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Overview

Brief Summary

Worldwide, there are many species of beaked whales, all looking very much alike. There is hardly anything known about these mysterious whales, except that they are very shy. In the North Sea, Sowerby's beaked whales are seen most often. They are even found regularly in the extreme northern part of the North Sea, but are rarely observed in the south. In general, Sowerby's are found mostly in the northern Atlantic Ocean and the Mediterranean Sea.
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Description

"Most stranded Sowerby's beaked whales have been found on the coast of the British Isles, and the North Sea may be the center of the species' distribution. We know very little about this whale, including what it eats and details of its growth, reproduction, and social organization. Adults are slightly more than 5 m in length and have bluish-gray or slate gray backs; calves are reported to be about 2.4 m long at birth. Stranded whales have been heard making cow-like vocalizations. At sea, this whale can be identified by its long snout. Adult males have distinctive, tall teeth that slant out and up from the sides of the jaw about a third of the way back from the front end of the mouth."

Adaptation: The odd, single-toothed skull of a Beaked whale, Mesoplodon, is an example of the strange skull shapes that have evolved among cetaceans.

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Mammal Species of the World
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Comprehensive Description

Description

 Mesoplodon bidens is a toothed whale and can be recognised as such by the single blowhole and the presence of teeth (rather than baleen). It is a member of the beaked whale family with the characteristic V-shaped crease on the throat and the short dorsal fin set relatively far back. Sowerby's beaked whale is a small beaked whale that can reach up to 5.5 m in length. The lower jaw has a single pair of teeth (exposed only in adult males). The forehead rises at a shallow angle and has a slight bump. It has a distinct beak and the mouthline is curved down at rear. Sowerby's beaked whale has a charcoal grey dorsal and lateral colouration with a lighter belly. Adults may also have light grey spots on the body and are often covered with scratches and scars.Sowerby's beaked whale may be confused with True's beaked whale Mesoplodon mirus but can be recognised by a slight bump on the forehead and a slightly longer beak. Sowerby's beaked whales are usually found either alone or in groups of up to 10 individuals. Little is known about their behaviour although tail-slapping has been recorded. Dives may last up to 15 minutes long (Kinze, 2002).
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Distribution

North Atlantic (Eastern and Western), including North sea; considered rare in Canadian waters
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Sowerby's beaked whales are found in temperate to sub arctic waters in the eastern and western North Atlantic. They are found around the British Isles and are known to occur from Newfoundland to Massachusetts. Sowerby's beaked whales occur as far north as Labrador in the west and in the Norwegian Sea in the east, southern limit is thought to be somewhere between 33ºN and 41ºN.

Biogeographic Regions: nearctic (Native ); palearctic (Native ); atlantic ocean (Native )

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Range Description

Sowerby's beaked whales are known almost exclusively from the colder waters of the North Atlantic, from at least Massachusetts, USA to Labrador, Canada in the west, and from Iceland to Norway in the east (Mead 1989; MacLeod et al. 2006). This is the most northerly distributed of the Atlantic species of Mesoplodon, with most records north of 30°N. There are a number of strandings or sightings considered to be extralimital in the Mediterranean Sea, and from the Gulf of Mexico side of Florida.
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occurs (regularly, as a native taxon) in multiple nations

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Global Range: Mainly in cooler offshore waters of North Atlantic and Baltic Sea; a report for the coast of Italy may be valid; more common in European waters than in American waters, where single strandings have been recorded for near Nantucket, Massachusetts, and in eastern Canada (Mead and Brownell, in Wilson and Reeder 1993). Range may be centered in the North Sea. See Bonde and O'Shea (1989) for information on a 1984 stranding in Florida (regarded as a stray). Poorly known; as of late 1980s, less than 40 published stranding records, 11 in North America (Bonde and O'Shea 1989; 1990, Can. Field-Nat. 104:414-420). See Lien and Barry (1990) for information on status in Canada. Hooker and Baird (1999) described recent observations of groups of individuals in the Gully, Nova Scotia.

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National Distribution

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Physical Description

Morphology

Mesoplodon bidens is bluish grey to slate grey in color, with a lighter underside, grey and white spots may be present on the body with limited scaring. Mesoplodon bidens have a long slender beak that contains a pair of teeth midway up the lower jaw. They have a long think body, long flippers for the Mesoplodon family, and no notch in the fluke. The dorsal fin is quite small with a rounded tip and may appear falcate. Young M. bidens have a light blusih grey to white underside, more prominant than in adults.

Range mass: 1000 to 1300 kg.

Range length: 5 to 5.5 m.

