While False Killer Whales occur in tropical, sub-tropical, and at least occasionally in warm temperate waters worldwide (Stacey et al. 1994, Odell and McClune 1999), their density is highest in the tropics (Ferguson and Barlow 2003). They are generally found in relatively deep, offshore waters, but individuals do approach close to shore around oceanic islands (e.g., Hawaii, Macaronesian archipelagos). Distinct insular and offshore populations, with overlapping distribution, have been identified in Hawaiian waters and likely exist in other regions (Baird et al. 2010). Although showing a strong association with the Hawaiian Islands, individuals from resident subpopulation use both shallow (<100 m) and deep (to 4,700 m) waters around the Hawaiian archipelago (Baird 2016). Differences in habitat use have also been identified even between the various social clusters of the Hawaiian insular population (Baird et al. 2012).

Weir et al. (2013) reported several sightings in shallow nearshore shelf waters off Gabon and Côte d’Ivoire (n = 6, range = 17-103 m, mean = 54.5, SD = 30.2)

False Killer Whales eat primarily relatively large fish and cephalopods (Alonso et al. 1999). They have been known to attack and consume small dolphins that have been injured or disoriented when released from tuna purse seine nets in the Pacific Ocean, but this behavior may be more akin to learning to take advantage of opportunistic food sources than to a predilection to feed on other species of marine mammals (Baird 2018). In Hawaiian waters, observational studies suggest that large pelagic game fish (Dolphinfish, tunas, billfishes) form the majority of their diet (Baird et al. 2008, Baird 2016). Depredation data on longline-caught fish suggest a preference for billfishes, Wahoo and tunas over Dolphinfish, pomfrets, Walu, sharks or lancetfishes (Oleson et al. 2010).

Europe
In European waters, limited information is available around Macaronesian archipelagos, and there is a complete gap in offshore waters beyond 12 nm. False Killer Whales off the Azores are well represented in both coastal and offshore waters with intermediate depths (mean: 1200 m, range 700-1700 m, n = 43, Silva et al. 2014). Potential distribution around the Azores archipelago seemed highly influenced by the mid-Atlantic ridge and seamounts or seamount-like structures (Tobeña et al. 2016). This confirms the species’ general preference for deep warm waters and close approaches at oceanic islands.

Yellowfin Tuna Thunnus albacares, Bonito Sarda lineolata, Longspine Snipefish Macroramphosus scolopax, Wreckfish Polyprion americanus, Dolphinfish Coryphaena hippurus and Mullet Chelon labrosus were recorded as prey species in Azorean waters (Steiner et al. 2019). In Madeira, anecdotal observations from whale watching companies showed that False Killer Whales were feeding on large tuna species (P. Gomes, pers. comm. 2022). Stomach content of one animal stranded in the Canary Islands showed a diet composed of six cephalopod species, most of them from the epipelagic zone (Hernández-García 2002).

Cod Gadus callarias remains were found in stranded individuals in the Firth of Tay, Scotland (Peacock et al. 1936). They were also observed feeding on Bluefin Tuna Thunnus thynnus in the Mediterranean Sea (see Calogero et al. 2021).

False Killer Whales are found in tropical to warm temperate zones, generally in relatively deep, offshore waters of the Atlantic, Pacific, and Indian oceans, but they are not common anywhere. Densities are much higher in tropical regions and movements into higher latitudes may be associated with warmer currents, or they could be seasonal (Zaeschmar 2014). False Killer Whales do not generally range into latitudes higher than 50° in either hemisphere and are more common between 40°N and 40°S (Odell and McClune 1999).

The species seems to be uncommon, if not rare, in Cape Verde islands. Only a few strandings and a recent confirmed sighting have been reported so far (Hazevoet et al. 2010, Ryan et al. 2018). Few strandings exist from the Atlantic coast of Morocco from the Strait of Gibraltar to Agadir (Masski and de Stephanis 2018).

Europe
Sporadic stranding and sighting records exist from almost all European waters, including the Mediterranean, Baltic, Irish, North and Norwegian Seas (Zaeschmar and Estrela 2020). However, the species has a preference for warm waters, so that sightings north of the Iberian Peninsula are uncommon. As reviewed by Zaeschmar and Estrela (2020), sighting records north of 45°N include Norway, western Scotland, Aberdeen, the Orkney Islands, the English Channel and the southern Bay of Biscay (Brereton et al. 2001, Evans et al. 2003, Kizska et al. 2007), while strandings were reported in Scotland, Bristol Channel, South Wales, England, Netherlands, Germany and Denmark (Evans et al. 2003, Zaeschmar and Estrela 2020). Out of ~18,000 stranded individuals of 24 cetacean species on the Atlantic coast of France in the Bay of Biscay, no False Killer Whale has ever been recorded between 1969 and 2022 (Dabin 2022).

The species is absent from the Black Sea and they are considered recurring visitors to the Mediterranean Sea with more than 45 sightings around the basin in the last 200 years (Kerem et al. 2012, Dede et al. 2020, ACCOBAMS 2021, Calogero et al. 2021).

In Macaronesia, False Killer Whales are regularly sighted off the Azores with multiple sightings in a year (Silva et al. 2003, 2014, Gomes Pereira 2008, Tobeña et al. 2016, Steiner et al. 2019). Around the Madeira archipelago, the species is considered occasional and irregular (Freitas et al. 2012, Alves et al. 2018). Several sightings of the species have occurred throughout the Canary Islands archipelago (Pérez-Vallazza et al. 2008, Carrillo et al. 2010). According to the Regional government, two strandings of natural causes were recorded in the Canary Islands between 2000 and 2019 (Gobierno de Canarias 2018).

Overall, False Killer Whales do not seem to be abundant over their range in the European assessment area, even where they are relatively regularly sighted such as in the Azores and the eastern Mediterranean. This uncommon presence follows the species general pattern of occurrence throughout its global range, consistent with their transitory presence around oceanic archipelagos and their oceanic and generally nomadic habits.

False Killer Whales are protected from deliberate disturbance, capture or killing under the EU Habitat Directive as all other cetacean species within EU27 waters. Otherwise, no measure taken for the specific purpose of conservation of False Killer Whales currently exists in European waters.

The False Killer Whale is listed in Appendix II of the Convention on International Trade in Endangered Species (CITES). They are not listed on either appendix of the Convention on Migratory Species, but they 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/), and the Memorandum of Understanding of Western African Aquatic Mammals (Western Africa and Macaronesia, https://www.cms.int/aquatic-mammals).