Bryde's Whale: Characteristics, Behavior, Feeding

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Byrde's whale

sBryde's whales (Scientific name: Balaenoptera edeni) are fast, sleek whales. They can grow to 15 meters (50) feet in length and weigh 20 tonnes (22 tons) — relatively small for a whale. They can travel at speed of 30 kilometers per hour (18 miles per hour) for short burst and dive to a depth of 300 meters (1,000 feet). An estimated 90,000 live around the globe, including 26,000 Western North Pacific Bryde’s Whales. They were never heavily hunted so their numbers never dropped to endangered levels as has been the case with other whales. [Source: Jennifer Holland, National Geographic]

Bryde's (pronounced "broodus" or "BROO-duhz") whales are members of the baleen whale family. They are considered one of the "great whales," or rorquals, a group that also 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. He was a whaling entrepreneur who first recognized that these whales were a different species. [Source: NOAA]

Bryde's whales are usually reported in warm, tropical waters. Members of the roqual family of baleen whales, they are long and thin and often mistaken for sei whales. They feed on krill and small schooling fish such as sardines and anchovies and less on plankton than other species. They sometimes participate with marlin and other large predators in feeding on schools of fish. Photographed Doug Perrine told National Geographic, “They’re hardly bloated, plankton-straining beasts puttering along at the surface...They’re sleek, predatory missiles.” He said diving with them was “like being on a train track in the fog, knowing a high speed locomotive could appear in an instant.”

Not much is known at about Bryde’s whales. Relatively small and lacking thick layers of blubber, they were never targeted much by whalers. There is little scientific data on them because they are hard to find. Bryde’s travel alone or in small groups. They don’t seem to have clear cut breeding and feeding areas as is the case with other baleen whales. They probably breed year round and my use low frequency calls to communicate with each other over long distances. Details about their migration patterns and mating habits are incomplete and often inferred from other whale species. Bryde's whales can live 50 to 70 years. The oldest recorded individual was 72 years old.

Websites and Resources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Fishbase; Encyclopedia of Life; Smithsonian Oceans Portal ; Monterey Bay Aquarium ; MarineBio

Bryde’s Whales Subspecies

Bryde’s whales were once considered monotypic (belonging to one species). Currently, there are two subspecies of Bryde’s. Bryde’s/Eden’s whale (Balaenoptera edeni edeni) is a smaller form found in the Indian and western Pacific oceans, primarily in coastal waters. The Bryde’s whale (Balaenoptera edeni brydei) is a larger form, found primarily in pelagic waters. Since 2003, the Bryde's whale's "pygmy form" has been recognized as a unique species — Omura's whale (Balaenoptera omurai). [Source: NOAA]

Byrde's whale range in blue

Each taxonomy subspecies has a different geographic distribution, genetic makeup, habitat, and physical appearance. Researchers are discussing whether the science supports recognizing the two subspecies as full species or whether additional data are needed to make that determination. Molecular evidence has suggested that the smaller coastal whales may be a different species than the larger whales that live in deeper waters.

Gulf of Mexico Bryde's whales (Balaenoptera eden, GoM subspecies) are a subspecies of the Bryde’s whale. With likely less than 100 individuals remaining, they are one of the most endangered whales in the world. Recovery of the species is dependent upon the protection of each remaining whale. These whales have been consistently located in the northeastern Gulf of Mexico, along the continental shelf break between 100 and 400 meters depth. They are the only resident baleen whale in the Gulf of Mexico and are distinct from Bryde’s whales worldwide. They weigh up to 30 US tons and reach lengths of 13 meters (41 feet). The Gulf of Mexico Bryde's whales are reproductively isolated and on a unique evolutionary trajectory. There is a low level of genetic divergence and they are not mixing with other Bryde’s whales.

