24 February 2023 | 08:30 - 10:00 (GMT+1)
24 February 2023 | 10:30 - 12:30 (GMT+1)
Open Session - HYBRID
Room: Hörsaal 7
Session Conveners: Kate Stafford (Oregon State University, United States); Karolin Thomisch (AWI, Germany); Heidi Ahonen (Norwegian Polar Institute, Norway); Angela Szesciorka (Oregon State University, United States); Ramona Mattmüller (AWI, Germany)
Global climate change has already had significant observable effects on the environment. Nowhere are the consequences of the Anthropocene epoch more apparent than in the Arctic. Rapid, extreme reductions in Arctic sea ice are driving cascading effects in Arctic ecosystems from physical oceanography to marine predators reliant on a stable, ice-based ecosystem. The impacts from these changes are reflected in the life histories, migratory timing, and biogeographic distribution (i.e., northward expansions or range constrictions) of marine fish, birds, and mammals. An additional consequence is the increasing industrialization of the Arctic, including increases in anthropogenic noise. Rising anthropogenic noise levels are expected to affect acoustically sensitive species like marine mammals, especially in formerly inaccessible Arctic regions. Anthropogenic noise will alter marine soundscapes, can cause a decrease in the acoustic space, or change behavior, energetics and physiology of marine species, including potential population-level impacts as animals are displaced from important foraging or breeding areas. These changes all may impact Arctic inhabitants who rely on many of the marine fish, bird or mammal species for nutritional, cultural and spiritual subsistence. This session aims to bring together the most recent information on these ecosystem transformations, effects of (anthropogenic) noise on marine soundscapes, evidence of phenology adaptations, and on-going borealization of the Arctic. Towards end of the session, we have reserved time for open discussion on pan-Arctic PAM effort and best practices.
Session 1 (08:30 - 10:00 GMT+1):
unfold_more08:30 - 08:35: Introduction to Session 1
Angela Szesciorka; Kathleen Stafford
unfold_more08:35 - 08:55: Sea ice directs changes in bowhead whale phenology through the Bering Strait
Angela Szesciorka1; Kathleen Stafford1
1Oregon State University
Climate change is warming the Arctic faster than the rest of the planet. Shifts in whale migration timing have been linked to climate change in temperate and sub-Arctic regions, and evidence suggests Bering-Chukchi-Beaufort (BCB) bowhead whales (Balaena mysticetus) might be overwintering in the Canadian Beaufort Sea. We used an 11-year timeseries (spanning 2009 to 2021) of BCB bowhead whale presence in the southern Chukchi Sea (inferred from passive acoustic monitoring) to explore relationships between migration timing and sea ice in the Chukchi and Bering Seas. Fall southern migration into the Bering Strait was delayed in years with less mean October Chukchi Sea ice area and earlier in years with greater sea ice area (p = 0.04, r2 = 0.40). Greater mean October–December Bering Sea ice area resulted in longer absences between whales migrating south in the fall and north in the spring (p < 0.01, r2 = 0.82). A stepwise shift after 2012-2013 shows some whales are remaining in southern Chukchi Sea rather than moving through the Bering Strait and into the northwestern Bering Sea for the winter. Spring northern migration into the southern Chukchi Sea was earlier in years with less mean January–March Chukchi Sea ice area and delayed in years with greater sea ice area (p = 0.002, r2 = 0.823). As sea ice continues to decline, northern spring-time migration could shift earlier or more bowhead whales may overwinter at summer feeding grounds. Changes to bowhead whale migration could increase the overlap with ships and impact Indigenous communities that rely on bowhead whales for nutritional and cultural subsistence.
