian Beaufort Sea, to determine the applicability of active acoustic monitoring (AAM) for marine mammal detection by comparing marine mammal observer (MMO) visual sightings and active acoustic detections. During 170 h of simultaneous MMO and AAM, 115 bowhead whales (Balaena mysticetus) and four beluga whales (Delphinapterus leucas) were visually sighted by MMOs, while 59 sonar detections of bowhead whales occurred using AAM. The fisheries sonar detected 92% of the cetaceans observed within 2,000 m. Additional observations of ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus) were recorded both by MMOs and AAM. Comparative results indicate that a commercially available active acoustic system can consistently detect marine mammals within varying ranges dictated by water column properties. Shallow environments and strong pycnoclines currently present challenges to AAM.

Summer distribution and habitat preference of beluga whale social groups in the Eastern Beaufort Sea

“…Although a strong increase in killer whale presence has been observed in the eastern Canadian Arctic (Ferguson et al 2010), no evidence indicates an increase in the predator presence in the western Canadian Arctic and the Beaufort Sea (Higdon and Ferguson 2009;Higdon et al 2013). Killer whales were not detected by recent acoustic surveys of marine mammals in the Canadian Beaufort Sea either (Pyć et al 2016). Belugas are present in polar bears' diet in the Beaufort Sea (Boucher et al 2019;Florko et al 2020), although in lower proportion than seals.…”

Automated detection and tracking of marine mammals: A novel sonar tool for monitoring effects of marine industry

“…However, accelerated development of active sonar systems for the subsea monitoring of potential security threats for the defence sector, and for fisheries research and management, provides a basis for tracking animal movements and monitoring avoidance or evasion behaviour of animals around tidal turbines (Hastie et al, 2014). Benoit-Bird & Au, 2003a;Doksaeter, Godo, Olsen, Nottestad, & Patel, 2009;Gonzalez-Socoloske & Olivera-Gomez, 2012;Nøttestad, Ferno, & Axelsen, 2002;Pyć, Geoffrey, & Knudsen, 2016) to track the movements of individual animals in a range of different habitats. Active sonar has been used extensively in studies of marine mammal behaviour underwater (e.g.…”

“…Active sonar has been used extensively in studies of marine mammal behaviour underwater (e.g. Benoit-Bird & Au, 2003a;Doksaeter, Godo, Olsen, Nottestad, & Patel, 2009;Gonzalez-Socoloske & Olivera-Gomez, 2012;Nøttestad, Ferno, & Axelsen, 2002;Pyć, Geoffrey, & Knudsen, 2016) to track the movements of individual animals in a range of different habitats. Hawaii.…”

“…Benoit-Bird & Au, 2003a;Benoit-Bird & Au, 2003b). To be effective as a long-term behavioural monitoring tool, a number of potential limitations need to be overcome (Pyć et al, 2016). Specifically, by their nature, encounters between anthropogenic sources (such as tidal turbines) and marine mammals are expected to be infrequent, so long time-series of data would likely be required to meaningfully analyse risk.…”

Acoustic characterization of sensors used for marine environmental monitoring

“…Active acoustic sensors are used for a variety of scientific purposes, including fisheries stock assessment (Fernandes et al, 2002;Simmonds and MacLennan, 2007), water current measurements (Thomson et al, 2012;Vennell, 1994), hydrographic surveys (Lundblad et al, 2006;Wilson et al, 2007), and marine mammal monitoring (Hastie et al, 2014;Lieber et al, 2017;Pyć et al, 2016;Wilson et al, 2007). The operational frequencies used by these sensors are driven by many factors, including scattering physics, acoustic attenuation rates, and study range.…”