Bryde's Whale Habitat and Where They Are Found

Bryde's whales have a wide distribution and occur in tropical, subtropical, and warm temperate waters 16° to 22°C (61° to 72°F) around the world. They live in all oceans from 40° south to 40° north. Some populations of Bryde's whales migrate with the seasons, 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. This is unusual among migrating baleen whales.[Source: NOAA]

Bryde's whales live in both coastal and pelagic (open ocean) creatures that usually follow their food sources. While pursuing prey, they have been observed diving as deep as 300 meters (985 feet). Sedentary populations include a small one with about 12 individuals along the coast of California. Molecular evidence has suggested that the smaller coastal whales may be a different species than the larger whales that live in deeper waters.

Scientists believe that the historical distribution of Gulf of Mexico Bryde’s whales once encompassed the north-central and southern Gulf of Mexico. For the past 25 years, Bryde’s whales in U.S. waters of the Gulf of Mexico have been consistently located in the northeastern Gulf of Mexico along the continental shelf break between 100 meters and 400 meters depth. This area has been identified as the Bryde’s whale Biologically Important Area The Gulf of Mexico Bryde’s whale do not migrate and remain in the Gulf of Mexico year-round. [Source: NOAA]

Bryde's Whale Physical Characteristics

Bryde’s whales range in length from 12 to 14 meters (39 to 46 feet) and range in weight from 12 to 25 tons (13 to 28 US tons, 12,000 to 25,000 kilograms, 26,000 to 56,000 pounds). Females are larger than males. Males range in size from 12 to 13 meters (39 to 42 feet), while females ranging from 13 to 14 meters (42 to 45 feet). These whales are endothermic (use their metabolism to generate heat and regulate body temperature independent of the temperatures around them).[Source: Jessica O'Grady, Animal Diversity Web (ADW) /=]

Bryde’s whales look similar to sei whales, but are smaller and prefer warmer waters. Unlike other rorquals, which have a single ridge on their rostrum, Bryde’s whales have three prominent ridges in front of their blowhole. Their bodies are sleek and their flippers are slender and pointed. The head of a Bryde's whale makes up about one quarter of its entire body length. The whales have a broad fluke, or tail, and a pointed and strongly hooked dorsal fin located about two-thirds back on the body. Bryde’s whales have 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. [Source: NOAA]

Bryde's whales are small rorquals, whales of family Balaenopteridae. Their body is a dark smokey grey on the top, which diffuses into a white below. Circular scars from lampreys and cookiecutter sharks have been spotted on the more migratory individuals. They have a distinctive V-shaped rostrum (beak) and have have three ridges on the top that run from the tip of their snout to the front of their blowhole. The throat grooves extend beyond their flippers to their navel. Inside their mouth, there are 285 to 350 slate gray coarse baleen plates on each side. The the longest plate is 40 centimeters. Bryde's whales have 54 to 55 vertebrae, along with 13 to 14 broad, thin ribs; the first rib is double-headed. Their dorsal fin is slightly curved or hooked, while the other fins are short, narrow, and pointed. Their flukes are wide and occupy 24 percent of the body length. Juveniles characteristics that are similar to those of adults. /=\

Bryde's Whale Behavior and Communication

Bryde’s whales are motile (move around as opposed to being stationary), migratory (make seasonal movements between regions, such as between breeding and wintering grounds), sedentary (remain in the same area) and usually solitary but sometimes social. Movements within their primary range, depend on the presence of food rather than breeding. Bryde's whales do not defend a territory. [Source: Jessica O'Grady, Animal Diversity Web (ADW) /=]

Bryde’s whales are usually seen alone or in pairs. Nonetheless, there have been reports of up to 20 whales loosely grouped together in feeding areas. Research suggests that Bryde’s whales spend most of the day within 50 feet of the water’s surface. They commonly swim at 1.6 to 6.5 kilometers per hour (one to four miles per hour), but can reach speeds of 17 to 25 kilometers per hoour (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 300 meters (1,000 feet). They do not display their flukes when diving. It is uncommon for Byrde’s whales to produce a visible blow. When they do, it is three to four meters tall and narrow.[Source: NOAA]

According to Animal Diversity Web: Those living near the shore may have feeding groups of 15 or less, while those living off-shore may have groups of up to 30. When they travel, 93 percent of Bryde's whales are solitary, a much greater percentage than the closely-related sei whales. However, Bryde's whales feed with many other whale species, interacting inter- and intra-specifically without aggression while feeding.