Sexual Dimorphism: male larger

Other Physical Features: endothermic ; bilateral symmetry

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Size

Length: 4900 cm

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Size in North America

Length:
Range: 5.5 m males; 5.1 m females

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Ecology

Habitat

offshore
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also in shelf areas
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Sowerby's beaked whales are found in cool to warm temperate offshore waters of the North Atlantic Ocean. They are usually observed in open water and most often seen in areas were depths range from 198 to 1524 m.

Range depth: 198 to 1524 m.

Habitat Regions: temperate ; saltwater or marine

Aquatic Biomes: pelagic

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Habitat and Ecology

Habitat and Ecology
As with other members of the genus, these whales occur almost exclusively in deep waters past the continental shelf edge. Although it is one of the most commonly stranded Mesoplodon species, there have been few sightings at sea, and it is poorly known. De Buffrénil (1995) mentioned that two sightings were north of Scotland and west of the Orkney Islands, in waters several 100 m deep. Hooker and Baird (1999) observed groups of Sowerby's Beaked Whales in the Gully, a submarine canyon off eastern Canada, on four occasions. Sightings were in water depths of between 550 m and 1,500 m.

Ostrom et al. (1993) evaluated the diet of Sowerby's beaked whales, based on isotopic comparisons among northwestern Atlantic cetaceans. They feed on squid and fish, including Atlantic cod (Gadus morhua).

Systems
  • Marine
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Habitat Type: Marine

Comments: Deeper areas of the open ocean.

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Depth range based on 34 specimens in 1 taxon.
Water temperature and chemistry ranges based on 26 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 9.488 - 19.052
  Nitrate (umol/L): 1.393 - 9.648
  Salinity (PPS): 33.265 - 35.293
  Oxygen (ml/l): 5.437 - 6.344
  Phosphate (umol/l): 0.248 - 0.683
  Silicate (umol/l): 1.541 - 3.866

Graphical representation

Temperature range (°C): 9.488 - 19.052

Nitrate (umol/L): 1.393 - 9.648

Salinity (PPS): 33.265 - 35.293

Oxygen (ml/l): 5.437 - 6.344

Phosphate (umol/l): 0.248 - 0.683

Silicate (umol/l): 1.541 - 3.866
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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 Sowerby's beaked whale is an oceanic and coastal species that may be seen at the surface but little is known on what depth they may dive to.
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Migration

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Trophic Strategy

The diet of Sowerby's beaked whales consists mostly of squid, octopus, and fish. A necropsy of one individual showed stomach contents that included bottom-dwelling and deep water fish.

Animal Foods: fish; mollusks

Primary Diet: carnivore (Piscivore , Molluscivore )

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Comments: Diet probably includes small offshore squid (Ostrom et al., 1993, Can. J. Zool. 71:858-861) and deepwater fishes.

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Associations

Little is known about the role of Sowerby's beaked whales in the northern Atlantic ecosystem. They are undoubtedly predators of marine organisms.

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There is no information about predation on Sowerby's beaked whales. Once they reach their adult size it is likely that they are protected from much predation. Killer whales and large sharks may target Sowerby's beaked whales.

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General Ecology

Not highly gregarious; found alone or in groups of up to 8-10 individuals (Hooker and Baird 1999).

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Life History and Behavior

Behavior

Diet

squid and small fish
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A young animal, that was kept in a dolphinarium for a few hours, was recorded using high frequency sound pulses to echolocate.

Communication Channels: acoustic

Perception Channels: visual ; tactile ; acoustic ; echolocation ; chemical

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Cyclicity

Comments: Active day/night.

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Life Expectancy

The is no data on the lifespan in M. bidens.

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Reproduction

Nothing is known about the mating systems of M. bidens.

Little in known about general reproductive behavior of M. bidens. Mating is thought to occur in late winter, with births late in spring and gestation lasting about 12 months. Young are about 2.4 to 2.7 meters in length and weigh about 185 kg.

Breeding interval: Breeding interval is not known for Sowerby's beaked whales.

Breeding season: Mating is thought to occur in late winter.

Average number of offspring: 1.

Average gestation period: 12 months.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous

Sowerby's beaked whale females provide milk for their young and protect them. There is no other available information on parental investment.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

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Limited data suggest that mating and birth ocuur in late winter and spring. Gestation lasts about 1 year.

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Conservation

Conservation Status

There is very little data on Sowerby's beaked whales. As a result there is little information on population sizes, current or historic, to determine conservation status. This species is rarely seen in the open ocean, most records are from strandings.

US Federal List: no special status

CITES: appendix ii

State of Michigan List: no special status

IUCN Red List of Threatened Species: data deficient

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IUCN Red List Assessment


Red List Category
DD
Data Deficient

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L.

Reviewer/s
Hammond, P.S. & Perrin, W.F. (Cetacean Red List Authority)

Contributor/s

Justification
There is no information on global abundance or trends in abundance for this species. It is not believed to be uncommon but it is potentially vulnerable to low-level threats and a 30% global reduction over three generations cannot be ruled out (criterion A).

