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Spectrogram of a slow-down pulse train recorded off Helmsdale. Spectrogram parameters: fast Fourier transform (FFT) size: 1024 points, overlap: 95%, sample rate: 2000, resolution: 2 Hz and 128 ms. Amplitude scale is relative.
Source publication
Despite frequent records from other parts of the North Atlantic, minke whales have never been
acoustically recorded in the North Sea. This study investigated the detectability of pulse trains
previously associated with this species in other regions, in acoustic data from ten sites along the
east coast of Scotland. Since preliminary results confirme...
Contexts in source publication
Context 1
... 2016 across all ten recording sites in the Moray Firth and along the East Coast of Scotland ( Fig. 1), yielding 340 manually verified positive detection hours. Pulse train characteristics were similar to those described in the Northwest Atlantic 27,28 , with peak frequencies between 50-150 Hz and pulse train durations ranging from 20-60 seconds (Fig. 2). Most pulse trains observed in this data set were slow-down pulse trains, showing a decrease in inter-pulse interval over time 28 ...
Context 2
... of detection hours at Fraserburgh in the southern Moray Firth, where minke whales are frequently observed visually 13,14 was surprising. However, these results may be partly due to the acoustic recorder being placed in very shallow waters at this site. Low frequencies (peak frequencies of minke whale pulse trains are between 150-200 Hz 28 ; Fig. 2) propagate poorly in shallow waters, as these effectively act as high-pass filters 44 ...
Citations
... Conservative estimates of the calling rate of Antarctic minke whales (Balaenoptera bonarensis), presented in [51], indicate a diel pattern with 1.93 calls per hour during daylight hours and 4.09 calls per hour during the night. A similar diel pattern of increased calls during the night was observed in the North Sea and the Northwest Atlantic Ocean for northern minke whales (Balaenoptera acutorostrata) [39,52]. While this is indeed more frequent than the reorientation rate in our model (once per hour, on average), it is possible that the calls are clustered together during certain behaviour, such as group foraging or when a conspecific is within close range [51]. ...
... To allow fixing of certain parameters of the model (e.g. migration speeds and call source levels) we consider data for minke whales (Balaenoptera acutorostrata), which is the most populous species of baleen whale within the North Sea [52,58]. The starting location coincides with previous observations of a significant seasonal aggregation near the Dogger Bank [55] region that peaks in May. ...
Many baleen whales are renowned for their acoustic communication. Under pristine conditions, this communication can plausibly occur across hundreds of kilometres. Frequent vocalisations may allow a dispersed migrating group to maintain contact, and therefore benefit from improved navigation via the “wisdom of the crowd”. Human activities have considerably inflated ocean noise levels. Here we develop a data-driven mathematical model to investigate how ambient noise levels may inhibit whale migration. Mathematical models allow us to simultaneously simulate collective whale migration behaviour, auditory cue detection, and noise propagation. Rising ambient noise levels are hypothesised to influence navigation through three mechanisms: (i) diminished communication space; (ii) reduced ability to hear external sound cues and; (iii) triggering noise avoidance behaviour. Comparing pristine and current soundscapes, we observe navigation impairment that ranges from mild (increased journey time) to extreme (failed navigation). Notably, the three mechanisms induce qualitatively different impacts on migration behaviour. We demonstrate the model’s potential predictive power, exploring the extent to which migration may be altered under future shipping and construction scenarios.
... acutorostrata), is similarly unknown. However, for NAMWs differences in acoustic repertoire have also been found along latitudinal and longitudinal gradients 44,45 . Some observed differences in call type distribution could indicate a shift from summer feeding activity at higher latitudes to presumed winter breeding at lower latitudes 46,47 . ...
... In comparison with AMW data reported here, NAMW vocalisations demonstrate both similarities and differences in dominant call structure between recording locations (e.g. similarities at NE Atlantic and central NW Atlantic locations 44,45,48 ; structural differences between calls recorded at Stellwagen Bank National Marine Sanctuary (SBNMS) in NW Atlantic and the Caribbean 47,49 . However, for both NAMWs and AMWs further studies are needed to clarify geographical variation in call types and repertoire, and to explore their function in the context of minke whale behavioral ecology. ...
