Beaked Whales

Cuvier’s beaked whale

Life history

Females reach sexual maturity at around 5.8 m and males at 5.5 m. Reports on the oldest aged individual span from 28 to 30 in females and 36 to 47 years in males (Baird et al. 2018, Ross 2006).

Social interactions

Group sizes are usually small and lone individuals, often males, are not uncommon (Baird et al. 2018, Ross 2006).

Cuvier’s beaked whales in the Ligurian Sea

Sound and communication

Cuvier’s beaked whales are a highly vocal species which produces lots of high-frequency clicks when hunting. However, Cuvier’s beaked whale seems to be completely silent in the upper water column above 500m depth. This is believed to be a predator avoidance behaviour, as it makes them very hard to detect from a distance (Tyack et al. 2006).

Diving and swimming

Cuvier’s beaked whales are known as extreme divers, although behavioural data from this difficult-to-study species are limited.

A study found that Cuvier’s beaked whale, on average, dive to 1888 metres for extended periods of up to 85 minutes (Tyack et al. 2006). In 2011, a tagged Cuvier’s beaked whale dove to 2,992 m, which is the deepest recorded dive by any mammal. The longest dive recorded during the study lasted for 137,5 minutes (Schorr et al. 2014).

Cuvier’s beaked whales swimming near Savona in the Ligurian Sea

Food and feeding

Cuvier’s beaked whales usually prey on many different cephalopod species, but primarily on large specimens of squid (MacLeod et al. 2003). They find their prey in the deep ocean waters using echolocation; a sequence of high-frequency click sounds that are sent into the environment. They then use suction feeding to catch their prey (Heyning and Mead 1996).

Predators

This species has no known predators. It may be presumed that orcas could be a predator, however, predation is made difficult by Cuvier’s beaked whales emitting no sounds in the top 500 m of water depth.

Strandings

Strandings of dead Cuvier’s beaked whales have been associated with naval exercises all over the globe. They are the species most often stranded in association with Mid-Frequency Active (MFA) sonar use, a relationship that remains poorly understood (D’Amico et al 2009) – for more information see section on noise.

In 2017, a Cuvier’s beaked whale stranded on Vindenes, Fjell, Sotra Island, in the Hordaland county of the Vestlandet region of the Norwegian coast. The whale was an adult female, 6.25 m long and weighed around 2 tonnes (Bachara and Øien 2017). This was only the second recorded Cuvier’s beaked whale to have stranded in Norway. The cause of death for this individual was not established.

Distribution and habitat

Distribution

Cuvier’s beaked whale distribution ©Pcb(talk) after Vardion

The Cuvier’s beaked whale has the largest distributional range of all ziphiids. It is found in offshore waters of all oceans, from tropical to polar regions oceans. It is not found in very high-latitude polar regions or shallow water areas. These whales are common in the North-East Atlantic but are absent from the Baltic sea. It is also the only species of beaked whale regularly found in the Mediterranean Sea.

Movements and migration

Despite their extensive distribution range, studies show long-term site fidelity (philopatry) and local adaptations in Cuvier’s beaked whales (McSweeney et al. 2007, Hoelzel 1998). The global assessment of Cuvier’s beaked whales’ genetic diversity suggests that there is probably little movement of the whales among different ocean basins and that there may even be a distinct subpopulation in the Mediterranean Sea (Dalebout et al. 2005).

Stocks and abundance

Worldwide

Cuvier’s beaked whales are undoubtedly among the most common and abundant of all the beaked whales and worldwide abundance is likely to be well over 100,000 (Taylor et al. 2008).

North Atlantic

By combining the data from three surveys (2005 SCANS-II, and 2007 CODA and Faroese area of T-NASS) Rogan et al. (2017) suggest an abundance of 2,286 Cuvier’s beaked whales (CI: 95%: 942–5,552) for the area. This abundance estimate is the first-ever for these waters (see section on abundance in the general introduction of beaked whales for an illustration) and gives researchers a better understanding of the abundance of this deep-diving species in the North-East Atlantic.

Specific management measures

In 2004, the Parties to the UNEP CMS Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS) adopted a resolution recommending avoiding activities generating high-intensity noise in areas with a high abundance of Cuvier’s beaked whales.

Human impacts

Human removals: hunt & by-catch

The species has not been hunted in the North Atlantic, although it has been taken opportunistically in other direct fisheries in the Caribbean islands, as well as in the oceans around Peru, Chile, Indonesia, Japan and Sri Lanka (Taylor et al. 2008).

Cases of Cuvier’s beaked whale being by-caught have been reported in different fisheries, including the Italian swordfish fishery (Taylor et al. 2008), although by-catch in the North-East Atlantic seems very low, if not absent.

Noise

Cuvier’s beaked whales have proved to be extremely sensitive to noise disturbance (Schorr et al. 2014). Strandings of Cuvier’s beaked whales, either single or en masse, were very rare until the 1950s. However, as the use of sonar was introduced in vessels (industrial, research and military), the prevalence of stranding events has risen greatly (Ketten 2014, Bernaldo de Quiro’s et al. 2019).

Cuvier’s beaked whale is the dominant species in mass stranding events and several mass strandings of this species have occurred in the North Atlantic in recent decades. This includes events in the Mediterranean Sea during 1996 (Frantzis 1998), the Madeira Islands in 2000 (Frietas 2004), and the Canary Islands in 2002 (Jepson et al. 2003). These mass strandings have been related to behaviour to avoid sonar disturbance (Aguilar de Soto et al. 2016, New et al. 2013, Cox et al. 2006).

