Bryde’s whales (Balaenoptera edeni) are the least known and in many ways the most unusual of the rorquals, a group that includes blue whales and humpback whales. Bryde’s whales are named for Johan Bryde, a Norwegian who built the first whaling stations in South Africa in the early 20th century. “Bryde’s” is pronounced “broo-dess”. They belong to the genus Balaenoptera and the order Cetacea.
Bryde’s whales are currently considered monotypic (belonging to one species). Currently, there are two subspecies of Bryde’s whales. Eden’s whale (Balaenoptera edeni) is a smaller form found in the Indian and western Pacific oceans, primarily in coastal waters. The Brydes whale (Balaenoptera edeni brydei) is a larger form, found primarily in pelagic waters. Sometimes they are seen as separate species, although often, they are both labelled as Bryde’s whales.
Brydes whales are small by rorqual standards and weigh no more than about 25 tons although they are larger than the minke whale and very streamlined. Some populations of Bryde’s whales make short migratory movements with the seasons, while others do not migrate, making them unique among other migrating baleen whales.
Due to the lack of research on abundance and distribution, Brydes whales have been named “Data Deficient” on the IUCN Red List of Threatened Species. It is thought that they are not currently threatened, but may be at risk if not watched closely.
Bryde’s Whale Characteristics
Bryde’s whales closely resemble their close relative the sei whale, but they are smaller. They are long, with males ranging in size from 12 to 13 m. Females are slightly larger, ranging from 13 to 14 m in length. The head of a Bryde’s whale makes up about one quarter of its entire body length. Both sexes weigh 13,600 to 15,000 kg.
They have a broad head and a pointed dorsal fin located about two-thirds back on the body. The dorsal fin on the Brydes whale is quite large and falcated (curved back). Their bodies are sleek and heir flippers are slender and pointed. Colorwise, the Brydes whale is dark smoky gray dorsally and usually white ventrally. Some have a number of whitish-grey spots, which may be scars from parasites or shark attacks.
This whale has twin blowholes with a low splashguard to the front. Bryde’s whales often show their heads when at the surface of the water, where it is possible to distinguish three ridges that go along from the blow hole to the point. Like other rorquals, it has no teeth, but has two rows of baleen plates.
It also has 40 to 70 throat grooves on their underside that expand while feeding and 250 to 410 gray, coarse baleen plates on each side of their mouths that act as strainers while they feed. Brydes whales have 54 to 55 vertebrae, along with 13 to 14 broad, thin ribs.
Bryde’s Whale Lifespan
Bryde’s whales can live between 50 and 70 years in the wild.
Bryde’s Whale Diet
Bryde’s whales are different to other whales in their feeding habits. They have a generalist diet, which enables them to stay year-round in warm waters where they can always find food. Although they retain the characteristic plates of whalebone that the baleen whales use to sieve small creatures from the waters, their diet is composed almost entirely of fish. They eat school fish such as herring, mackerel, anchovies, pilchards, and sardines, and also eat, crustaceans, krill, copepods, red crabs and shrimp.
They also use lunging and bubble nets alongside skimming to catch their prey. Bryde’s whales eat an estimated 1,320 to 1,450 pounds of food per day, which equates to about 4% of their body weight.
Bryde’s Whale Behavior
Bryde’s whales are solitary animals and are usually seen alone or in pairs. Despite this, as many as 200 individuals have been seen together in feeding areas. They’ll also mix with other whale species while feeding.
Although it is uncommon for these whales to produce a visible blow, they occasionally do. Bryde’s whales can blow water 10 to 13 feet into the air when at the water’s surface. They sometimes exhale while underwater as well.
They spend most of the day within 50 feet of the water’s surface and swim for about 1 to 4 miles an hour, at a speed of around 12 to 15 miles per hour. They dive for about 5 to 15 minutes, with a maximum dive duration of 20 minutes, and can reach depths up to 1,000 feet. They do not display their flukes when diving. Bryde’s whales can change directions unexpectedly when swimming.
These whales are known to emit short, powerful sounds that have low frequencies. They sound like moans. Whales call back and forth to each other, but the baleen whales to not use echolocation.
The movements within their home range depend on the presence of food rather than breeding. Bryde’s whales do not defend a territory.
Brydes Whale Reproduction
It is assumed that Bryde’s whales have similar breeding habits to other cetaceans and are believed to breed year round. They become sexually mature when they are 10 to 12 m long and 10 to 13 years old. Their gestation period is estimated to be 12 months, and females give birth to one calf per season. Calves are about 4 metres long at birth and weigh 1,000 kilograms.
The calf nurses for around 6 months. At the end of the weaning period, the mother leaves the calf to fend for itself. Once the mother has given birth to a calf, she won’t breed again for another year.
Bryde’s Whale Location and Habitat
Bryde’s whales have a wide distribution and occur in tropical waters, subtropical waters, and warm temperate waters (61° to 72°F) around the world. They live in all oceans from 40° south to 40° north, including the Atlantic Oceans, Indian Oceans, and Pacific Oceans.
These animals are coastal and follow their food sources.
Bryde’s Whale Migration
Some populations of Brydes whale migrate, moving away from the equator during the summer and towards the equator during the winter. Other populations of Bryde’s whales are residents, meaning that they do not migrate.
Bryde’s Whale Conservation Status
Brydes whales conservation status has not been evaluated and the exact whale population is not known. They are listed as “Data Deficient” by the International Union for the Conservation of Nature and Natural Resources (IUCN). They are also listed on Conservation on International Trade of Endangered Species of Wild Fauna and Flora (CITES) Appendix I, which prohibits international trade.
Bryde’s whales are protected under the Marine Mammal Protection Act (MMPA), which prohibits the removal of marine mammals from U.S. waters and their importation into the U.S. Their biggest threats are commercial whaling, collisions with vessels and becoming entangled in fishing gear. There is worry climate change will change the ecosystem in their waters, too, which will affect their food sources. Noise pollution underwater may also have an effect on these animals, because it interferes with their ability to communicate with one another, find food and avoid predators.
Unfrotuntely, because Bryde’s whales look similar to minke whales, they are often mistaken and caught for food.
Bryde’s Whale Predators
The Bryde’s whale is preyed on by killer whales and some shark species. Their only defence when approached by predators is to swim away quickly.
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