Since the attribution of the bio-duck call to Antarctic minke whales (AMW Balaenoptera bonaerensis), different studies have retrospectively identified several bio-duck call types at various sites throughout the Southern Hemisphere. The function of their vocal behavior however, remains largely unknown. Further insights into their repertoire usage may help to reveal the function of their calls. Here, we use passive acoustic monitoring (PAM) data collected across six locations throughout the Weddell Sea (WS) in 2013 and from PALAOA Station (Ekström Ice Shelf, eastern WS) in 2015, 2016 and 2017. In 2013, we detected 11 bio-duck call types throughout the WS between May and December, with additional acoustic activity in February on the western recorder AMW calls fell into four general call clusters. Seasonal patterns of calls showed variability between locations and years. Furthermore, this is the first study to show that similar to other baleen whale species, AMWs also produce songs.
... Although minke whales are a migratory species, their seasonal distribution and migratory patterns are generally poorly understood (Risch et al., 2019a). Common minke whales are mainly present around the British Isles from June to November (Macleod et al., 2004;Risch et al., 2019b;Tetley et al., 2008), but at least some have been recorded every month of the year (Evans, 2019). As would be expected with a northward shift in distribution, the number of strandings in the more northern regions increased over time. ...
Climate change is predicted to impact the distribution of many marine species. In the North-East Atlantic and elsewhere in the world, studies indicate that climate change is leading to poleward shifts in cetacean distribution. Here, strandings data collected in the British Isles from 1990 to 2020 were used to assess whether there is evidence of a shift in baleen whale distribution. Linear regression models were used to compare the number of strandings over time between six regions of the British Isles and, whilst the results indicate no significant change in the number of strandings in the most southerly region of the British Isles, there have been significant increases in more northern regions. Data related to stranded minke whales is the primary driver of these increases, with a number of potential variables affecting this trend, including observer effort. These variables are discussed and further research to explore this potential association is suggested.
... publications: on underwater noise levels (Merchant et al., 2016), cetacean presence and habitat use (Palmer et al., 2019;Risch et al., 2019), and methodological aspects on acoustic monitoring (Williamson et al., 2016;Palmer et al., 2017;Van Geel et al., 2020) (K. Brookes, pers. ...
... Several studies have employed PAM to study habitat use and the effects of offshore construction on cetaceans in UK waters (e.g. Simon et al., 2010;Risch et al., 2019;Thompson et al., 2020;Benhemma-Le Gall et al., 2021). A recent large-scale PAM survey (ObSERVE) off the Irish continental shelf edge, to the south of the Scottish Atlantic Frontier region, obtained new information about the seasonal distribution of 13 cetacean species (eight odontocetes and five mysticetes), and documented offshore seismic survey activity and its effect on marine mammal acoustic detections (Berrow et al., 2018). ...
The characterisation of marine soundscapes allows observation of spatiotemporal distribution of vocalising species and human activities, which can inform an assessment of their interactions. Such data are important for monitoring the ecological status of marine habitats. The Scottish Atlantic Frontier is an important habitat for a variety of cetacean species. Historic whaling has heavily impacted several species inhabiting these waters and current comprehensive information about seasonal occurrence and distribution is lacking for all species. This study presents year-round passive acoustic monitoring data from ten sites in this understudied region. The three most offshore sites were examined for baleen whale vocalisations, and four species were regularly detected. Fin whale detections peaked from October to January and were at their lowest during May and June. Humpback whale song was detected as early as January but showed a strong seasonal peak in March and April. In contrast, minke whales were detected regularly throughout the year but with a peak in detections from October to November, when sei whales were also detected. All monitoring sites showed frequent occurrence of odontocete echolocation clicks and whistles. Comprised mainly of delphinid vocalisations, whistles and clicks were detected on an almost-daily basis among the offshore sites, with a slight reduction in detections from May to July particularly among the more inshore sites. Ambient sound levels (root-mean-square sounds pressure level; SPL) varied by site and season in relation to species presence, anthropogenic contributions, and environmental conditions. Monthly median SPL across the array varied up to 18 dB within 1/3-octave bands. Throughout the year, variability in median SPL was lowest in the higher frequency bands (>10 kHz), while highest variability was found between January to July in specific lower frequency bands (<1 kHz). Results from this study demonstrate the value of passive acoustic data in providing novel baseline information about cetacean occurrence and distribution in Scottish offshore habitats where data are limited and outdated. The results will feed into statutory reporting on underwater noise, support the identification and designation of future marine protected areas for cetaceans, and help guide management of future human-marine mammal interactions in Scottish offshore waters.