Within the North-East Atlantic, three mass stranding events have occurred around the British Isles in recent decades. In 2008, 18 Cuvier’s beaked whales stranded along the coastline over seven months (Dolman et al. 2010). In December 2014/January 2015 five stranding events were documented (Brownlow et al. 2015). The latest event happened between July and October of 2018 where 83 Cuvier’s beaked whales stranded along the coastline of the Isles. During the latest mass stranding event, there was also an increase in the observed number of live or dead strandings of beaked whales (15 individuals) reported in Iceland, which was believed to be connected to the strandings along the British and Irish coastlines. This lead to a total of 102 Cuvier’s beaked whale strandings in 2018 (Brownlow et al. 2019).

Mesoplodon

Male Blainville’s beaked whale © Oregon State University

The Mesoplodon beaked whales include 14 species that are all small to medium-sized. They are rarely positively identified at sea and their life history, behaviour and ecology is very poorly understood. Some have a wide distribution over several ocean basins, while others have restricted ranges. Lifespans are often unknown, but are likely relatively long, i.e. 20+ years. Females are sexually mature at 8-10 years of age. The breeding season is believed to be from late winter to spring. Females give birth to a single calf (Pitman, 2018). Gestation periods are unknown but thought to be 12 months in most species.

Blainville’s beaked whale

Morphology

Mother and calf pair of Blainville’s beaked whales © Matthew Grammatico

Blainville’s beaked whales reach 4-6 m in length and weigh 800-1000 kg. They have a large dolphin-like body with a flattish forehead and an indistinct melon. Like other beaked whales, males have tusks and extensive scarring. The strongly arched lower jaw and the protruding tusk gives adult males a very unique profile. The tusk-like teeth are also sometimes covered with barnacles. This species has the densest bone ever described and is often referred to as the ‘dense-beaked whale’ (Ellis and Mead 2017).

Life history

Females are believed to be sexually mature at around 9 years of age (Pitman 2018). Newborn calves are about 1.80 to 2.5 m long and weigh about 60 kg.

Behaviour

Individual males tend to be found alone or in small groups, while females with calves seem to prefer to associate in larger groups, consisting of multiple adult females. Larger groups typically only have one male present. This, combined with the scarring in males, is suggestive of some form of female defence polygyny within this species (Hooker et al. 2019). Studies of association patterns suggest that male-female associations might last for at least a year (Dunn 2015, Hooker et al. 2019).

Diving and feeding

The dives performed by Blainville’s beaked whales usually last between 20 – 45 minutes and can commonly reach depths of at least 500 to 1000 m. However dives of over 54 minutes and up to 1400 m have also been recorded (Jeffersen et al. 2008). While diving, they use the strategy of suction feeding to prey on small fish and cephalopods (e.g. squid) in deep water.

Distribution and habitat

Blainville’s beaked whale distribution © Alessio Marrucci

The Blainsville’s beaked whale has one of the widest distributional ranges, although it extends less towards higher latitudes than the Cuvier’s beaked whale. It is found in tropical and temperate oceans in both hemispheres and in continental slope waters of intermediate depth (between 200 and 1,000 m). It can also occur in coastal waters around oceanic islands. The species occurs in many enclosed seas with deep waters, but there are only rare records from the Mediterranean and the species is therefore probably a vagrant species there (Taylor et al. 2008).

Very little is known about this species, except off the northeastern Bahamas where the animals are particularly well documented through long-term studies. These studies have been conducted since the 1990s and offer a wealth of information on the ecology of that population (Claridge 2013).

Abundance

Overall, the species appears to be fairly common in most tropical seas, although it is not considered to be common throughout the whole distribution area per se (Ellis and Mead 2017). It is one of the most common of all the species of Mesoplodon. Abundance estimates only exist for a few areas and no estimate is currently available in the NAMMCO area.

Threats

Blainville’s beaked whales have been and are opportunistically taken in artisanal fisheries in various areas, but likely not in the North Atlantic.

As for other beaked whales, there is an increasing concern that loud underwater sounds, such as active sonar and seismic operations, may be harmful and the use of active sonar from military vessels has been implicated in mass strandings of Blainville’s beaked whales (e.g. Jepson et al. 2003, Taylor et al. 2008).

This species will face many of the same threats from human activities described for beaked whales in general. For example, some stranded specimens have been found with plastic in their stomachs indicating that marine pollution can pose a potential threat.

Conservation and management

See the Conservation and Management section under general information.

Mesoplodon

Sketch of Sowerby’s beaked whale male © Thorburn, Archibald

The Mesoplodon beaked whales include 14 species of beaked whales all small to medium-sized and rather unknown. They are rarely positively identified at sea and their life history, behaviour and ecology is very poorly known. Some have a wide distribution over several ocean basins, some have restricted ranges. Lifespans are often unknown, but likely relatively long of 20+ years. Females are sexually mature at 8-10 years of age. Their breeding season is believed to be from late winter to spring. Females give birth to a single calf (Pitman, 2018).  Gestation periods are unknown but thought to be 12 months in most species.

Names

The name Mesoplodon roughly translates to armed with a tooth in the centre of the jaw in greek, mes-mesos = middle, -opl-, hoplon = tool, weapon, and -odon, odous = tooth. The presence of this tooth is a well known characteristic for all beaked whales.

