Rough-toothed Dolphins appear to be widespread in warm temperate and tropical waters around the world, with an alleged preference for water temperatures ≥25ºC (Miyazaki and Perrin 1994). In the western North Atlantic, the tolerated temperature range may be much wider. Three tagged rehabilitated individuals released off Ft. Pierce, Florida in 2005, swam through waters ranging in temperature from 17–31 °C (Wells et al. 2008).

The species uses diverse habitats, extending from shallow neritic waters, through inshore areas of steep bottom relief to deep oceanic regions, usually beyond the continental shelf (Maigret 1994, Miyazaki and Perrin 1994, Jefferson 2002, West et al. 2011, Kerem 2022).

In the Canary Islands, Rough-toothed Dolphins are observed year-round off the southwestern coast of most islands, with a peak in spring and summer, in water temperatures ranging between 17–19°C in winter and 22–24 ° C in summer (Ritter 2002, Smit et al. 2010, Carrillo et al. 2010, SECAC 2014). Group size ranged from 1-85, including females with calves (Smit et al. 2010, SECAC 2014). Off La Gomera, 53% of groups consisted of adults and/or subadults only, while juveniles and calves were observed in 47% and 16% of groups, respectively (n=83; Ritter 2002). Even in the largest groups, calves and juveniles were present only in small numbers (1–3 per group). In Madeira, calves (single) were present in 17% of groups with known composition (Alves et al. 2018). In the eastern Mediterranean, calves (single) were observed in 15% of the encounters (Kerem et al. 2016).

In the Canaries, they hey were seen at depths ranging from 20 to 2,500 m, sometimes really close to the shore in La Gomera and La Palma, and up to 30 km offshore in Lanzarote and Fuerteventura (Perez-Vallazza et al. 2008, Smit et al. 2010, SECAC 2014). At least some individuals seem to exhibit relatively high levels of site fidelity (Sánchez Mora 2016). In the eastern Mediterranean, sightings occurred at a mean water depth of 1880 km and at a mean distance from shore of 66 km (Kerem et al. 2016). In the Azores, the water temperature was measured in situ of the sighting in August at 24.6–25.2 °C, end of summer being the period when the temperature is >24–25 ºC in the Azores (Steiner 1995).

Rough-toothed Dolphins feed on epipelagic cephalopods and fish (West et al. 2011), including large fish such as Dolphinfish Coryphaena hippurus (Pitman and Stinchcomb 2002). In the Azores, they have been observed feeding on Snipefish Macrorhamphosus scolopax aggregations together with Cory’s Shearwaters (Steiner 1995). Stomach contents of stranded individuals at Gran Canaria contained remains of cephalopods identified as Illex sp., Sepia sp., Garfish Belone belone and Salema Porgy Sarpa salpa (Fernández et al. 2009, Fernández et al. 2022), as well as Bennet's Flying Fish Cheilopogon pinnatibarbatus and Atlantic Bobtail Squid Sepiola atlantica (M. Tejedor pers. comm.). They were observed actively feeding on Flathead Grey Mullet Mugil cephalus inside the Port of Haifa (Kerem et al. 2012). Stomach contents showed the presence of cephalopod (Histioteutidae, Sepiidae) and fish remains, including Narrow-barred Spanish Mackerel Scomberomorus commerson (Kerem et al. 2016).

The Rough-toothed Dolphin is a tropical to subtropical and warm temperate species, which generally inhabits deep, oceanic waters of all three major oceans, rarely ranging north of 40°N or south of 35°S (Jefferson 2002). However, in some areas (such as off the coast of Brazil, Japan, Honduras, West Africa (Mauritania), and the Canary Islands), Rough-toothed Dolphins may occur in more shallow coastal waters. They are found in many semi-enclosed bodies of water (such as the Mediterranean Sea, Gulf of Thailand, Red Sea, Gulf of Mexico, Caribbean Sea, and Gulf of California). The northernmost sighting in the Atlantic is by a US survey ship, 250 km off southern Pennsylvania, ca 39.33 °N (Waring et al. 2014).

