Stephen J. Insley

Ringed seals (Pusa hispida) in the Arctic face habitat loss from climate change, making monitoring critical for conservation. Passive acoustic monitoring provides essential data; however, large data volumes require automated analysis. We developed a ResNet-based detector for ringed seal barks in passive acoustic recordings. The detector achieved F1 scores above 0.90 on development data and held-out datasets from different locations and recording periods. In continuous recordings, it maintained high recall (>0.90), with lower precision (∼0.5) reflecting a trade-off between detecting most vocalizations and false positives from acoustically similar non-target sounds. The open-source detector supports large-scale bioacoustic monitoring.

Ringed seals ( Pusa hispida ) use sea ice year‐round in the Arctic as a platform for giving birth, raising young and moulting. Arctic ringed seal population assessments are typically conducted by aerial surveys flown in the spring, when many seals haul out. However, many factors can influence whether a seal is hauled out on the ice and available for detection. Understanding the environmental factors that impact ringed seal haul‐out behaviour will reduce bias in aerial surveys. We deployed camera traps near Ulukhaktok, Northwest Territories, Canada in mid‐May 2023, 2024 and 2025 facing open water leads in the sea ice to document haul‐out behaviour of ringed seals under varying weather conditions. We used generalized additive mixed models to analyse the presence/absence and number of ringed seals hauled out. We found that high temperatures (> −4.3°C), low wind speeds (< 20 km/h), and high barometric pressure systems (101.4–101.8 kPa) increased the probability and number of ringed seals hauling out. We also found that haul‐outs occurred at lower temperatures under conditions of low and moderate wind speeds, and that the number of seals hauled out increased at lower temperatures at low wind speeds. We identify specific ‘ideal weather’ parameters for aerial surveys, which will reduce availability bias when calculating density and abundance estimates.

An analysis of ambient noise data collected from seven locations in the western Canadian Arctic at varying depths (30–350 m) during ice-free seasons over a period of five years (2018–2022) has been conducted. The measured noise level correlates well with wind speed after the removal of contaminated (sources other than wind) noise data. The characteristics of wind noise are predicted by fitting a multi-parameter empirical model to data. Results from the model are compared with existing empirical wind noise models and validated using data collected from one of the measurement locations.

Passive acoustic monitoring is a powerful tool for observing soniferous species in remote marine environments over long periods of time, which can inform conservation planning and wildlife management. In this study, we collected seven months of passive acoustic data from early February to early September 2019 in Minto Inlet, Northwest Territories, Canada, to examine the seasonal presence of four species of marine mammals and unidentified fish species, examine drivers of underwater sound levels, and quantify underwater noise from vessel traffic. Bearded seals were vocally present from mid-March to early July. Ringed seals were present in every month. Beluga whales were present from early July until September. Bowhead whales were detected from April to August, and fish were detected from February to July. Underwater sound levels were dampened by the presence of landfast sea ice and increased with wind speed. Increased bearded seal calls also caused increased sound levels. The only vessel detected was the research vessel that recovered the acoustic recorder. Underwater sound levels were much lower in Minto Inlet compared to other areas in the region, and it appears to be an important site for many marine mammals where forage fish species, primarily Arctic cod, are abundant at depth. These results are in line with Minto Inlet being identified as an important area by the community of Ulukhaktok. At present, anthropogenic impact on this area appears to be very low, but further monitoring is required to determine if any management measures are necessary to maintain these low levels.

Arctic marine mammals face a multitude of challenges linked to climate change, including increasing anthropogenic noise from ship traffic. The beluga whale (Delphinapterus leucas), a predominately Arctic endemic cetacean, relies heavily on acoustic communication, with documented overlap between their vocalizations and hearing range and ship noise. Some belugas migrate through areas with the highest levels of ship traffic in the Pacific Arctic and exposure to ship noise is highly probable. Here, we document the responses of nine satellite‐tagged Eastern Beaufort Sea belugas to encounters with ships in the Beaufort, Chukchi, and Bering Seas during July–December 2018. We report 177 occasions when ships were within 125 km of tagged belugas and quantified changes in lateral and vertical movements to investigate individual behavioral responses to ship approaches within 50 km (n = 23). Belugas' swim speed was negatively correlated with ship distance, showing possible changes in swim speed up to 79 km away. Changes in lateral and vertical movements, indicating disruption of behavior, were observed when some ships passed within 50 km. These findings corroborate previous studies that have shown behavioral responses of belugas to ships at distances far beyond visual range, implying belugas react to low‐amplitude ship noise near ambient levels.