General characteristics

Sowerby’s beaked whales have a torpedo body shape, which is classic for the Mesoplodon genus. This species was first described in 1804 based on the finding of a jawbone (Ellis and Mead 2017).

Sketch of the skull of an adult male Sowerby’s beaked whale with the erupted tusk clearly visible © Royal Natural History

They are characterised by the single pair of teeth protruding midway along the jawline. The small triangular dorsal fin is placed two thirds of the way down the back and the species has narrow pectoral fins. They are bluish-grey in colour with light brown colouration on the head and beak and countershading on the ventral side (i.e. on the belly). As for all other beaked whale species, adult individuals – predominantly males – have extensive scarring patterns. Apart from dentition differences, there is little sexual dimorphism in this species (Mead 1989).

Life history and ecology

Life history

Adult individuals can reach between 5 – 5.5 m in length and can weigh up to 1.3 tonnes. Virtually nothing is known about the life hisotyr of the Sowerby’s beaked whale. Offspring/young are around 2.4-2.7 meters at birth and weigh about 185kg, i.e., about 40-50% of the mother’s size.

Social interactions

This species is usually found in pairs or in pods up to ten individuals of mixed age and sex.

Diving and swimming

Sowerby’s beaked whales have been observed bringing their entire beak out of the water when they surface. This is often done at a steep 45^○ angle (Hooker and Baird 1999, Pitman 2018). Sowerby’s beaked whale usually exhibits little surface behaviour, but tail-slapping, breaching and spy-hopping have been observed (Hooker and Baird 1999).

Sowerby’s beaked whale, like most other Mesoplodon species, perform deep dives. Foraging dives of up to 28 minutes have been recorded, with whales only staying at the surface for a few minutes in between (Culik 2003).

Food and Feeding

Like other beaked whales, Sowerby’s beaked whales use suction feeding. Their prey mostly consists of midwater fish, deep-water squid, and molluscs (Pereira et al. 2011, MacLeod et al. 2003, Ostrom et al. 1993).

Predators

Orcas and large sharks are likely predating on this species.

Distribution and habitat

Sowerby’s beaked whale distribution © Alessio Govi

Distribution

The Sowerby’s beaked whale is found exclusively in the North Atlantic and inhabits temperate to subarctic Atlantic waters, from the American/Canadian east coast (up to Newfoundland and Labrador) to Iceland and the Norwegian Sea, and south to Madeira and Morocco (Cosewic 2006). Sowerby’s beaked whale is the most northernly distributed Mesoplodon species with a southern limit at around 30°N. (Macleod 2000), although its presence is uncertain in Greenlandic waters (Taylor et al. 2008).

Habitat

Even though the species is well described from strandings, little knowledge is available about their habitat as they are seldom observed in the wild (Culik 2003). They have been mostly observed offshore in the deep waters beyond the continental shelf in the North Atlantic ocean (MacLeod 2000).

Did you know?

Of all the Atlantic species of Mesoplodon this is the one with the most northerly distribution, with sightings as far as 71°N in the Norwegian Sea (Carlstrøm et al. 1997)

Movements and migration

There is little knowledge regarding the migration pattern of Sowerby’s beaked whales. It is unknown if individuals move between the east and west Atlantic (Cosewic 2006).

Abundance and trends

Their overall abundance and stock structure is unknown, but Sowerby’s beaked whales are not believed to be uncommon and are one of the most common Mesoplodon species in some areas of the North Atlantic.

The first-ever overall abundance of Sowerby’s beaked whales for the oceanic and shelf waters of the North-East Atlantic was obtained by combining the data from three surveys (2005 SCANS-II, 2007 CODA, and Faroese T-NASS, see Figure 2 in the general introduction). It generated an abundance of 3,518 (CI 95%: 1,570–7,883) for the surveyed area (Rogan et al. 2017).

The habitat and abundance of Sowerby’s beaked whale are overall too poorly known to speculate on trends (Taylor et al. 2008).

Human impacts

There is little specific information on the threats to this species (Reeves et al. 2003).

Human removals: hunt & by-catch

Sowerby’s beaked whales were incidentally killed by whalers in Newfoundland, Iceland, and in the Barents Sea. A few entanglements in fishing gear (e.g., driftnets) have been documented. Waring et al. (2001) reported that from 1989-1998, the observed by-catch in pelagic drift gillnets along the US East Coast included 24 Sowerby’s beaked whales.

Drawing of Sowerby’s beaked whale © Biodiversity heritage library

Strandings

This is the most common Mesoplodon species recorded in stranding events. On the Irish coast, there have been ten reported strandings of Sowerby’s beaked whales since 2004 (McGovern et al. 2016). Although the cause of death is often not established, in 2018 a Sowerby’s beaked whale was necropsied and the cause of death was determined to be boat/ship strike (Brownlow et al. 2018).

Noise/disturbance

Since they hunt at great depths, Sowerby’s beaked whales (as all other beaked whales), are vulnerable to anthropogenic noise such as military mid-range sonar and seismic surveys. Individuals of other Mesoplodon species stranded in spatial and temporal proximity to military exercises have displayed pathology matching gas-bubble disease, which led to the hypothesis of abnormal diving behaviour in these specimens due to noise disturbance (Cox et al. 2006, Tyack et al. 2006, COSEWIC 2008).

