Bryde's whale
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Classification:
Population mondiale
Description Et Histoire Naturelle
Physical DescriptionThe Bryde’s whale (pronounced Broodahs) is a baleen whale from the family Balaenopteridae – the rorqual whales. A rorqual whale – such as fin, minke, blue, sei and humpback – has folds or grooves on its throat and chest to allow the mouth to expand when filled with water. The term rorqual supposedly comes from the Norwegian "ror" (tube) and "hval" (whale); so named because the throat folds or grooves look like tubes in cross-section.
The Bryde's whale is named after a Norwegian consul to South Africa, Johan Bryde, who helped build the first whaling factory in South Africa in the early 1900s.
It is acknowledged that the current classification of the Bryde’s whale includes more than one species, but there is still uncertainty about how many species there are. Like the minke, sei, fin and blue whales included in this family, the Bryde’s has a slender body and a broad flat head.
The Bryde’s whale is the second smallest rorqual, growing to between 12.5 meters (41 feet) and 14 meters (46 feet), and weighing up to 26 tonnes (29 tons). Females are slightly larger than males. Bryde’s whales have two blowholes and three parallel ridges running from the blowholes to the snout.
They are usually dark gray or bluish gray. Some individuals have a lighter gray area between the head and dorsal fin, and sometimes a light band down the side, from the fins to the flukes. The belly and chin are also light-colored. The skin can be scarred and mottled. The throat grooves are yellowish and end at about the navel.
Their fins are short, their flukes broad and notched. The Bryde's whale's dorsal fin is located about two-thirds of the way toward the flukes and is tall and sickle-shaped.
As with all baleen whales, Bryde’s whales do not have teeth. There are between 250 – 410 baleen plates (about 15 centimeters long and 20 centimeters wide) which may be separated at the front of the mouth by a gap. Most baleen is black or dark gray, although near the front of the mouth, it may be cream-colored.
Natural History
Bryde’s whales are distributed widely throughout tropical and subtropical waters, but their distribution and migration patterns are poorly known. A separate, smaller, pygmy species lives in the tropical Western Pacific and Southeast Asia.
It is thought that Bryde’s whales breed throughout the year, giving birth to a single calf weighing 900 kilograms (1,985 pounds) and measuring four meters (13.3 feet) in length. Sexual maturity is thought to be reached somewhere between eight and ten years of age. These whales are lunge feeders, taking in large amounts of water and prey (such as schooling fish and krill) which they filter out through their baleen. They often feed alone or in pairs but can be found in groups of ten to 20 on feeding grounds. Bryde's whales rarely show their flukes above the water. Their blow can be tall and thin, but they can also exhale under water and surface with little or no blow. Bryde's whales may approach boats.
The International Whaling Commission has no accepted population estimate for the Bryde’s whale.
Situation De L'Espèce
StatusBryde’s whales are listed as Data Deficient by the International Union for the Conservation of Nature and Natural Resources (IUCN). They are listed on Appendix I of the Conservation on International Trade of Endangered Species of Wild Fauna and Flora (CITES).
Threats to the Species
It is difficult to distinguish the history of whaling for this species because the sei and Bryde’s whales were combined in the catch statistics until 1972. However, it is clear that most commercial whaling took place in the western Pacific where 15,076 animals were landed between 1946 and 1983. Between 1973 and 1981, 2,873 Bryde’s whales were landed from the eastern Pacific. In addition, 2,304 sei or Bryde's whales were taken in the eastern Pacific between 1968 and 1972.
In 2000, Japan resumed whaling for the Bryde’s whale in the North Pacific, taking 43 that year and 50 in 2001. Taking Bryde’s whales has not been permitted since the suspension of commercial whaling by the International Whaling Commission (IWC) in 1986, but these whales were killed as part of Japan’s "scientific" whaling program under special permit. Bryde’s whales may become entangled in fishing gear and have been struck by ships. Increasing noise pollution is a concern, as is chemical pollution.
International Trade
Listed on CITES Appendix I
which prohibits international
trade.
Auteur Et Sources
SourcesAnonymous. 1999. Bryde’s whale.
Discovering Whales. The Bryde’s whale. http://whales.magna.com.au/DISCOVER/BRYDES/brydesg.html
IFAW. 2001. Whale kills since 1990. http://www.stopwhalingnow.com.
IUCN. 2001. The 2000 IUCN Red List of Threatened Species. http://www.redlist.org
Jefferson, T.A., S. Leatherwood and M.A. Webber. 1993. Marine mammals of the world. FAO Species Identification Guide. UNEP, Rome. 320pp.
Mammals of Texas. 1997. Bryde’s whale. http://www.nsrl.ttu.edu/tmot1/balaeden.htm
Southwest Fisheries Science Center. http://swfsc.ucsd.edu/sars/Brydes_w.htm
IWC. 2001. Journal of Cetacean Research and Management 3 (Suppl.):364.
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Bryde's Whale. Photo © Benjamin Kahn/APEX Environmental
