Bryde’s whale found dead after ship strike in the Gulf
21/04/2009 17:14:24
Decomposing Bryde's whale, found off Abu Dhabi, with signs of a ship strike. Photo credit EAD
Dead Whale recovered off Abu Dhabi
April 2009. A dead whale, identified as a Bryde's whale, has been recovered by a combined team of Environment Agency- Abu Dhabi (EAD) and Critical National Infrastructure Authority personnel about four nautical miles west of Umm Al Dalkh oil field on Friday 16 April 2009.
Ship strike
Thabit Al Abdessalaam, Director of Biodiversity Sector- Marine Environment at EAD said that the whale, which measured about 9 metres in length, was partially decomposed when found indicating that it may have been dead for at least 4 to 5 weeks. "Upon closer examination, the fluke (or tail) was found to be lacerated probably by a large boat propeller and may have been the cause of death" he said.
Subspecies
Some taxonomists think that there may be 3-4 distinctive forms of Bryde's whale populations. In the waters off the Arabian Gulf, Gulf of Oman and Northern Arabian Sea, two forms or subspecies-an offshore and a coastal form are thought to exist. The coastal, inshore type is perhaps entirely resident.
This species, which is a baleen whale, belongs to the family Balaenopteridae together with Humpback whale and Blue whale. The species, which is also commonly known as the Tropical whale, reflecting its preference for tropical and warm temperate waters, was given the common name, Bryde's whale in honor of Norwegian consul Johan Bryde, who built the first whaling factory in Durban, South Africa.
90,000 worldwide population
Although the species is included in IUCN Red List under the group of threatened species, its global population appears to be relatively stable. Current estimates put the population of the species globally to be around 90000. There is however a deficiency in terms of available data about the species at the local level in the UAE.
Bryde's whale attains a maximum length of 15.6 meters and weighs 20 tons with females being slightly larger than males. Females become sexually mature at 8-10 years of age. Males become sexually mature at the age of 9-13 years. The species probably mate throughout the year with females probably giving birth less than once every two years. Gestation lasts about one year.
Size at birth is 4.0 meters and the newly born weighs about one ton. Calves are weaned at about six months and approximately measure 7.1 m when they are weaned. The species is believed to breed in the region with observations of small calves 5-6 metres appearing to substantiate this fact.
DescriptionBryde's whale is distinguished from other members of family Balaenopteridae by having three prominent parallel ridges on the head with the central ridge being more pronounced and broader. Other members of the family possess only one ridge. Typical of baleen whales, Bryde's whale has two blowholes located on the top of the head. Flippers small compared to body size. The dorsal fin set about two-thirds of the way towards the tail along the body is prominent and sickle shaped. The fluke is small in relation to body size. Instead of teeth, there are an average of 300 short and broad baleen plates with uncurled stiff, grayish-white fringes occurring as two rows on the top jaw on each side. The species also has 40 to 50 characteristic pleated throat grooves. The color of the species is dark bluish to smoky-grey dorsally, and slightly paler below with the throat grooves partially yellowish-white. This species, which is thought to live between 50 to 70 years, is a gulp feeder and feeds on schooling fish (lanternfish, mackerel and sardines), krills and mantis shrimps. Bryde's whale mostly occurs solitary or in small groups of up to seven individuals but groups of up to 30 have been observed. The species is a relatively deep diver and may dive down to 300 metres, but usually dives less than 2 minutes although it is capable of dives of up to 20 minutes. The species communicates by way of moans, pulses, clicks, and grunts, as well as breaching. | DistributionAll three members of family Balaenopteridae occur in the waters of the region. Bryde's whale and to some extent the humpback whales, however, are more commonly encountered in these waters. The species is distributed through out the region from the Red Sea to the northern Arabian Gulf and constitute the region's most commonly encountered baleen whale. Its presence in the Gulf (of Oman) is particularly more frequent during winter months. |
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