Climate change

Climate change will have different impacts on different cetacean species according to their distribution, habitat and prey. As Sowerby’s beaked whale is a temperate/subarctic species, depending on a specific group of deep-sea prey species, the consequences for this species are highly correlated to the consequences for the squid they feed upon.

Conservation and management

The species is designated as “Special Concern” by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).

For more on the conservation and management of beaked whales in the North-East Atlantic, see the section on Conservation and Management under general information.

Mesoplodon

Mesoplodon includes 14 species of beaked whales, which are all small to medium-sized. They are rarely positively identified at sea and their life history, behaviour and ecology is very poorly known. Some have a wide distribution over several ocean basins, while others have restricted ranges. Lifespans are often unknown, but are likely relatively long (20+ years). Females are sexually mature at 8-10 years of age. Their breeding season is from late winter to spring. Females give birth to a single calf (Pitman, 2018). Gestation periods are unknown but believed to be 12 months in most species.

Names

The name Mesoplodon roughly translates to armed with a tooth in the centre of the jaw in greek, mes-mesos = middle, -opl-, hoplon = tool, weapon, and -odon, odous = tooth. The presence of this tooth is a well known characteristic for all beaked whales.

Morphology

True’s beaked whale is characterised by a slightly bulbous forehead (melon), a prominent short beak, and teeth (measuring around 5cm) located at the tip of the lower jaw and angling forward (Pitman 2018). The scarring pattern of male True’s beaked whales is predominantly parallel and linear, with small gaps between adjacent scars. The pectoral fins are short and the dorsal fin is small, triangular and placed two thirds of the way down the back.

Regional differences

True’s beaked whales are greyish in colouration and usually have a darker patch around the eye and lighter colouration on the head and ventral side. There is some regional variety, both within and between the populations in the northern and southern hemispheres. True’s beaked whales in the North Atlantic are described as almost uniformly greyish in colouration. Individuals have been observed with both a dark eye mark and a dark blaze from behind the blowhole to past the dorsal fin. Some animals may exhibit a pale colouration on the ventral side (the underside), which sometimes extends to the lower jaw. Some animals may also have a pale blaze on their melon (Weir et al. 2004,  Jefferson et al. 2015). In contrast, observations in the southern hemisphere have shown a female with more whitish colouration on the dorsal side, extending from the dorsal fin to the tail peduncle (Aguilar de Soto et al. 2017).

The differentiation in colouration has led researchers to question whether the animals in their respective hemispheres are genetically isolated and might represent different species (Dalebout et al. 2007, Macleod et al. 2006). Indeed, some degree of a phylogeographic pattern has been detected in the genetic structure (i.e. considering the geographic distribution of individuals in light of population genetics) (Aguilar de Soto et al. 2017). With the ecology and population structure of True’s beaked whale being virtually unknown, genetic studies are an important contribution to research on this species. The scarcity of information on the species is re-enforced by the rarity of live sightings. The first-ever video recording of this species was in the Azores in 2017 (Aguilar de Soto et al. 2017) and the first photos were taken in the Bay of Biscay area in 2017 (Robbins et al. 2019).

This video shows the first-ever recording of True’s beaked whale in the Azores in 2017 (Aguilar de Soto et al. 2017). Video credit: Roland Edler.

Life history and ecology

Life history

Adult individuals reach around 5 m in length and weigh up to 1.4 tonnes. There is virtually no knowledge about the life history of True’s beaked whale, but offspring/young are around 2-2.5 m at birth i.e., about 40-50% of the mother size.

Social interactions

This species is usually found in pairs or small pods. Males are believed to interact in male to male aggressive behaviour, as adult individuals exhibit a pattern of parallel linear scarring.

Diving and swimming

True’s beaked whale usually exhibits little surface behaviour, although repeated breaching has been observed in the Canary Islands (Aguilar de Soto et al. 2017). This species, like most other Mesoplodon species, perform deep foraging dives.

Food and feeding

Like other beaked whales, True’s beaked whales use suction feeding. Their prey is predominantly deep-water squid of the Loligo spp (MacLeod 2005).

Stable isotope analysis has found that this species feeds at a similar trophic level to other  Mesoplodon species with which it is sympatric (two related species or populations coexisting in the same geographic area), but at a lower trophic level than Cuvier’s beaked whale and the northern bottlenose whale. This suggests that True’s beaked whale feeds on smaller prey than the two latter species (MacLeod 2005).

Predators

Orcas and large sharks are likely predating on this species.

Distribution and habitat

True’s beaked whale distribution © Alessio Marrucci

Distribution

Global

The distribution range for this species is unique among Ziphiids as they are found in two distinct zones. There is one northern distribution in the temperate part of the Atlantic Ocean and a southern distribution in the temperate South Atlantic (strandings in Brazil and South Africa) and the South Indian Ocean, with no confirmed sightings in between. Until 1969, this species had only been confirmed in the North Atlantic, however the stranding of a pregnant female with a calf on the coast of Port Elizabeth, South Africa confirmed the existence of a breeding population in the southern hemisphere as well (Ross 1969).

North Atlantic

In the North Atlantic, the distribution of True’s beaked whales reaches from eastern North America (Nova Scotia to Florida) to Bermuda and in Europe, from the British Isles to the Canary Islands, the Bay of Biscay, and the Azores.

