Seasonal and diel acoustic presence of North Atlantic minke whales in the North Sea

Abstract

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 confirmed pulse train presence, subsequently, an automated detector was applied to these data to record the seasonal and diel presence of minke whale pulse trains. Minke whales were detected from May to November, with most detections occurring in June, July and October. No acoustic detections were made in December, January or in the month of April, whilst no data were available for February and March. This pattern of acoustic presence supports available visual data and suggested an absence of minke whales from the study area during winter. Minke whale acoustic presence showed a statistically significant diel pattern, with a detection peak during night time. This study established the acoustic detectability of minke whales in the North Sea and highlights the potential of using passive acoustic monitoring to study the seasonal presence and spatial distribution of minke whales in the North Sea and wider Northeast Atlantic.

Modelling collective navigation via nonlocal communication

“…Specifically, we consider movements of minke whales (Balaenoptera acutorostrata) through portions of the North East 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 [37,38,39]. Sightings become less frequent in the southern North Sea, although seasonal ag-gregations have been observed in the Dogger Bank area near Denmark [40].…”

“…Sightings become less frequent in the southern North Sea, although seasonal ag-gregations have been observed in the Dogger Bank area near Denmark [40]. 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 [41,37]. 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 southwest of Ireland to the west of Norway.…”

Far-Field Effects of Impulsive Noise on Coastal Bottlenose Dolphins

“…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).…”

Common and Antarctic Minke Whales: Conservation Status and Future Research Directions

“…As mentioned above, visual surveys for marine mammals are carried out mostly during daylight and summer months, leaving large data gaps for many species' winter distribution and daily habitat use. Long-term PAM surveys have been shown to be capable in filling some of these gaps and are particularly useful for the study of cryptic species that are difficult to detect visually, such as minke whales (e.g., Risch et al, 2019). Recent advances in digital signal acquisition and processing, increased storage capacity, and reduced power consumption and instrument size means that PAM is increasingly complementing visual surveys of marine mammals (Clark et al, 2010;Gerrodette et al, 2011).…”

“…Tracks of satellite-tagged minke whales indicate a southward movement, following the mid-Atlantic ridge, as far south as at least 28 • N starting in autumn (September to November) (Víkingsson and Heide-Jørgensen, 2015). During summer and early fall (June to November), minke whales in the eastern North Atlantic occur around the British Isles (Macleod et al, 2004;Tetley et al, 2008;Risch et al, 2019) and Norway (Heide-Jørgensen et al, 2001), while their winter distribution remains largely unknown. However, minke whales have been observed year-round around the Canary Islands (van Waerebeek et al, 1999), but only occasionally off Portugal, Spain and West Africa (Aguilar et al, 1983;van Waerebeek et al, 1999).…”