Europe
No historical or contemporary record of Rough-toothed Dolphin exists between the Gulf of Cadiz and the Balearic Islands and the only record west of the Ionian Sea or Levantine Basin since the 1980s is from south of Sicily (ACCOBAMS 2021), so that they are considered absent from the western Mediterranean basin. Although they were formerly thought to be seasonal visitors, they are now considered regular in the eastern Mediterranean Sea, east of the Sicily Strait. These dolphins are believed to form a small, relict subpopulation, likely the remnant of a larger one from the Atlantic Ocean and nowadays entrapped in the warm Levantine Basin, in line with their preference for warm temperatures (Kerem et al. 2016). Until further knowledge and survey effort are available, there are two seemingly isolated localities in the Mediterranean subpopulation: the Ionian Sea between south of Sicily and northwestern Greece and the Levant Basin from eastern Libya to the coast of Israel and Lebanon (Kerem et al. 2021).

In European Atlantic waters, they show a latitudinal presence gradient. They are regularly sighted year-round near the southern border in the Canary Islands (Carrillo et al. 2010), are seasonal summer visitors to Madeira Island (Freitas et al. 2012, Alves et al. 2018) and are rarely sighted in the Azores archipelago (Steiner 1995; Espaço Talassa whale-watching team). Four satellite tags were deployed in 2021 and 2022 in Madeira (lasting from 14 to 201 days) and showed that animals travelled extensively in oceanic waters between the three Macaronesian archipelagos and spent little time in proximity to the islands (Alves et al. 2022; F. Alves pers. comm. 2023). This study also found that these same highly mobile oceanic animals spent some time in shallow coastal waters off western Africa in the winter months.

The only known record from mainland Atlantic Europe is a skeleton of an individual stranded in Vilagarcia, Spain in 1979 (Kerem 2022). This suggests that the southern European Atlantic is the northern range of the species in the eastern Atlantic Ocean. Global climate change might increase the habitat suitable for this warmer-water-limited species (MacLeod 2009). This could include a more regular presence in temperate waters of the northeast Atlantic and an expansion towards the western basin of the Mediterranean Sea.

The species is one of the most common delphinids in Cabo Verde, where it is sighted regularly and has been known to be involved in several mass standings (Hazevoet et al. 2010).

The biology, life history, population size, and separation into subpopulations, as well as migratory behaviour are insufficiently known. Research on this species should be encouraged, especially to provide information relevant to update this assessment.

Although not listed on either appendix of the Convention on Migratory Species, Rough-toothed Dolphins are protected by some instruments of this convention, such as the Agreements of ASCOBANS (Baltic, North East Atlantic, Irish and North Seas, https://www.ascobans.org) and  ACCOBAMS (Mediterranean and Black Sea and the adjacent Atlantic area, https://accobams.org/), none of which cover the species' core areas, and the Memorandum of Understanding of Western African Aquatic Mammals (Western Africa and Macaronesia, https://www.cms.int/aquatic-mammals).

The species is listed in Appendix II of the Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention), to which Portugal and Spain are signatory states. In the Canary Islands, several Spanish marine Special Areas of Conservation (SAC) from the Habitat Directive (designed for Bottlenose Dolphins and Loggerhead Turtles) include important areas for Rough-toothed Dolphins, located off the southwest coasts of Tenerife, Gran Canaria, and La Gomera. Thus, even though there are no site-based conservation measures specifically assigned to protect Rough-toothed Dolphins, as their habitat often overlaps with Bottlenose Dolphins, they may be an indirect beneficiary of SACs designated for that species. A detailed plan for the establishment of a full-status MPA in La Gomera, involving all stakeholders, has been advanced by Ritter (2012). If adopted, it too may directly benefit Rough-toothed Dolphins, since together with Bottlenose Dolphins they are the two species most frequently encountered within its proposed bounds. However, as most of their habitat is located in offshore oceanic waters, this will have limited consequences at the population level.