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Bryde's Whales
Size comparison against an average human
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Eutheria
Order: Cetacea
Suborder: Mysticeti
Family: Balaenoptiidae
Genus: Balaenoptera
Species: brydei
edeni
omurai

Binomial name
Balaenoptera brydei
Olsen, 1913
Balaenoptera edeni
Anderson, 1879
Bryde's Whale range

Bryde's whales are baleen whales, one of the "great whales" or rorquals. They prefer tropical and temperate waters over the polar seas that other whales in their family frequent. They are largely coastal rather than pelagic. Bryde's Whales are very similar in appearance to Sei Whales and almost as large.

"Bryde" is pronounced /ˈbruːdə/ ("brooda"), and "Bryde's whale" is sometimes misheard as "brutus whale". The name comes from the Norwegian consul to South Africa, Johan Bryde, who helped set up the first whaling station in Durban, South Africa in 1908.

They inhabit tropical and subtropical waters worldwide.

Bryde's whales are considered medium-sized for balaenopterids, dark gray in color with a white underbelly.

Contents

Taxonomy

The taxonomy is poorly characterized. Three genetically distinct, candidate species/subspecies/morphologies, Bryde's whale B. brydei, Bryde's/Eden's whale B. edeni[2], and Omura's whale B. omurai,[3] differentiate by geographic distribution, inshore/offshore preferences, and size. For at least two of the species, the scientific name B. edeni is common. Omura's whale, a pygmy, is only recently described and reaches only 37.5–39 feet (11.4–11.9 m).[4]

They were not described until 1878, from a stranded specimen on the coast of Burma, which was given the name Balaenoptera edeni. In 1913 whales off the coast of South Africa were described as Balaenoptera brydei, the name being given to honour Johan Bryde, Norwegian consul and pioneer of the South African whaling industry.

By the 1950s, scientists grouped them in a single species, B. edeni, retaining Bryde's Whale as the common name.

Description

They can reach lengths of 40–55 feet (12–17 m) and weigh up to 90,000 pounds (41,000 kg). Males are usually slightly smaller than females.

Anatomy

Photo of Bryde's whale at surface

The Bryde’s whale is a baleen whale (rorqual.) It has twin blowholes with a low splashguard to the front. Like other rorquals it has no teeth but has two rows of baleen plates.

The head of Bryde's whales makes up about 25% of the body, with relatively large eyes. Each side of the mouth features 250-410 coarse gray baleen plates up to 40 centimetres (16 in) long. 40-70 ventral pleats are located on the animal's underside. Omura's whales have 180-210 baleen plates on each side and 80-90 ventral pleats. Bryde's whale is unique amongst rorquals in that it has three longitudinal ridges on its rostrum, from the tip of the snout back to the blowhole. Sei whales, with which they are often mistaken, like other rorquals, have a single median ridge. Omura's whales have no ridges.[4]

These whales have an erect, curved, pointed, "falcate" dorsal fin located far down its back and broad flukes. The dorsal fin is visible at the surface. The broad, centrally notched tail flukes never break the surface. The flippers are small and slender.[4]

Color varies: the back is generally dark grey or blue to black. The ventral area is a lighter cream, shading to greyish purple on the belly. Some have a number of whitish-grey spots, which may be scars from parasites or shark attacks. Omuras have asymmetrical head coloring, similar to fin whales.[4]

Behavior

Their blow is columnar or bushy, about 10–13 feet (3.0–4.0 m) high. Sometimes they blow or exhale while under water. Bryde's whales display seemingly erratic behavior compared to other baleens, because they surface at irregular intervals and can change directions for unknown reasons.[4]

They usually appear individually or in pairs, and occasionally in loose aggregations of up to twenty animals around feeding areas.[4]

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Breathing

They regularly dive for about 5-15 minutes (max of 20 minutes) after 4-7 blows. Bryde's whales are capable of reaching depths up to 1,000 feet (300 m). When submerging, these whales do not display their flukes. Bryde's whales commonly swim at 1–4 miles per hour (1.6–6.4 km/h), but can reach 12–15 miles per hour (19–24 km/h).[4]

They sometimes generate short (0.4 seconds) powerful, low frequency vocalizations that resemble a human moan.[4]

Diet

These whales opportunistically feed on plankton (e.g., krill and copepods), and crustaceans (e.g. pelagic red crabs, shrimp) as well as schooling fish (e.g., anchovy, herring, sardine, mackerel, and pilchards). Bryde's whales use several feeding methods, including skimming the surface, lunging, and bubble nets.[4]

Reproduction and nurturing

Bryde’s whales breed in alternate years, apparently in any season, with an autumnal peak. Their gestation period is estimated at 12 months. Calves are about 4 metres (13 ft) long at birth and weigh 1,000 kilograms (2,200 lb). They become sexually mature at 8-13 years of age. At birth, the single calf is about 11 feet (3.4 m). The mother nurses for 6-12 months.[4]

Range and habitat

Bryde's whales prefer highly productive tropical, subtropical and warm temperate waters of 61–72 °F (16–22 °C). Pygmies may prefer waters near the coast and continental shelf.[4]

Bryde's whales inhabit the Atlantic, Indian, and Pacific oceans, from 40° South to 40° North. Some populations migrate seasonally, moving towards higher latitudes during the summer and towards the equator during the winter. Uniquely among baleen whales, some populations do not migrate. The distribution of Omura's whales includes the nearshore and continental shelf waters of southeast Asia, east India, and the western Pacific.[4]

Population

There may be up to 90,000-100,000 animals worldwide, with two-thirds inhabiting the Northern Hemisphere.

