Bryde’s Whales, the most unusual of the rorquals
Bryde’s whales are baleen whales or rorquals that live in the tropical and temperate waters. They prefer coastal areas and were named after a Norwegian Entrepreneur Johan Bryde who helped with setting up a whaling station in Durban, South Africa in 1908.
There may be an estimated 90,000 to 100,000 of these individuals in the world, however the data available is insufficient in order to determine the population of these whales. They are listed as data deficient on the IUCN list.
Scientific Classification (Taxonomy):
List of Abbreviations and terms used:
IUCN – International Union for the Conservation of Nature and Natural Resources
CITES – Convention on International Trade in Endangered Species of Wild Fauna and Flora
CMS – Conservation of Migratory Species of Wild Animals.
IWC – International Whealing Commission
MMPA - Marine Mammal Protection Act
DD – Data Deficient (Inadequate information to make a direct or indirect assessment of its risk of extinction based on its distribution or population status or both)
Baleen Whales – Whale with plates of whalebone along the upper jaw for filtering plankton from the water
Rorquals – Any of several baleen whales of the family Balaenopteridae having longitudinal grooves on the throat (folds or grooves of skin below the mouth) and a small pointed dorsal fin
Rostrum – Beaklike projection of the anterior part of the head (nose)
Flukes – Either of the two lobes of the tail of a cetacean
Dorsal – upper surface of an animal
Ventral – lower surface of an animal
Blowholes - The breathing orifice of a cetacean located far back on the skull
Gestation – state of being pregnant
Moratorium - legally authorized postponement or suspension of an ongoing activity
IUCN – Data Deficient (DD)
CITES – Appendix I that prohibits International trade
CMS – Appendix II because of its unfavourable conservation status.
Characteristics and behaviour of the Bryde’s whales:
- The bryde’s whales are of moderate size measuring almost 13 to 16.5 m long (males around 13.7 m and females around 14.5 m). The females (cow) are slightly larger than the males (bull) and these whales have a streamlined body
- They weigh between 16 to 18.5 tonnes, have twin blowholes with a low splashguard at the front.
- They have no teeth, but 2 rows of baleen plates, are dark grey in colour on the dorsal side and the ventral side is white. They have white patches on the throat and chin.
- They have a straight rostrum (tip of the head) that has three longitudinal ridges that extend from the blowholes near the rear of the head to the tip of the rostrum.
- Their lower jaws are dark grey in colour with 250 to 410 pairs of baleen plates that have long coarse bristles along the inner edge that are light grey or white. The bristles are around 40 to 50 cm long and 19 to 20 cm wide and are used to trap food.
- There are 40 to 70 ventral pleats (many grooves that run under the lower jaw to the belly helping it to expand when swallowing water while it’s feeding) that occupy almost 58% of the total body length.
Bryde's whale (Balaenoptera brydei)
- Their dorsal fin is upright and is around 46 cm tall, sickle shaped and there is a central notched tail fluke.
- They have small flippers that are thin.
- Their blow is either columnar or bushy and can reach up to a height of 3 to 4 m. They blow either on the surface of water or under water.
- They come to the surface at irregular intervals and can change directions without any reason. They dive for 5 to 15 and sometimes 20 minutes after every 4 to 7 blows.
- They can dive down to a depth of about 300 m and swim at the speed of 1.6 to 6.4 km per hour. They can swim as fast as 19 to 24 km per hour.
- They are found alone or in pairs (mother and calf) or sometimes in a group of around twenty while feeding.
- They sometimes create sounds of low frequency that sound like moans
How do the Bryde's whales feed?
The Bryde’s whales use different feeding methods like lunging, skimming the surface and by creating bubble nests. They lung forward towards a shoal of fish with their mouth opened, swallowing a huge amount of water and fish. The grooved area under the jaw expands to accommodate this. The whale then closes the mouth and allows the water to escape through the baleen fibres that trap the food inside the whale’s mouth . The whale then swallows the food.
Habitat and food of the Bryde’s Whales:
The bryde’s whales are found in the tropical and temperate waters of temperature around 16 to 22 degree Celsius. They are mostly found in the Atlantic, Pacific and Indian oceans. They may sometimes migrate to higher altitudes during summer and then back towards the tropics during winter but mostly remain in the same location throughout the year.
They eat plankton, crustaceans like crabs and shrimps, fish that are found as a school like anchovy, sardines, mackerel, etc and hence are found in areas where there are plenty of fish.
They eat around 600 to 660 kg of food a day
Reproduction in Bryde’s whales:
- They attain sexual maturity when they are 8 (females) to 12 or 13 (males) years old and the males are around 11.9 m long and females are around 12 m long when they are mature.
- They breed once every two years all through the year. Breeding is at its peak mostly during Autumn and Winter.
- The gestation period is 12 months and they give birth to one calf. The young ones are 3.95 to 4.25 m long at birth, weigh around 1 tonne and are looked after by the mother for 6 to 12 months.
- These whales live for up to 50 to 70 years.
Threats for the Bryde's whales:
- Commercial whalers have targeted these whales since 1970
Whale watching La Gomera: Bryde's Whale
- These whales are hunted in Japan as part of the scientific whaling program (limited to 50 per year).
- They have been hunted in huge numbers along the coasts of various countries like Philippines, Taiwan, Norway, Peru, Chile, Cape Province in South Africa, Brazil etc, leading to the decline in the population of these whales in varying percentages across the world.
- Skilled hunters have hunted and taken these whales off the coast of Indonesia and Philippines.
- They are in abundance when assessed as a single species, but when taking the several subspecies into account, some subspecies may be endangered and need conservation
- These whales also get injured during ship strikes.
- Anthropogenic noise and other underwater sounds are another concern for these whales as they communicate using low frequency sounds.
Conservation and Protection for the Bryde's whales:
- These whales are protected by the MMPA of 1972 in the USA.
- They are listed on Appendix I of CITES and hence international trade on these whales is illegal.
- International moratorium has been implemented on all commercial whaling by the IWC in 1986
Facts about the Bryde’s whales:
- A population survey done during the 1990s in the North pacific area showed a decline in the population of these whales by 49% between 1911 and 1996.
- A group of bryde whales is called a gam or pod or herd
- They are the second smallest of the rorquals
- They are the only whales with three ridges on their head