Bryde’s whales sense using vision, sound, touch, ultrasound and chemicals usually detected with smelling or smelling-like senses. Although they likely have no sense of smell, their vision and hearing appear to be similar to that of other cetaceans. They communicate with sound, mimicry, choruses (joint displays, usually with sounds, by individuals of the same or different species) and vibrations. Bryde's whales have been recorded emitting short, but loud, low-frequency moans. Most of the sounds they produce include two types of calls emitted simultaneously. They can repeat these calls every one to three minutes, and many are produced while the whales are moving. Whales call back and forth, and the type of calls differ with the size of the group. Gulf of Mexico Bryde’s whales produce a variety of highly stereotyped, low-frequency tonal and broadband calls for communication purposes. In the Gulf of Mexico, Bryde’s whale call types have been reported to be composed of downsweeps and downsweep sequences. [Source: NOAA]

Bryde's Whale Food and Eating Behavior

Bryde’s whales eat an estimated 600 to 660 kilograms (1,320 to 1,450 pounds) of food per day — which works out to about 4 percent of their body weight. Their diet consists of krill, copepods, red crabs, shrimp, as well as a variety of schooling fishes, such as herring, mackerel, pilchards, and sardines. Bryde's whales use different methods to feed in the water column, including skimming the surface, lunging, and creating bubble nets. 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. Additionally, Bryde’s whales can change directions unexpectedly when swimming. They sometimes generate short, powerful sounds that have low frequencies and sound like "moans."[Source: NOAA]

Gulf of Mexico Bryde’s whales spend the majority of their time within 16 meters (50 feet) of the water’s surface. They do not appear to forage at or near the surface but are thought to feed just at or above the seafloor. In general, Bryde's whales feed in the water column on small crustaceans and fish. These prey occur throughout the Gulf of Mexico.

Describing one feeding off Baja California Jennifer Holland wrote in National Geographic, “A long lean whale shoots up from the deep, chasing thousands of mackerel and sardines as they’re driven toward the surface by marlins and sea lions, Suddenly it lunges at the biggest mass of fish, mouth opening wide, throat pouch ballooning with seawater. Even against the tremendous drag created by its gaping maw, flicks of the whale’s muscular tail power it through the water. It jaws snap shut in an explosion of bubbles. Other hunters circle nearby, waiting for a turn at the feast.”

Bryde's whales are unique among whales in that have a generalist diet. This enables them to stay year-round in warm waters where food sources are often more diverse than those found in colder waters.. Although there is no evidence of communication while feeding, multiple whales are usually found in the same feeding location. Bryde's whales have been observed cleaning up after other predators by ingesting their leftovers. Inshore groups prefer fish, especially anchovies, sardines, mackerels, and herring, while the offshore groups tend to favor copepods and krill. They also eat cuttlefish, squid, and octopus. [Source: Jessica O'Grady, Animal Diversity Web (ADW) /=]

Researchers have witnessed predation by orcas (killer whales) and some shark species. When Bryde's whales are approached or pursued by a predator, they try to quickly swim away and outrun them. Bryde's whales host several parasitic species including parasitic worms, commonly called helminths. They sometimes host sea lampreys, which can cause death, due to organ failure caused by infections or blood loss.

Bryde's Whale Mating, Reproduction and Young

Bryde's whales are viviparous, meaning they give birth to live young that developed in the body of the mother, and engage in year-round breeding. Females breed every two to three years. The average number of offspring is one. The gestation period ranges from 11 to 12 months. The average weaning age is six months and the average time to independence is six months. Females and males reach sexual maturity at 10 to 13 years.[Source: Jessica O'Grady, Animal Diversity Web (ADW) /=]

Bryde's whales reach sexual maturity when they are 10 to 12 meters long. Bryde's whales can mate year-round. The peak of the breeding and calving season occurs in autumn. Sedentary inshore whales conceive throughout the year, while the more open ocean, offshore whales breed more often in the fall months. The first 4 months of pregnancy involves slow fetal development, while the remaining development is considerably faster.