History
  • 1996
    Data Deficient
  • 1994
    Insufficiently Known
    (Groombridge 1994)
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National NatureServe Conservation Status

Canada

Rounded National Status Rank: NNR - Unranked

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NatureServe Conservation Status

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Occurs mainly in cooler offshore waters of North Atlantic and Baltic Sea; more common in European waters than in American waters, where single strandings have been recorded for near Nantucket, Massachusetts, and in eastern Canada; poorly known--as of late 1980s, less than 40 published stranding records, 11 in North America.

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Population

Population
Very little is known of the population biology of this species. It is one of the most commonly seen mesoplodonts in some parts of its range.

Population Trend
Unknown
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Threats

Major Threats
There is little specific information on the status or threats to whales of this species (Reeves et al. 2003). However, some are known to have been 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 for 1989-1998 observed bycatch in pelagic drift gillnets along the US East Coast amounted to 24 Sowerby's beaked whales. These were caught exclusively in the area from Georges Canyon to Hydrographers Canyon, along the continental shelf break and continental slope during July-October. This fishery has now been closed.

This species, like other beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration (Cox et al. 2006).

Evidence from stranded individuals of several similar species indicates that they have swallowed discarded plastic items, which may eventually lead to death (e.g. Scott et al. 2001); this species may also be at risk.

Predicted impacts of global climate change on the marine environment may affect this species of whale, although the nature of impacts is unclear (Learmonth et al. 2006).
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Management

Conservation Actions

Conservation Actions
The species is listed in Appendix II of CITES. Research is needed to determine the impacts of potential threatening processes on this species.
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Relevance to Humans and Ecosystems

Benefits

Sowerby's beaked whales are occasionally caught in fishing gear, damaging nets in the process. Arguably this is more traumatic for the whales than fishing crews.

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Sowerby's beaked whales were once infrequently harvested by Norwegian whalers. They are no longer hunted actively.

Positive Impacts: food

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Risks

IUCN Red List Category

Data Deficient (DD)
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Wikipedia

Sowerby's beaked whale

Sowerby's beaked whale!<-- This template has to be "warmed up" before it can be used, for some reason -->

Sowerby's beaked whale (Mesoplodon bidens), also known as the North Atlantic/North Sea beaked whale, was the first beaked whale to be described. Its name, bidens, derives from the two teeth present in the jaw, now known to be a very common feature among the genus.

Contents

Physical description

Profile of an adult female

Sowerby's beaked whale has a typical body shape for the genus, and is mainly distinguished by the male's dual teeth positioned far back in the mouth. The whale's beak is moderately long, and the melon is slightly convex. The colouration pattern is a grey with light countershading on the bottom, and frequently has cookie cutter shark bites and scars from teeth (in males). The whale reaches 5 metres (16 ft) in females and 5.5 metres (18 ft) in males, with a weight of 1000-1300 kilograms (2200-2900 lb). The gestation period lasts for 12 months and the young are born at a length of 2.4 to 2.7 metres (8 to 9 ft) with a weight of around 185 kilograms (400 lb).

Population and distribution

Sowerby's beaked whale ranges from Nantucket to Labrador in the Western Atlantic and from Madeira to the Norwegian Sea in the Eastern Atlantic. They typically range in waters 200 to 1,500 metres (650 to 5,000 ft) deep. No population estimates have been made.

On January 10, 2009, a female Sowerby's beaked whale was found at the port of Fethiye on the Aegean coast of Turkey, far away from her natural habitat. The whale was successfully saved and released back to the open sea.[1] In August of the same year, a Sowerby's beaked whale was found on the beach at Blakeney Point in Norfolk, England by holiday makers including a Mr. A. Davies and associates. The tide was rapidly receding, and being watched by a Seal Tour Boat, they managed to return the whale to the sea using a stretcher used for injured seals. All worked extremely hard, and their work paid off as the whale was returned safely out to sea.[citation needed]

Behaviour

Sowerby’s beaked whales are reclusive creatures that stay away from ships and are rarely sighted. The whales are occasionally in groups of 8 to 10 individuals (males, females, and calves) and have been known to strand in groups as well. They are believed to primarily feed on squid and molluscs, but cod has also been found in their stomachs. They have been known to dive down at times approaching 30 minutes.

Conservation

Skull of Sowerby's beaked whale.

The species has been hunted infrequently by Norwegians, but such practices have long since been abandoned. There are some deaths due to entanglement in fishing gear, but it is unlikely to be very damaging to the species.

Notes

  1. ^ Hürriyet daily newspaper: "Balinaymış". Published on January 12, 2009. Retrieved on January 12, 2009.

References

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