Management of gases during diving is not well understood across marine mammal species. Prior to diving, phocid (true) seals generally exhale, a behaviour thought to assist with the prevention of decompression sickness. Otariid seals (fur seals and sea lions) have a greater reliance on their lung oxygen stores, and inhale prior to diving. One otariid, the Antarctic fur seal (Arctocephalus gazella), then exhales during the final 50–85% of the return to the surface, which may prevent another gas management issue: shallow-water blackout. Here, we compare data collected from animal-attached tags (video cameras, hydrophones and conductivity sensors) deployed on a suite of otariid seal species to examine the ubiquity of ascent exhalations for this group. We find evidence for ascent exhalations across four fur seal species, but that such exhalations are absent for three sea lion species. Fur seals and sea lions are no longer genetically separated into distinct subfamilies, but are morphologically distinguished by the thick underfur layer of fur seals. Together with their smaller size and energetic dives, we suggest their air-filled fur might underlie the need to perform these exhalations, although whether to reduce buoyancy and ascent speed, for the avoidance of shallow-water blackout or to prevent other cardiovascular management issues in their diving remains unclear. This article is part of the theme issue ‘Measuring physiology in free-living animals (Part I)’.

Diet from stomach contents and body condition from morphometric measurements were obtained for 169 (108 stomachs analysed) ringed seals (Pusa hispida) for the Amundsen Gulf region in the western Canadian Arctic from 2015 to 2018. Sampling was from subsistence-harvested seals from the three communities of Paulatuk (spring, summer, and autumn), Sachs Harbour (summer), and Ulukhaktok (winter), Northwest Territories. Stomach contents were separated through sieves and by hand, and taxa identified to the lowest taxonomic level possible and weighed. Stomachs were fullest (by weight and prey count) in the autumn, which suggests that foraging was most intense and successful at that time. A total of 93 prey taxa, including 17 fish and 76 invertebrate species were identified. Several fish and invertebrate species were regularly found together, the most common being Arctic cod (Boreogadus saida), sand lance (Ammodytes hexapterus), capelin (Mallotus villosus), and hyperiid amphipods (Themisto spp.). Condition measurements inferred from blubber thickness, although showing considerable variation among sites and years, had a seasonal relationship with maximal depth during the autumn and winter. Overall, the diet of ringed seals in Amundsen Gulf was broadly similar to those reported from other areas while also indicating some degree of regional specificity. When compared to the diet of ringed seals in the same area in the 1980s, the results presented here were more diverse, with new or increased numbers of subarctic species (e.g., saffron cod, Eleginus gracilis) found in the samples. This finding is a likely consequence of climate warming, as increasing numbers of subarctic species move north with warming ocean temperatures in the Arctic.

The bowhead whale is the only baleen whale endemic to the Arctic and is well adapted to this environment. Bowheads live near the polar ice edge for much of the year and although sea ice dynamics are not the only driver of their annual migratory movements, it likely plays a key role. Given the intrinsic variability of open water and ice, one might expect bowhead migratory plasticity to be high and linked to this proximate environmental factor. Here, through a network of underwater passive acoustic recorders, we document the first known occurrence of bowheads overwintering in what is normally their summer foraging grounds in the Amundsen Gulf and eastern Beaufort Sea. The underlying question is whether this is the leading edge of a phenological shift in a species' migratory behaviour in an environment undergoing dramatic shifts due to climate change.

The soundscape is a crucial habitat feature for marine mammals. This study investigates the contribution of bearded seal vocalizations to the soundscape in the western Canadian Arctic, and also the vocal characteristics of bearded seals relative to sea ice conditions. Passive acoustic data were recorded near Sachs Harbour between August 2015 and July 2016. Sound pressure levels (SPL) in the 50–1,000 Hz and 1–10 kHz bands increased as the total duration of all bearded seal vocalizations increased, and this relationship was moderated by sea ice concentration. Bearded seals in this region had an overlapping vocal repertoire with bearded seals in other areas of the Arctic, and had seven additional vocalizations that have not been previously documented for this region. This study is the first detailed assessment of the influence of bearded seal calls on SPL, which shows the high potential of bearded seals to influence underwater sound levels during the mating season. Bearded seals live in a changing Arctic seascape, and their influence on the soundscape may shift as sea ice continues to diminish. It is imperative that acoustic monitoring continues within the Arctic, and this study provides a baseline for future monitoring as the Arctic continues to change.