unfold_more08:55 - 09:15: Seasonal distribution of sperm whales in the High Arctic revealed by multi-year passive acoustic monitoring
Viivi Pöyhönen1; Heidi Ahonen2; Kit Kovacs2; Karolin Thomisch3; Christian Lydersen2
1Lund University; 2Norwegian Polar Institute; 3Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research
The sperm whale (Physeter macrocephalus) is a cosmopolitan species with a broad distribution that ranges from the tropics to the poles. Males migrate between nutrient-rich high latitude waters and low latitude breeding grounds. In the North Atlantic, large males are found up to the southern limits of the ice edge. However, their seasonal distribution patterns remain poorly known in the High Arctic. This study used passive acoustic data collected from nine different locations around Svalbard Archipelago from 2012 to 2021. An automated detector was designed and implemented using PAMGuard to identify time periods containing sperm whale vocalizations. Automatic detection results were then manually confirmed; different click types were also scored, and the number of vocalizing individuals was estimated. The results indicate sperm whale hotspots along the ice-free portion of eastern Fram Strait (along the shelf break) and close to the coast of western Spitsbergen from May to January, with some variation between years and moorings. Although the acoustic presence decreased further north, even the northern-most location (81°N) had sperm whales present from August to as late as January during no or low ice periods of the year. Sperm whale click detections were less frequent in fjord locations and off the east coast of Svalbard. This study is a first multi-year acoustic assessment of sperm whale distribution in the High Arctic. It provides valuable baseline information on the distribution of sperm whales, a migratory species that is frequently present in the High Arctic. Such knowledge is interesting in the context of understanding and predicting future patterns of cetacean distribution in the rapidly changing Arctic marine environment.
unfold_more09:15 - 09:35: Acoustic classification of belugas and narwhals using echolocation clicks with implications for passive acoustic monitoring
Marie J. Zahn1; Shannon Rankin2; Jennifer L. K. McCullough3; Jens C. Koblitz4; Frederick Archer2; Marianne H.Rasmussen5; Kristin L. Laidre1
1University of Washington; 2National Marine Fisheries Service, NOAA; 3Pacific Islands Fisheries Science Center, NOAA; 4University of Konstanz; 5Húsavík Research Centre
As the only endemic toothed whales in the Arctic, belugas (Delphinapterus leucas) and narwhals (Monodon monoceros) use high-frequency echolocation clicks to forage and navigate. Passive acoustic monitoring (PAM) programs that capture year-round species occurrence are becoming increasingly important to understand beluga and narwhal habitat-use changes as the Arctic warms and underwater anthropogenic noise increases. Here, we present research showing that belugas and narwhals can be acoustically differentiated and classified solely by echolocation clicks. Acoustic recordings were made in the pack ice of Baffin Bay, West Greenland. Multivariate analyses and Random Forests classification models were applied to eighty-one single-species acoustic events comprised of numerous echolocation clicks. Results demonstrate a significant difference between species’ acoustic parameters where beluga echolocation was distinguished by higher frequency content. Spectral peaks, troughs, and center frequencies for beluga clicks were generally > 60 kHz and narwhal clicks < 60 kHz with overlap between 40–60 kHz. Classification model predictive performance was strong with an overall correct classification rate of 97.5% for the best model. Our results provide strong support for the use of echolocation in beluga and narwhal PAM efforts particularly because their social calls are highly variable and can be challenging to classify.
unfold_more09:35 - 09:55: A robust method to automatically detect fin whale acoustic presence and airgun pulses in large and diverse passive acoustic datasets
Elena Schall1; Olaf Boebel1
1Alfred-Wegener-Institute for Polar and Marine Research
The growing availability of long-term passive acoustic recordings opens the possibility of monitoring the vocal activity of elusive oceanic species, such as fin whales (Balaenoptera physalus), to study their distribution, behavior, population structure and abundance. At the same time, these recordings also contain anthropogenic sounds, such as low-frequency airgun pulses generated during seismic explorations. Both fin whale vocalizations and airgun pulses are short and high-intensity impulse signals. The manual screening of extensive passive acoustic recordings for such signals by human experts is, however, time-consuming and often suffers from low reproducibility, rendering manual screening a rather unpractical method. Here, we present robust computational algorithms for the automatic detection of fin whale and airgun pulses which yield good performance results (i.e., false positive rates < 1 % and true positive rates > 78 %) when applied to a diversity of Southern Ocean soundscape recordings characterized by low occurrences of the target signals. Impulse signals are differentiated based on their spectral limits and can be simultaneously detected in a dataset as long as these limits are not equal. The presented algorithms are useful tools to simultaneously monitor fin whale acoustic presence and airgun noise in both the Southern and the Arctic Ocean, while these algorithms further show potential for broader applications to detect impulse signals of all kinds.
