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Balaenoptera brydei

Balaenoptera brydei is a species of cetacean, marine mammals, in a complex group known as the Bryde’s whales. They are the least-known and in many ways the most unusual of the rorquals. They are small by rorqual standards—no more than about 25 tonnes—prefer tropical and temperate waters to the polar seas that other whales in their family frequent; are largely coastal rather than pelagic, and although they retain the characteristic plates of whalebone that the Mysticeti use to sieve small creatures from the waters with, their diet is composed almost entirely of fish.

The Bryde’s whale is named for the Norwegian consul to South Africa, Johan Bryde, who helped set up the first whaling station in Durban, South Africa in 1908.

Bryde’s whales feed on pelagic schooling fish, such as anchovy, herring and sardine.

They are distributed widely throughout tropical and subtropical waters, with a separate, smaller, pygmy species found in tropical Western Pacific and South-East Asia.

Taxonomy[edit]

Baleen plate of Bryde's whale.

The population currently described as Balaenoptera brydei is part of a group with taxonomic confusion resulting from disputed systematics and misidentification, sometimes termed the Balaenoptera edeni complex after the early description Balaenoptera edeni Anderson, 1879. The group are very similar in appearance to sei whales (Balaenoptera borealis), and almost as large, and commercial whaling harvests termed all these as Bryde's whale until the 1970s. Specimens of Balaenoptera omurai have also been identified by the common name 'Bryde's whale'. The taxa are poorly known and further research is required to resolve the arrangements of these sister groups.[2]

Phylogenetic evidence suggests that it is closely related to B. edeni, but they may be separated as sister species. The names and distribution of these may be summarised as:

  • Balaenoptera brydei, Bryde’s whale. A worldwide tropical and semi-tropical distribution, grows to 26 tonnes and 15 metres long.
  • Balaenoptera edeni; Eden's whale, small-type Bryde's whale, pygmy bryde's whale. Found in coastal waters of the eastern Indian and western Pacific oceans.

However, a recommendation to the International Whaling Commission in 2006 suggested B. brydei should be recognised and named B. edeni.[3] Likewise, MSW3 list this name as a synonym, but acknowledges the earlier revision (Rice, 1998). The authors note further confusion over which of the proposed species is the smaller, the lack of a type specimen, and the need to split B. omurai if revised.[4] The database ITIS lists all three as valid taxa, with a similar caveat on Balaenoptera systematics.[5]

Balaenoptera edeni described a stranded specimen on the coast of Burma in 1878. In 1913 whales off the coast of South Africa were described as Balaenoptera brydei; the name commemorates Johan Bryde, a Norwegian consul and pioneer of the South African whaling industry.[6]

By the 1950s, it was thought that they were a single species, which became B. edeni (because the first proposed name for any species always has priority) but retained Bryde's whale as the common name.[who?] Recent genetic work, however, indicates that there are in fact two separate species:[7]

"Bryde" is pronounced /ˈbrdə/ BREW-də, and "Bryde's whale" is sometimes misheard as "brutus whale". Five different types have been identified, including at least two smaller ones that tend to stay closer inshore. Alas from the point of view of taxonomic simplicity, DNA testing shows that the newly confirmed pygmy species of South-east Asia is not the same as the similar-looking small form found in the Caribbean. Complicating matters still further, there are forms which appear to be intermediate between Bryde's whale and the sei whale.[citation needed]

The conservation status of Balaenoptera brydei may be listed and discussed as a subgroup of B. edeni; it is listed as Data Deficient by the IUCN,[1] and by CITES Appendix I, which prohibits international trade.

Description[edit]

The descriptions of Balaenoptera brydei are complicated by its systematic arrangement and lack of research. The species is a smaller member of the family, up to 11.5 metres (37-ft), whereas B. edeni reaches 15.5 (50-ft), male and female dimorphism is around half a meter. This species is also described as a smaller coastal dwelling form of the latter.[2]

In general, Bryde's whales have a very broad and short head, with between 40 and 70 ventral grooves, and relatively large eyes.

The Bryde’s whale is in the rorqual family (Balaenopteridae) of baleen whales and is unique amongst these in that it has three longitudinal ridges on its head, from the tip of the snout back to the blowhole – the other rorquals have just one ridge.[2]

The whale 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 prominently curved, pointed dorsal fin is readily seen when a Bryde's whale surfaces. The flippers are small and slender; the broad, centrally notched tail flukes never break the surface.

Colour varies: the back is generally dark grey or blue to black, the ventral area 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.

Bryde’s whales are believed to breed year round and their gestation period is estimated to be 12 months. Calves are about 4 m (13-ft) long at birth and weigh 1,000 kg.[clarification needed]

See also[edit]

Bibliography[edit]

  • 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. [1]
  • 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
  • Rice, D.W. (1998). Marine mammals of the world. Systematics and distribution. Special publication number 4. Kansas: Society for Marine Mammalogy.

References[edit]

  1. ^ a b 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 edeni. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 26 February 2009.
  2. ^ a b c Balaenoptera edeni, Species Profile and Threats Database, Department of the Environment and Heritage, Australia.
  3. ^ Perrin, W.F. & R.L. Brownell, Jr (2006).Proposed Updates to the List of Recognised Species of Cetaceans.
  4. ^ Balaenoptera edeni Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  5. ^ "Balaenoptera brydei Olsen, 1913". Integrated Taxonomic Information System. 
  6. ^ Named after a Norwegian diplomat, The Star, December 16, 2006.
  7. ^ SPRAT, citing: Sasaki, T., M. Nikaido, S. Wada, T.K. Yamada, Y. Cao, M. Hasegawa & N. Okada (2006). Balaenoptera omurai is a newly discovered baleen whale that represents an ancient evolutionary lineage. Molecular Phylogenetics and Evolution. 41 (1):40-52.

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