Habitat

The species is mostly described from strandings and little knowledge is available about their habitat as they are seldom observed in the wild. When observed they are, however, found offshore in the deep waters beyond the continental shelf.

Did you know?

The species received its common name from Frederick W. True, a curator at the Smithsonian Institution, who described the species from a single specimen that stranded on a beach in North Carolina.

Movements and Migration

Breaching Trues beaked whales (Aguilar de Soto et al. 2017).

No information is available about True’s beaked whales’ migration pattern.

Abundance and Trends

There are no estimates of abundance for this species, neither globally nor regionally. The species is, however, not considered rare in the North Atlantic.

Human impacts

There is little specific information on the threats of this species, but it is generally thought to be the same as in other beaked whales (Reeves et al. 2003).  See general threats on beaked whales

Human removals: Hunt / By-catch

No direct catches of the species have been reported. Entanglement in fishing gear, especially gillnets in deep water (e.g., for billfish and tuna), is probably the most significant threat (Taylor et al. 2008).

Noise/disturbance

See the general introduction to beaked whales

Strandings

For the North Atlantic, most strandings have occurred in the southern temperate water. A 3.7 m long subadult male True’s beaked whale with unerupted teeth stranded (dead) in the Azores in 2004, (Silva et al. 2014). An adult male stranded on the island of Lanzarote (Vonk and Martin 1988) in the Canary Islands. Both animals were identified as True’s beaked whales by their general morphology. Strandings of True’s beaked whales have also been reported off the British Isles, most recently with two strandings on the Irish Coast in 2018 (BBC 2018).

Climate change

Climate change will have different effects on cetacean species in accordance with their distribution and habitat. True’s beaked whales depend on deep-sea cephalopod prey species, and any impact on this specific group of species, either directly, e.g. shift in distribution, or indirectly, e.g. habitat alteration, will have consequences for the True’s beaked whales.

Conservation and Management

For more information see the section on Conservation and Management under general information.

Did you know?

Frederick W. True gave the True’s beaked whale the species name mirus which is Latin for wonderful or amazing, which gave this species the alternative common name wonderful beaked whale.

General introduction

Aguilar de Soto, N., Martin, V., Silva, M., Edler, R., Reyes, C., Carrillo, M., … and Carroll E. (2017). True’s beaked whale (Mesoplodon mirus) in Macaronesia. Peer Journal, 5, e3059. https://doi.org/10.7717/peerj.3059

Barlow, J. (1999). Trackline detection probability for long-diving whales. In J. L. Laake, D. G. Robertson, Steven C. Amstrup (eds.), Marine Mammal Survey and Assessment Methods, 209–221. Rotterdam: Balkema.

Carroll, E. L., Reyes, C., Gaggiotti, O. E., Olsen, M. T., Maaholm, D. J. and Rosso, M. (2016). Pilot study to assess the utility of ddRAD sequencing in identifying species-specific and shared SNPs among Blainville’s (Mesoplodon densirostris) and Cuvier’s (Ziphius cavirostris) beaked whales. In Report SC/66b/DNA/03 Presented to the Scientific Committee. London: International Whaling Commission.

Dalebout, M., Baker, C. S., Mead, J. G., Cockcroft, V. G. and Yamada, T. K. (2004). A comprehensive and validated molecular taxonomy of beaked whales, family Ziphiidae. Journal of Heredity, 95(6), 459-473. https://doi.org/10.1093/jhered/esh054

Dalebout, M. L., Robertson, K. M., Frantzis, A., Engelhaupt, D., Mignucci-Giannoni, A. A., Rosario-Delestre, R. J. and Baker, C. S. (2005). Worldwide structure of mtDNA diversity among Cuvier’s beaked whales (Ziphius cavirostris): Implications for threatened populations. Molecular Ecology, 14, 3353-3371. https://doi.org/10.1111/j.1365-294X.2005.02676.x

Dalebout, M., Ruzzante, D. E., Whitehead, H. and Øien, N.I. (2006). Nuclear and mitochondrial markers reveal distinctiveness of a small population of bottlenose whales (Hyperoodon ampullatus) in the western North Atlantic. Molecular Ecology, 15, 3115-3129. https://doi.org/10.1111/j.1365-294X.2006.03004.x

Dalebout, M., Steel, D. and Baker, C. S. (2008). Phylogeny of the beaked whale genus Mesoplodon (Ziphiidae: Cetacea) revealed by nuclear introns: Implications for the evolution of male tusks. Systematic Biology, 57(6), 857-875. https://doi.org/10.1080/10635150802559257

DeRuiter, S. L., Southall, B. L., Calambokidis, J., Zimmer, W. M. X., Sadykova, D. and Falcone, E. A., (2013). First direct measurements of behavioral responses by Cuvier’s beaked whales to mid-frequency active sonar. Biology Letters, 9. https://doi.org/10.1098/rsbl.2013.0223

Ellis, R. and Mead, J.G. (2017). Beaked Whales: A Complete Guide to Their Biology and Conservation. Baltimore, US: Johns Hopkins University Press. https://doi.org/10.1353/book.52552

Fernandez, A., Edwards, J. F., Rodríguez, F., Espinosa de Los Monteros, A., Herráez, P., Castro, … and Arbelo, M. (2005) “Gas and fat embolic syndrome” involving a mass stranding of beaked whales (Family Ziphiidae) exposed to anthropogenic sonar signals. Veterinary Pathology, 42, 446-457. https://doi.org/10.1354/vp.42-4-446