Session 2 (10:30 - 12:30 GMT+1):
unfold_more10:30 - 10:35: Introduction to Session 2
Karolin Thomisch; Ramona Mattmüller; Heidi Ahonen
unfold_more10:35 - 10:55: Two sides of Svalbard: Underwater soundscape and marine mammal community characterized through acoustic data
Samuel Martinez Llobet1; Heidi Ahonen1; Christian Lydersen1; Kit Kovacs1
1Norwegian Polar Institute
The Svalbard Archipelago is warming fast, leading to environmental changes that are likely affecting the underwater soundscape, a critical habitat feature for marine fauna. Baseline information about sound levels is necessary to monitor future changes in the region. We used fixed-location recorders to characterize the soundscape and study marine mammal occurrence and phenology at three locations around Svalbard. Kongsfjorden (2017-2018), on the west coast, has undergone vast environmental change, whereas locations M1 and M2 (2019-2021), on the east coast remain more Arctic. Our results reveal that the soundscape and the species assemblage differed between the two sides of Svalbard. In the west, Arctic species were detected from winter to summer and migrant species were detected occasionally through the autumn. In the east, Arctic species were detected constantly almost year-round and a few migrant species were detected during summer. Vessels were acoustically detected more often in the west than in the east, in accordance with the AIS traffic data indicating a higher number of boats near the recorder in Kongsfjorden. In terms of soundscapes, geophonies (wind, ice) were the main factors determining the sound energy at all locations. Kongsfjorden’s soundscape was characterized by glacier-melt sounds with moderate levels of anthropogenic noise and some biophonies (marine mammals). At M1 and M2, sea-ice noise shaped the soundscape, which was dominated by biophonies from marine mammals; at these sites there was little impact from anthropophonies (vessels). This study provides baseline information on Svalbard’s soundscape, which is likely to be transformed in the future due to ongoing climate change.
unfold_more10:55 - 11:15: Listening to changes in marine mammal biodiversity in the Arctic
Oregon State University
The Pacific Arctic Region (PAR), which includes the Bering Strait, and Chukchi and Beaufort Seas, is a bellwether for climate change in the Arctic with sea ice extent and thickness decreasing and freshwater and heat content increasing. The biological responses to these extreme physical changes are complex but may result in ecosystem shifts from primary productivity to upper trophic predators. To observe the response of upper trophic level species via changes in occurrence and/or distribution over both temporal and spatial scales, passive acoustic recorders were deployed on three ecosystem moorings in PAR hotspots: the northern Bering Sea off western St Lawrence Island, in the Chukchi Sea at Hanna Shoal, and on the shelf break of the western Beaufort Sea. The furthest south hydrophone (Bering Sea) had the greatest seasonal occurrence of both subarctic and Arctic species; while these species suites had peak occurrences during different seasons, there was nevertheless extensive overlap in early winter of fin, humpback and bowhead whales. This overlap and overall community compositions decreased further north such that the only subarctic species detected in the Beaufort Sea was killer whales which have extended their distribution north- and eastwards into the Beaufort. Arctic endemic species bowhead and beluga whales were each detected later in the fall and winter and earlier in the following spring along their migratory routes in the Chukchi and Beaufort Seas. Changes in marine mammal biodiversity both in space and time may be leading to large-scale shuffling of subarctic and Arctic marine animal communities as high-latitude marine ecosystems undergo rapid reorganization
unfold_more11:15 - 11:20: Introduction to Session 3
unfold_more11:20 - 11:40: Discussion: CAFF Arctic PAM network
unfold_more11:40 - 12:10: Discussions: OPUS - An Open Portal to Underwater Soundscapes to explore sound in the global ocean
unfold_more12:10 - 12:30: Questions and wrap-up