ABSTRACT. The expansion of hydrocarbon exploration in northwest Greenland has made it increasingly important to understand the occurrence of marine mammals in the region. We describe the seasonal occurrence of marine mammals and the spatial distribution of their calls in Baffin Bay and Melville Bay. Four Autonomous Multichannel Acoustic Recorders (AMARs) were deployed during summer 2012 (late July to early October), five recorders during September 2013, and two recorders from late September 2013 to early September 2014. The call presence of several species was analyzed using automatic call detection and manual verification analysis methods. A novel approach to discern narwhal (Monodon monoceros) clicks from beluga (Delphinapterus leucas) clicks was implemented during the verification process. Narwhal calls were detected in spring and fall, showing a south-to-north migration pattern in spring and a north-to-south migration pattern in fall. Few beluga whales were detected during fall 2013 and spring 2014. Bearded seal (Erignathus barbatus) calls were detected mainly during spring (mating period). A small number of bowhead whale calls (Balaena mysticetus) were detected during fall 2013 and spring and summer 2014. For the first time at this latitude in Baffin Bay, long-finned pilot whales (Globicephala melas) and sperm whales (Physeter macrocephalus) were detected during summer and fall. Our results suggest that the presence of marine mammals in Baffin Bay and Melville Bay is governed mainly by the annual cycle of sea ice formation and decay.

Bearded seal (Erignathus barbatus) calls were recorded using autonomous passive acoustic recorders deployed in the northeastern Chukchi Sea between October 2007 and October 2010. Continuous acoustic data were acquired during summer (August to mid-October), and overwinter data (mid-October through July) were acquired on a duty cycle of 40/48 min every 4 h. We investigated the spatio-temporal distribution and acoustic behavior of vocalizing bearded seals in this multiyear data set. Peaks in calling occurred in spring, coinciding with the mating period, and calls stopped abruptly in late June/early July. Fewer calls were detected in summer, and the vocal presence of seals increased with the formation of pack ice in winter. Vocal activity was higher at night than during the day, with a peak around 0400 (AKST). Monthly patterns in proportional use of each call type and call duration were examined for the first time. The proportion and duration of AL1(T) and AL2(T) call types increased during the mating period, suggesting that males advertise their breeding condition by producing those specific longer trills. The observed seasonal and diel trends were consistent between years. These results improve our understanding of occurrence and acoustic behavior of bearded seals across the northeastern Chukchi Sea.

During breeding season, male harbor seals (Phoca vitulina) produce underwater calls used in sexual competition and advertisement. Call characteristics vary among populations, and within-population differences are thought to represent individual variation. However, vocalizations have not been described for several populations of this widely-distributed and genetically diverse species. This study describes the vocal repertoire of harbor seals from British Columbia, Canada. Underwater recordings were made near Hornby Island during the summer of 2014 using a single hydrophone. A wide variability was detected in breeding vocalizations within this single breeding site. Four candidate call types were identified, containing six subtypes. Linear discriminant analysis showed 88% agreement with subjective classification of call types, and 74% agreement for call subtypes. Classification tree analysis gave a 92% agreement with candidate call types, with all splits made on the basis of call duration. Differences in duration may have reflected individual differences among seals. This study suggests that the vocal repertoire of harbor seals in this area comprises a vocal continuum rather than discrete call types. Further work with the ability to localize calls may help to determine whether this complexity represents variability due to propagation conditions, animal orientation, or differences among individual seals.

Shipping is increasing in Arctic regions, exposing marine mammals to increased underwater noise. Noise analyses often use unweighted broadband sound pressure levels (SPL) to assess noise impacts, but this does not account for the animals' hearing abilities at different frequencies. In 2018 and 2019, noise levels were recorded at five and three sites, respectively, along a shipping route in an inlet of Northern Baffin Island, Canada. Broadband SPLs (10 Hz–25 kHz), unweighted and with auditory weighing functions from three marine mammal groups, were compared between times ore carriers (travelling < 9 knots) were present or absent. Clearly audible distances of shipping noise and exposure durations were estimated for each weighting function relative to vessel direction, orientation, and year. Auditory weighting functions had significant effects on the potential perception of shipping noise. Bowhead whales ( Balaena mysticetus) experienced similar SPLs to unweighted levels. Narwhals ( Monodon monoceros) and ringed seals ( Pusa hispida) experienced lower SPLs. Narwhals were unlikely to clearly perceive shipping noise unless ships were in close proximity (<3 km) and ambient noise levels were low. Detectability propagation models of presumed noise exposure from shipping must be based on the hearing sensitivities of each species group when assessing noise impacts on marine mammals.

Cetaceans spend most of their time below the surface of the sea, highlighting the importance of passive acoustic monitoring as a tool to facilitate understanding and mapping their year-round spatial and temporal distributions. To increase our limited knowledge of cetacean acoustic detection patterns for the east and west coasts of Gwaii Haanas, a remote protected area on Haida Gwaii, BC, Canada, acoustic datasets recorded off SG̱ang Gwaay (Sep 2009–May 2011), Gowgaia Slope (Jul 2017–Jul 2019), and Ramsay Island (Aug 2018–Aug 2019) were analyzed. Comparing overlapping periods of visual surveys and acoustic monitoring confirmed presence of 12 cetacean species/species groups within the study region. Seasonal patterns were identified for blue, fin, humpback, grey and sperm whale acoustic signals. Killer whale and delphinid acoustic signals occurred year-round on both coasts of Haida Gwaii and showed strong diel variation. Cuvier’s, Baird’s, beaked whale and porpoise clicks, were identified in high-frequency recordings on the west coast. Correlations between environmental factors, chlorophyll-a and sea surface temperature, and cetacean acoustic occurrence off Gwaii Haanas were also examined. This study is the first to acoustically monitor Gwaii Haanas waters for an extended continuous period and therefore serves as a baseline from which to monitor future changes.