For management purposes, the U.S. population is divided into three groups: the Eastern Tropical Pacific stock (11,000-13,000 animals), Hawaiian stock (350-500), and Northern Gulf of Mexico stock (25-40). There are an estimated 12 animals in the coastal waters of California, Oregon, and Washington.[4]

There are insufficient data to determine population trends

Conservation

Bryde’s whale is listed as Data Deficient by the International Union for the Conservation of Nature and Natural Resources (IUCN). It is also listed in Conservation on International Trade of Endangered Species of Wild Fauna and Flora (CITES) Appendix I, which prohibits international trade. Omura's whale is not listed by the IUCN.

Bryde's whales have not been reported as taken or injured in fishing operations. Historically, this species was not significantly targeted by commercial whalers, but became more important in the 1970s as the industry depleted other targets. The Japanese hunt this species as part of their scientific whaling program. Artisanal whalers have taken them off the coasts of Indonesia and the Philippines. Bryde's whales are also sometimes killed or injured by ship strikes. Anthropogenic noise is an increasing concern for all rorquals, which communicate via low-frequency sounds.[4]

The Marine Mammal Protection Act of 1972 protects these whales.[4]

Sightings

  • On August 23, 2007, a large whale with wounds in several body parts was found dead in waters off the town of Tagdon, Barcelona in Sorsogon province in the Philippines. The 14 metres (46 ft) long, 7 long tons (7.1 t) corpse was later identified as a Bryde's whale. This species frequents the coastal waters of the central Philippines, specifically the waters off Siquijor, Bohol, Palawan and Camiguin.[5][6]
  • On October 13, 2008, A 10 metres (33 ft)} long, 3 long tons (3.0 t) live Bryde's whale beached itself in the estuary of the Nenasi River, Pekan, Malaysia. Despite villagers' attempts to save it, the whale died.[7][8]
  • On October 4, 2009, a 41.5 feet (12.6 m)-long Bryde's whale died in Tampa Bay (Tampa, Florida, USA; [9]), and had to be removed from a busy shipping channel. Rescuers pulled the whale from the water onto the shore of Fort De Soto Park where a necropsy revealed fractured ribs and shredded muscle consistent with a boat strike. The whale was buried off shore by the park.[10]

[11]

See also

Bibliography

  • Baker A.N.; Madon B.(2007) Bryde's whales (Balaenoptera cf. brydei Olsen 1913) in the Hauraki Gulf and Northeastern New Zealand waters. Science for Conservation 272. p. 23. Department of Conservation, New Zealand. [2]
  • National Audubon Society Guide to Marine Mammals of the World, Reeves, Stewart, Clapham and Powell, 2002, ISBN 0-375-41141-0
  • Whales & Dolphins Guide to the Biology and Behaviour of Cetaceans, Maurizio Wurtz and Nadia Repetto. ISBN 1-84037-043-2
  • Encyclopedia of Marine Mammals, editors Perrin, Wursig and Thewissen, ISBN 0-12-551340-2
  • Whales, Dolphins and Porpoises, Carwardine (1995, reprinted 2000), ISBN 978-0-7513-2781-6

References

  1. ^ Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G.P., Urbán, J. & Zerbini, A.N. (2008). Balaenoptera_brydei. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 26 February 2009.
  2. ^ Olsen, 1913
  3. ^ Wada, Oishi, and Yamada, 2003
  4. ^ a b c d e f g h i j k l m n o "Bryde's Whale (Balaenoptera edeni)". http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/brydeswhale.htm. Retrieved December 2009.  
  5. ^ "42-ft-long whale found dead off Sorsogon". Home > Regions > Luzon (GMA News.TV). 23 August 2007. http://www.gmanews.tv/story/57389/42-ft-long-whale-found-dead-off-Sorsogon. Retrieved 2007-08-24.  
  6. ^ Labalan, Bobby (23 August 2007). "Whale beaches self, dies in Sorsogon". Breaking news > Regions (Inquirer.net). http://newsinfo.inquirer.net/breakingnews/regions/view_article.php?article_id=84256. Retrieved 2007-08-24.  
  7. ^ "Beached whale draws curious crowd". New Straits Times. 14 October 2008. http://www.nst.com.my/Current_News/NST/Tuesday/National/2374727/Article/index_html. Retrieved 2008-10-15.  
  8. ^ "Not the first such incident". New Straits Times. 15 October 2008. http://www.nst.com.my/Current_News/NST/Wednesday/National/2375519. Retrieved 2008-10-15.  
  9. ^ [1]
  10. ^ "Cause of death still unknown for Bryde's whale found in Tampa Bay". St. Petersburg Times. 6 October 2009. http://www.tampabay.com/news/environment/wildlife/article1041606.ece.  
  11. ^ "Necropsy shows whale found in Tampa Bay was killed by ship strike". St. Petersburg Times. 7 October 2009. http://www.tampabay.com/news/environment/wildlife/necropsy-shows-whale-found-in-tampa-bay-was-killed-by-ship-strike/1041955.  

External links


Simple English

Bryde's Whales

File:Bryde'

Size comparison against an average human
Conservation status
Data deficient (IUCN)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Eutheria
Order: Cetacea
Suborder: Mysticeti
Family: Balaenoptiidae
Genus: Balaenoptera
Species: B. brydei
B. edeni

Binomial name
Balaenoptera brydei
Olsen, 1913
Balaenoptera edeni
Anderson, 1879

The Bryde's Whale (Balaenoptera edeni) is a baleen whale and is unique in having 3 longitudinal ridges on its head, forward of the blowhole, while all other rorquals have just one. The whale can grow from 12.5m (41ft) to 14m (46ft) long and a weight of 26 tonnes, with the female larger than the male. There has often been confusion between the Sei whale and the Bryde's whale as they look alike and have the same size.


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