Fossi, M. C., Panti, C., Baini, M. and Lavers, J. L. (2018). A review of plastic-associated pressures: Cetaceans of the Mediterranean Sea and eastern Australian Shearwaters as case studies. Frontiers in Marine Science, 5, 173. https://doi.org/10.3389/fmars.2018.00173

Gomerčić, H., Gomerčić, M. D., Gomerčić, T., Lucić, H., Dalebout, M., Galov, T., … and Huber, D. (2006). Biological aspects of Cuvier’s beaked whale (Ziphius cavirostris) recorded in the Croatian part of the Adriatic Sea. European Journal of Wildlife Research, 52, 182–187. https://doi.org/10.1007/s10344-006-0032-8

Hemshaw, M. D., LeDuc, R. G. and Chivers, S. J. (1997). Identifying beaked whales (family Ziphiidae) using mtDNA sequences. Marine Mammal Science, 13(3), 487-495. https://doi.org/10.1111/j.1748-7692.1997.tb00656.x

Heyning, J. E. (1984). Functional morphology involved in intraspecific fighting of the beaked whale, Mesoplodon carlhubbsi. Canadian Journal of Zoology, 62, 1645–1654. https://doi.org/10.1139/z84-239

Heyning, J. E. (1989). Cuvier’s beaked whale Ziphius cavirostris G. Cuvier, 1823. In S. H. Ridgway and R. J. Harrison (eds.), Handbook of Marine Mammals, volume 4: River dolphins and the larger toothed whales, 289-308. London, UK:Academic Press.

Heyning, J. E. and Mead, J. G. (1996). Suction Feeding in Beaked Whales: Morphological and Observational Evidence. Natural History Museum of Los Angeles County, 464, 1-12.

Hammond, P. S., Lacey, C., Gilles, A., Viquerat, S., Börjesson, P., Herr, … Øien, N. (2017). Estimates of cetacean abundance in European Atlantic waters in summer 2016 from the SCANS-III aerial and shipboard surveys. University of St. Andrews. Available at: St.Andrews University

Hooker, S. K., Aguilar de Soto, N., Baird, R.W., Carroll, E. L., Claridge, D., Feyrer, L., …, Whitehead H. (2019). Future directions in research on beaked whales. Frontiers in Marine Science, 5(514). https://doi.org/10.3389/fmars.2018.00514

Jepson, P. D., Arebelo, M., Deaville, R., Patterson, I. A. P., Castro, P., Baker, … and Fernandez, A. (2003). Gas-bubble lesions in stranded cetaceans. Nature, 425, 575-576. https://doi.org/10.1038/425575a

Johnson M., Madsen P.T., Zimmer W.M.X., Aguilar de Soto N. and Tyack P.L. (2004). Beaked whales echolocate on prey. Proceedings of the Royal Society London B, 271, 383-386. https://doi.org/10.1098/rsbl.2004.0208

Laist, D. W. (1997). Impacts of marine debris: entanglement of marine life in marine debris including a comprehensive list of species with entanglement and ingestion records. In. J. M Coe and D. B. Rogers (eds.), Marine debris: sources, impacts and solutions, 99–139. New York, NY: Springer. https://doi.org/10.1007/978-1-4613-8486-1_10

MacLeod, C. D., Santos, M. B. and Pierce, G. J. (2003). Review of data on diets of beaked whales: evidence of niche separation and geographic segregation. Journal of Marine Biology, 83, 651-665. https://doi.org/10.1017/S0025315403007616h

Macleod, C. D., Perrin, W. F., Pitman, R. L., Barlow, J., Balance, L., D’amico, A., Gerrodette, T., Joyce, G., Mullin, K. D., Palka, D. L. and Waring, G. T. (2006). Known and inferred distributions of beaked whale species (Ziphiidae: Cetacea). Journal of Cetacean Research and Management, 7(3), 271-286. https://archive.iwc.int/pages/search.php?search=%21collection15&k=

MacLeod, C.D., (2018). Beaked whales, overview. In B. Würsig, J. G. M. Thewissen and K. M. Kovacs (eds.), Encyclopedia of Marine Mammals (third edition), 80-83. London, UK: Elsevier. https://doi.org/10.1016/B978-0-12-804327-1.00062-5

Madsen, P. T., Aguilar de Soto, A., Tyack, P. L. and Johnson, M. (2015) Beaked whales. Current Biology 24(16), 728-730. https://doi.org/10.1016/j.cub.2014.06.041

Malakoff, D. (2002). Suit ties whale deaths to research cruise. Science, 298(5594), 722-723. https://doi.org/10.1126/science.298.5594.722

Morin P.A., Baker C.S., Brewer R.S., Burdin A.M., Dalebout M.L., Dines J.P., … and Wade P.R. (2017). Genetic structure of the beaked whale genus Berardius in the North Pacific, with genetic evidence for a new species. Marine Mammal Science, 33(1), 96-111. https://doi.org/10.1111/mms.12345

Pitman, R. (2018). Mesoplodon Beaked Whales. In B. Würsig, J. G. M. Thewissen and K. M. Kovacs. Encyclopedia of Marine Mammals (third edition), 595 – 601. London, UK: Elsevier. https://doi.org/10.1016/B978-0-12-804327-1.00172-2