... The PSD MMC value of Antarctic minke whales in the BI region is increased at midnight (Figure 6B). Minke whales were observed to be more active in nighttime in Southern Ocean (Menze et al., 2017;Shabangu et al., 2020) and Northern Ocean (Risch et al., 2013(Risch et al., , 2019, owing to the diurnal vertical migration of their prey (zooplankton) into deepwater during the day and to the surface at nighttime (Demer and Hewitt, 1995). However, the seasonal variation in the diel patterns was not significant in our study (Supplementary Figure 5). ...
Deployment of long-term, continuously recording passive-acoustic sensors in the ocean can provide insights into sound sources related to ocean dynamics, air–sea interactions, and biologic and human activities, all which contribute to shaping ocean soundscapes. In the polar regions, the changing ocean climate likely contributes to seasonal and long-term variation in cryogenic sounds, adding to the complexity of these soundscapes. The Korea Polar Research Institute and the U.S. National Oceanic and Atmospheric Administration have jointly operated two arrays of autonomous underwater hydrophones in the Southern Ocean, one in the Terra Nova Bay Polynya (TNBP) during December 2015–January 2019 and the other in the Balleny Islands (BI) region during January 2015–March 2016, to monitor changes in ocean soundscapes. In the BI region, we found distinct seasonal variations in the cryogenic signals that were attributed to collisions and thermal/mechanical fracturing of the surface sea ice. This is consistent with sea-ice patterns due to annual freeze–thaw cycles, which are not clearly observed in TNBP, where frequent blowing out of sea ice by katabatic winds and icequakes from nearby ice shelves generate strong noise even in austral winters. Another advantage of passive acoustic recordings is that they provide opportunities to measure biodiversity from classifying spectral characteristics of marine mammals: we identified 1. Leopard seals (Hydrurga leptonyx; 200–400 Hz), most abundant in the BI region and TNBP in December; 2. Antarctic blue whales (Balaenoptera musculus; distinctive vocalization at 18 and 27 Hz), strong signals in austral winter and fall in the BI region and TNBP; 3. Fin whales (B. physalus; fundamental frequency in the 15–28 Hz and overtones at 80 and 90 Hz), maximum presence in the BI region during the austral summer and spring months; 4. Antarctic minke whales (B. bonaerensis; 100–200 Hz), strongest signals from June to August in the BI region; 5. Humpback whales in TNBP; 6. Unidentified whales (long-duration downsweeping from 75 to 62 Hz), detected in TNBP. Long-term soundscape monitoring can help understand the spatiotemporal changes in the Southern Ocean and cryosphere and provide a means of assessing the status and trends of biodiversity in the Ross Sea Region Marine Protected Area.
... Specifically, we consider movements of minke whales (Balaenoptera acutorostrata) through portions of the northeast Atlantic Ocean, surrounding the British Isles. Minke whales are the most frequently observed whale in these waters, found west of Ireland, off the north and east of Scotland and up to Iceland, Norway and beyond [49][50][51]. ...
... Sightings become less frequent in the southern North Sea, although seasonal aggregations have been observed in the Dogger Bank area near Denmark [52]. Notably, minke whales sightings remain largely confined to the April to October period and it is assumed that the population migrates south to winter in the mid-Atlantic [49,53]. We will consider two case studies of minke whale migration: first, a south to north migration through the North Sea from feeding grounds; second, migration through the East Atlantic Ocean, from the southwest of Ireland to the west of Norway. ...
