#WhaleWednesday – Bryde’s Whale

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© Jirayu Tour Ekkul

The Bryde’s whale (pronounced “broo-dess”), is named after Johan Bryde who helped build the first whaling factory in Durban, South Africa in 1909. Sometimes known, appropriately, as the “tropical whale”, this is the only baleen whale species that lives all year-round in warmer waters near the equator.

The identity and number of species in the “Bryde’s whale complex” however is still unclear. In addition to the “ordinary” Bryde’s whale, with a worldwide distribution in the Pacific, Indian and Atlantic oceans, one or more smaller forms which tend to be more coastal in distribution have also been described. For the moment, the taxonomic status of the smaller forms is unclear and there may be several additional species and/or subspecies however currently two are recognized;  offshore Bryde’s whale, and Eden’s whale.

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© Jirayu Tour Ekkul

Bryde’s whales are closely related to several other fast swimming, medium-to-large whales all with a similar body shape and which may be confused with each other when viewed at sea. This group includes sei, minke and fin whales.

 

The Bryde’s whale has three parallel ridges on the top of its head. Like other rorqual whales, the Bryde’s whale has numerous grooves (between 40 and 70 throat pleats) running along the underside of the lower jaw to the belly which allow its mouth to expand when feeding. As with some of the other baleen whales, the Bryde’s whale primarily eats schooling fish and sometimes krill and other planktonic crustaceans. The Bryde’s whale has a slender body which is smoky blue-grey in colour with a sickle-shaped dorsal fin. The body is often mottled with some scars caused by parasites and/or cookie-cutter sharks. The flippers are slender, pointed and relatively short – approximately one tenth of their body length. The broad, distinctive tail flukes are rarely seen above the surface.

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The Bryde’s whale usually feeds alone, although mothers and calves often feed together. It is known to make sudden changes of direction when feeding both on the surface and underwater. Sometimes inquisitive, the Bryde’s whale can be seen approaching or swimming alongside boats. It has irregular breathing patterns, and will often blow four to seven thin, hazy spouts, followed by a dive, usually about two minutes long, although it is capable of staying below the surface for longer. They have also been see to blow or exhale whilst underwater. When surfacing between dives, the Bryde’s whale rarely shows more than the top of its head.

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© Jirayu Tour Ekkul

Bryde’s whales become sexually mature at 8-13 years of age and may mate year round. The peak of the breeding and calving season may occur in the autumn. Females breed every second year, with a usual gestation period of 11-12 months. Females give birth to a single calf that is about 11 feet (3.4 m) in length, that is nursed for about 6-12 months.

Wildlife

A long standing prohibition on the operation of factory ships north of 40°S, put in place to prevent hunting of rorqual whale’s at their lower latitude breeding grounds, allowed the Bryde’s whale to escape most of the historical exploitation of rorquals, as it occupies this region all year round. Only populations in the North Pacific may have been affected, as whaling vessels in this region were allowed to operate at lower latitudes, but even this threat was mitigated by the international moratorium on all commercial whaling implemented by the International Whaling Commission (IWC) in 1986. Although pelagic whaling by Japan was subsequently resumed in 2000, it is under scientific permit, and limited to catches of 50 individuals per year.

The main concern is that, while assessed as a single species, the Bryde’s whale appears to be abundant, but if it is in fact a complex of several separate species, some populations may be so small that they warrant threatened status and require conservation action.

Video: Bryde’s Whale Feeding in Raja Ampat

 

 

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