Puig-Lozano R., Bernaldo de Quirós Y., Díaz-Delgado J., García-Álvarez N., Sierra E., De la Fuente J., Sacchini S., … and Arbelo M. (2018). Retrospective study of foreign body-associated pathology in stranded cetaceans, Canary Islands (2000-2015). Environmental Pollution, 243, 519-527. https://doi.org/10.1016/j.envpol.2018.09.012

Rogan, E., Cañadas, A., Macleod, K., Begoña Santos, M., Mikkelsen, B., Uriarte, A., … and Hammond, P. S. (2017). Distribution, abundance and habitat use of deep diving cetaceans in the North-East Atlantic. Deep Sea Research Part II: Topical Studies in Oceanography, 141, 8-19. https://doi.org/10.1016/j.dsr2.2017.03.015

Rogan, E., Breen, P., Mackey, M., Cañadas, A., Scheidat, M., Geelhoed, S. C. V. and Jessopp, M. (2018). Aerial Surveys of Cetaceans and Seabirds in Irish waters: Occurrence, distribution and abundance in 2015-2017. https://secure.dccae.gov.ie/downloads/SDCU_DOWNLOAD/ObSERVE_Aerial_Report.pdf

Secchi, E. R. and Zarzur, S. (1999). Plastic debris ingested by a Blainville’s beaked whale, Mesoplodon densirostris, washed ashore in Brazil. Aquatic Mammals, 25(1), 21-24. https://www.researchgate.net/publication/263203190_Plastic_debris_ingested_by_a_Blainville%27s_beaked_whale_Mesoplodon_densirostris_washed_ashore_in_Brazil

Thompson, K. F., Patel, S., Baker, C. S., Constantine, R. and Millar, C. D. (2016). Bucking the trend: genetic analysis reveals high diversity, large population size and low differentiation in a deep ocean cetacean. Heredity, 116, 277-285. https://doi.org/10.1038/hdy.2015.99

Cuvier’s beaked whale

Aguilar de Soto, N., Gkikopoulou, K. C., Hooker, S., Isojunno, S., Johnson, M., Miller, P., … and Thomas, L. (2016). From physiology to policy: a review of physiological noise effects on marine fauna with implications for mitigation. Proceedings of Meetings of Acoustics, 27, 040008. https://doi.org/10.1121/2.0000299

Baird, R. W. (2018). Cuvier’s Beaked Whale Ziphius cavirostris. In B. Würsig, J. G. M. Thewissen and K. M. Kovacs (eds.), Encyclopedia of Marine Mammals (third edition), 234-237. London, UK: Elsevier. https://doi.org/10.1016/B978-0-12-804327-1.00100-X

Bachara, W. and Øien, N. (2017). Stranding records of Cuvier’s beaked whales (Ziphius cavirostris) in Norway. Unpublished report to Cetal Fauna. Report WB2017/2. 2 pp. https://www.researchgate.net/publication/329220486_Bachara_W_and_Oien_N_2017_Stranding_records_of_Cuvier%27s_beaked_whales_Ziphius_cavirostris_in_Norway_Unpublished_report_to_Cetal_Fauna_Report_WB20172_2_pp

Bernaldo de Quirós, Y., Fernandez, A., Baird, R. W., Brownell, R. L., Aguilar de Soto, N., Allen, D., … and Schorr, G. (2019). Advances in research on the impacts of anti-submarine sonar on beaked whales. Proceedings of the Royal Society B, 286, 20182533. https://doi.org/10.1098/rspb.2018.2533

Brownlow, A., Davison, N. and ten Doeschate, M. (2018).  Annual Report 2018 1 January to 31 December 2018 for Marine Scotland, SRUC Wildlife Unit Drummondhill Inverness. Scotland: Scottish Government. https://www.strandings.org/smass/publications/reports/SMASS_Annual_Report_2018.pdf

Cañadas, A. (2012). Ziphius cavirostris (Mediterranean). The IUCN Red List of Threatened Species 2012: e.T23211A2785108. www.iucnredlist.org

Coomber, F., Moulin, A., Tepsich, P. and Rosso, M. (2016). Sexing free-ranging adult Cuvier’s beaked whales (Ziphius cavirostris) using natural marking thresholds and pigmentation patterns, Journal of Mammalogy, 97(3), 879-890. https://doi.org/10.1093/jmammal/gyw033

D’Amico, A., Gisner, R. C., Ketten, D. R., Hammock, J. A., Johnson, C., Tyack P. L. and Mead J. G. (2009). Beaked whale strandings and naval exercises. Aquatic Mammals, 55(4), 452–472. https://doi.org/10.1578/AM.35.4.2009.452

Dalebout, M. L., Robertson, K. M., Frantzis, A., Engelhaupt, D., Mignucci-Giannoni, A. A., Rosario-Delestre, R. J. and Baker, C. S. (2005). Worldwide structure of mtDNA diversity among Cuvier’s beaked whales (Ziphius cavirostris): Implications for threatened populations. Molecular Ecology, 14, 3353-3371. https://doi.org/10.1111/j.1365-294X.2005.02676.x

Dolman, S., Pinn, E., Reid, R., Barley, J., Deaville, R., Jepson, P. and Simmonds, M. (2010). A note on the unprecedented strandings of 56 deep-diving whales along the UK and Irish coast. Marine Biodiversity Records, 3. https://doi.org/10.1017/S175526720999114X

Frantzis, A. (1998). Does acoustic testing strand whales? Nature London, 5(392), 29. https://doi.org/10.1038/32068

Heyning, J. E. (1989). Cuvier’s beaked whale Ziphius cavirostris G. Cuvier, 1823. In Ridgway, S. H. and Harrison, R. J. (eds.), Handbook of Marine Mammals, volume 4: River dolphins and the larger toothed whales, 289-308. London, UK: Academic Press

Heyning, J. E. and Mead, J. G. (1996). Suction Feeding in Beaked Whales: Morphological and Observational Evidence. Natural History Museum of Los Angeles County, 464, 1-12.

