Sowerby’s Beaked Whale has the northernmost range of mesoplodonts in the Atlantic (Bachara et al. 2014). It inhabits deep waters along, or seaward of, the continental slope, including offshore canyons. It can also occur close to shore around volcanic islands with steep seabed topography (e.g. Azores: Silva et al. 2014). In Ireland, the species has been sighted over water depths of 580 to 3,200 m (Berrow et al. 2018).

Strandings in shallow water habitats in the North and Baltic Seas peak during summer and autumn, and have been suggested to reflect seasonal movements northwards in late winter and spring and southwards in the autumn (MacLeod et al. 2004, Stavenow et al. 2022). However, stable isotope analysis indicates that the species displays high regional site fidelity, suggesting that it is unlikely to undertake very long-range movements (Smith et al. 2021a). Year-round acoustic monitoring off the west coast of Ireland recorded Sowerby’s Beaked Whales throughout the year (Kowarski et al. 2018).

The species is considered to be a generalist feeder, preying on a variety of mesopelagic and bathypelagic fish species (Pereira et al. 2011, Wenzel et al. 2013). In Europe, the stomach contents of animals that live-stranded on the coast of Sweden contained fish otoliths from the families Gadidae, Pleuronectidae, Gobiidae and Ostreidae, while eDNA analysis revealed 17 fish species, most commonly Atlantic herring (Clupea harengus) and cod (Gadus morhua) (Stavenow et al. 2022). Gadoid otoliths were also present in a stomach examined in Ireland (Rogan and Hernandez-Milian 2011). Fish dominated the stomach contents of three animals that were stranded on the Biscay coast of France (especially Gadidae: Spitz et al. 2011), and ten animals that were stranded in the Azores (especially Myctophids: Pereira et al. 2011). Histioteuthidae squids were also found in three stomachs in the Azores (Pereira et al. 2011); however, cephalopods appear to be a relatively minor part of the species’ diet, which may reduce resource competition with other mesoplodonts.

Tag deployments on two animals in the Azores indicated that foraging dives last for 29–37 min and can exceed 1,000 m depth, with a maximum recorded depth of 1,386 m (Visser et al. 2022). Prey searches using echolocation began at 400–550 m depth during the descent and concluded at 770–880 m depth on the ascent (Visser et al. 2022). Foraging dives were interspersed by bouts of time spent at shallow (<20 m) depths, during which the whales moved continuously at an overall swimming speed of 2.4 m s-1 (Visser et al. 2022).

Group sizes recorded during sightings in Europe include 1–5 animals in Ireland (Berrow et al. 2018, Rogan et al. 2018), and 2–6 individuals in the Azores (Visser et al. 2022). Single individuals have been seen amongst groups of Cuvier’s Beaked Whale (Ziphius cavirostris) in the Mediterranean (Bittau et al. 2018). Mother-calf pairs have been recorded in strandings in the European region (MacLeod et al. 2004, Bachara et al. 2016, Stavenow et al. 2022), and observed at sea around the Azores (Visser et al. 2022) and off Ireland (Berrow et al. 2018).

Sowerby’s Beaked Whale occurs only in the North Atlantic, where it occupies oceanic habitat in temperate and subpolar regions. Its distribution is primarily documented from strandings. In the eastern Atlantic it occurs from the Canary Islands north to Iceland and the Norwegian Sea. In the western Atlantic, it is distributed from New York (USA) north to Newfoundland and Labrador (Smith and Peterson, In Press).

Within the Pan-European region, densities appear to be highest north of 50 ºN (Kowarski et al. 2018). The majority of records are from Ireland and the U.K. of Great Britain and Northern Ireland (MacLeod at al. 2006, Rogan and Hernandez-Milian 2011, Bachara et al. 2014). The species occurs in deep waters over, and seaward of, the shelf edge, and most sightings and acoustic detections in this region, therefore, occur along the Atlantic seaboard, including the Porcupine Bank slopes, Rockall Trough, and Faroe-Shetland Channel (Weir et al. 2001; Rogan et al. 2017, 2018; Kowarski et al. 2018, Barile et al. 2021). However, there are numerous strandings from the countries bordering the shallow North Sea and English Channel, including the U.K., Norway, Sweden, Denmark, Germany, the Netherlands, Belgium, and France (MacLeod at al. 2006, Bachara et al. 2014, Stavenow et al. 2022). Strandings are also known from the Baltic Sea coasts of Sweden, Germany and Poland (Stavenow et al. 2022). These shallow water habitats are not considered to be part of the core range of the species (MacLeod et al. 2006, Smith and Peterson In Press).

Further north, sightings and strandings have occurred off the Faroe Islands (Bachara et al. 2014), along the Atlantic coast of Norway (Carlström et al. 1996, Stavenow et al. 2022), and around Iceland (Bachara et al. 2014, Grove et al. 2020). The northernmost documented record is at 71.5 ºN in the Norwegian Sea (Carlström et al. 1996). Its occurrence in the Greenland Sea and central Atlantic regions of the European assessment region remains uncertain; it is presumed to occur in at least the latter, but survey effort is lacking.

To the south of the U.K. and Ireland, the species is documented from France (Dabin et al. 2011), the Bay of Biscay (Robbins et al. 2022), Spain (Bellido et al. 2008, Bachara et al. 2016, Covelo et al. 2016), mainland Portugal (Ferreira et al. 2012), the Azores (Silva et al. 2014, Bachara and Barreiros 2016, Visser et al. 2022), and Madeira (Maul and Sergeant 1977, Freitas et al. 2012). The southernmost confirmed records in Europe are in the Canary Islands (29 ºN: Martín et al. 2011). The species has been recently sighted in the Tyrrhenian Sea region of the Mediterranean Sea, close to Corsica and Sardinia (Bittau et al. 2018), and there are strandings (some unconfirmed) on the Mediterranean coasts of France, Italy and Greece (Frantzis et al. 2003, ACCOBAMS 2021). However, it is not considered common in that region (ACCOBAMS 2021). The Mediterranean sightings and strandings on the Andalusian coast (Bellido et al. 2008), strongly support likely occurrence in Gibraltar.

It is listed on Appendix II (strictly protected species) of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention). It is included with all cetaceans on Annex IV Council Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora (the Habitats Directive) as a species requiring strict protection across its entire natural range within the EU. All Mesoplodon species are included in Appendix II (species that are not necessarily threatened with extinction but may become so unless trade is closely controlled) of the Convention on International Trade in Endangered Species (CITES), which requires an export permit or re-export certificate for international trade.

It is included in two regional management agreements in Europe, comprising the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and contiguous Atlantic area (ACCOBAMS), and the Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS). These agreements aim to maintain favourable conservation status of cetacean species within their defined areas, managing threats and working towards the long-term sustainability of populations.