Collective migration occurs throughout the animal kingdom, and demands both the interpretation of navigational cues and the perception of other individuals within the group. Navigational cues orient individuals towards a destination, while it has been demonstrated that communication between individuals enhances navigation through a reduction in orientation error. We develop a mathematical model of collective navigation that synthesizes navigational cues and perception of other individuals. Crucially, this approach incorporates uncertainty inherent to cue interpretation and perception in the decision making process, which can arise due to noisy environments. We demonstrate that collective navigation is more efficient than individual navigation, provided a threshold number of other individuals are perceptible. This benefit is even more pronounced in low navigation information environments. In navigation ‘blindspots’, where no information is available, navigation is enhanced through a relay that connects individuals in information-poor regions to individuals in information-rich regions. As an expository case study, we apply our framework to minke whale migration in the northeast Atlantic Ocean, and quantify the decrease in navigation ability due to anthropogenic noise pollution.
... The ability to detect and track Odontocetes, particularly porpoise, is far more feasible using PAM than for Mysticetes like Minke that communicate infrequently. Although long-term PAM arrays have been used for detecting seasonal and diel patterns of minke whales in the North Sea (Risch, et al., 2019). ...
Review of monitoring methodologies and technologies, suitable for deployment in high energy environments in Wales, to monitor animal interactions with tidal energy devices. A report produced by Swansea
... The seabed gradually slopes from the coast to depths of up to 200 m and, in the center, there is a shallow sand bank of 40-50 m depth called the Smith Bank (Eleftheriou et al., 2004). The Firth is frequented by a range of cetacean species (Thompson et al., 2015;Robinson et al., 2017;Risch et al., 2019) that includes animals from a protected population of bottlenose dolphins that uses the Moray Firth SAC (Figure 1). The distribution of this population is primarily coastal (Thompson et al., 2015) and, although individuals show interannual variability in their range (Pirotta et al., 2015b), the population shows high site fidelity at a broader scale (Cheney et al., 2014). ...
Increasing levels of anthropogenic underwater noise have caused concern over their potential impacts on marine life. Offshore renewable energy developments and seismic exploration can produce impulsive noise which is especially hazardous for marine mammals because it can induce auditory damage at shorter distances and behavioral disturbance at longer distances. However, far-field effects of impulsive noise remain poorly understood, causing a high level of uncertainty when predicting the impacts of offshore energy developments on marine mammal populations. Here we used a 10-year dataset on the occurrence of coastal bottlenose dolphins over the period 2009–2019 to investigate far-field effects of impulsive noise from offshore activities undertaken in three different years. Activities included a 2D seismic survey and the pile installation at two offshore wind farms, 20–75 km from coastal waters known to be frequented by dolphins. We collected passive acoustic data in key coastal areas and used a Before-After Control-Impact design to investigate variation in dolphin detections in areas exposed to different levels of impulsive noise from these offshore activities. We compared dolphin detections at two temporal scales, comparing years and days with and without impulsive noise. Passive acoustic data confirmed that dolphins continued to use the impact area throughout each offshore activity period, but also provided evidence of short-term behavioral responses in this area. Unexpectedly, and only at the smallest temporal scale, a consistent increase in dolphin detections was observed at the impact sites during activities generating impulsive noise. We suggest that this increase in dolphin detections could be explained by changes in vocalization behavior. Marine mammal protection policies focus on the near-field effects of impulsive noise; however, our results emphasize the importance of investigating the far-field effects of anthropogenic disturbances to better understand the impacts of human activities on marine mammal populations.
... Previous studies have selected data for manual validation based on automated detector counts (per unit time), 11 time (to capture the entire recording period), 4 and location (to capture all recording sites). 12 Given the known variability in automated detector performance that can occur across these variables, 5,13 Fig. 1. Flow chart of ADSV algorithm where N is the predetermined percent duration of acoustic files from the full data set to be included in the manual analysis subset. ...
Passive acoustic monitoring (PAM) can inform wildlife management by providing information on the distribution of cetaceans. This paper presents an automatic data selection for validation (ADSV) method to effectively identify all species acoustically present in large PAM data sets. The ADSV method involves the application of automated detectors, the automated selection of a portion of data for manual review, and the evaluation/optimization of automated detectors. Using an exemplar data set, results from the ADSV method were compared to a more intensive systematic manual review method. The two methods were found to have similar species occurrence results (hourly occurrence matching 73%–100%).