Hoelzel A.R. (1998). Genetic structure of cetacean populations in sympatry, parapatry, and mixed assemblages: Implications for conservation policy. The American Genetic Association, 89, 451-458. https://doi.org/10.1093/jhered/89.5.451

Jepson, P. D., Arebelo, M., Deaville, R., Patterson, I. A. P., Castro, P., Baker, J. R., … and Fernandez, A. (2003). Gas-bubble lesions in stranded cetaceans. Nature, 425, 575-576. https://doi.org/10.1038/425575a

Ketten, D.R. (2014). Sonars and strandings: are beaked whales the aquatic acoustic canary? Acoustics Today Summer, 46-56. Available at: Acoustics today.

MacLeod, C. D., Santos, M. B. and Pierce, G. J. (2003) Review of data on diets of beaked whales: evidence of niche separation and geographic segregation. Journal of Marine Biology, 83, 651-665. https://doi.org/10.1017/S0025315403007616h

McSweeney, D. J., Baird R. W. and Mahaffy S. D. (2007). Site fidelity, associations, and movements of Cuvier’s (Ziphius cavirostris) and Blainville’s (Mesoplodon densirostris) beaked whales off the island of Hawaii. Marine Mammal Science, 23(3), 666-687. https://doi.org/10.1111/j.1748-7692.2007.00135.x

New L. F., Moretti D. J., Hooker S. K., Costa D. P and Simmons S. E. (2013). Using energetic models to investigate the survival and reproduction of beaked whales (family Ziphiidae). PLoS ONE, 8(7), e68725. https://doi.org/10.1371/journal.pone.0068725

Rogan, E., Cañadas, A., Macleod, K., Begoña Santos, M., Mikkelsen, B., Uriarte, A., … and Hammond, P. S. (2017). Distribution, abundance and habitat use of deep diving cetaceans in the North-East Atlantic. Deep Sea Research Part II: Topical Studies in Oceanography, 141, 8-19. https://doi.org/10.1016/j.dsr2.2017.03.015

Ross, G. J. B. (2006). Review of the conservation status of Australia’s smaller whales and dolphins Australian Government. Available at: Department of the Environment and Heritage

Schorr, G. S., Falcone, E. A., Moretti, D. J. and Andrews, R. D. (2014). First Long-Term Behavioral Records from Cuvier’s Beaked Whales (Ziphius cavirostris) Reveal Record-Breaking Dives. PLoS ONE, 9(3), e92633. https://doi.org/10.1371/journal.pone.0092633

Taylor, B. L., Baird, R., Barlow, J., Dawson, S. M., Ford, J., Mead, J. G., … and Pitman, R. L. (2008). Ziphius cavirostris. The IUCN Red List of Threatened Species 2008: e.T23211A9429826. https://doi.org/10.2305/IUCN.UK.2008.RLTS.T23211A9429826.en

Tyack, P. L., Johnson, M., Aguilar Soto, N., Sturlese, A. and Madsen, P. T. (2006). Extreme diving of beaked whales. The Journal of Experimental Biology, 209, 4238-4253. https://doi.org/10.1242/jeb.02505

Blainville’s beaked whale

Claridge, D.E. (2013).Population Ecology of Blainville’s beaked whales (Mesoplodon densirostris). Ph.D. thesis in Biology. University of St Andrews, Scotland. Available at: St.Andrews.

Dunn, B. P. (2015). Insights into Blainville’s Beaked Whale (Mesoplodon densirostris) Communication. Ph.D. thesis, University of St Andrews, Scotland. Available at: St. Andrews.

Ellis, R. and Mead, J. G. (2017). Beaked Whales: A complete guide to their biology and conservation. 194 pp. US:  James Hopkins University Press

Hooker S.K., Aguilar de Soto N., Baird R.W., Carroll E.L., Claridge D., Feyrer L., …  and Whitehead H. (2019). Future directions in research on beaked whales. Frontiers in Marine Science, 5(514). https://doi.org/10.3389/fmars.2018.00514

Jefferson, T., Webber, M. and Pitman, R. (2008). Marine Mammals of the Word: A Comprehensive Guide to Their Identification. London, England: Elsevier Publications. https://doi.org/10.1016/B978-0-12-804327-1.00172-2

Jepson, P. D., Arebelo, M., Deaville, R., Patterson, I. A. P., Castro, P., Baker, … and Fernandez, A. (2003). Gas-bubble lesions in stranded cetaceans. Nature, 425, 575-576. https://doi.org/10.1038/425575a

Pitman, R. (2018). Mesoplodon Beaked Whales. In B. Würsig, J. G. M. Thewissen and K. M. Kovacs (eds.), Encyclopedia of Marine Mammals (third edition), 595 – 601. London, UK: Elsevier. https://doi.org/10.1016/B978-0-12-804327-1.00172-2