Young are precocial. This means they are relatively well-developed when born. Parental care is provided by females. At birth, calves have an average length of 3.4 meters (10 feet) and weigh approximately 900 kilogram (one US ton). Calves nurse for about 12 months. At the end of the weaning period, the mother leaves the calf to fend for itself. [Source: NOAA]

Bryde's Whale, Humans and Conservation

At this time, there is not enough information to make a proper estimate of populations and population trends for the Bryde’s whales. International Union for Conservation of Nature (IUCN) Red List says that data is deficient to make determination of whether or not the species is endangered or threatened. The Convention on International Trade in Endangered Species (CITES) lists them in Appendix I, which lists species that are the most endangered among CITES-listed animals and plants, and Appendix II, which lists species not necessarily threatened with extinction now but may become so unless trade is closely controlled: All Bryde’s whales are protected under the Endangered Species Act (ESA, U.S. Fish and Wildlife) and Marine Mammal Protection Act (MMPA). In 2019, NOAA listed the Gulf of Mexico Bryde’s whale as endangered. [Source: NOAA]

Historically, Bryde’s whales were not major targets for commercial whaling. However, whalers have recently hunted Bryde’s whales off the coasts of Indonesia and the Philippines. Additionally, the Japanese continue to take Bryde’s whales as part of their scientific research whaling program. There have been reports that Japan lied about its Bryde's whale harvest to remain under the catch limits. From 1981 to 1987 harvest report from Japan indicated that 2,659 whales were caught, when in reality the harvested over 4,000. [Source: Jessica O'Grady, Animal Diversity Web (ADW) /=]

NOAA Fisheries marine mammal surveys have estimated the number of Gulf of Mexico Bryde’s whales to be 33 individuals. Recently, Duke University researchers estimated abundance to be 44 individuals based on the averages of 23 years of survey data. However, given the uncertainty about their existence in the southern Gulf of Mexico — particularly in Mexican and Cuban waters — scientists there are likely fewer than 100 individual Gulf of Mexico Bryde’s whales, with 50 or fewer being mature individuals. [Source: NOAA]

Threats to Bryde's Whale

Threats to Bryde’s whales include vessel strikes, ocean noise, whaling, energy exploration, development and production, oil spills and responses to oil spills.

Vessel Strikes: Accidental vessel strikes can injure or kill Bryde’s whales. They vulnerable to vessel strikes throughout their range, but the risk is much higher in coastal areas with heavy vessel traffic. Bryde's whales are the third most commonly reported species struck by vessels in the southern hemisphere. [Source: NOAA]

Accidental vessel strikes can injure or kill Gulf of Mexico Bryde’s whales. The northern Gulf of Mexico experiences a high amount of ship traffic where several commercial shipping lanes cross through Bryde’s whale habitat. In 2009, a female Gulf of Mexico Bryde’s whale was found dead in Tampa Bay. A necropsy was performed and its death was determined to be the result of being struck by a vessel. Because Bryde’s whales spend the most of their time within about 50 feet of the water’s surface they are particularly at risk of vessel strikes given the location of commercial shipping lanes, the whale’s swimming behavior, and the low ability of ships to change course quickly to avoid a whale. [Source: NOAA]

Ocean Noise: Low-frequency underwater noise pollution can interrupt Bryde’s whales’ normal behavior by hindering their ability to use sound. That disrupts their ability to communicate, choose mates, find food, avoid predators, and navigate. A variety of manmade sources in the Gulf of Mexico produce a significant amount of underwater noise. Shipping and energy exploration and development activities create low frequency noise, which overlaps with the hearing range of Bryde’s whales. It is likely that the Gulf of Mexico Bryde’s whales rely on their hearing to perform critical life functions such as communication, navigation, mate finding, food location, and predator avoidance. As marine noise increase, the resulting interruption to these life functions can result in adverse physical and behavioral effects to Gulf of Mexico Bryde’s whales.

Energy Exploration and Development: The Gulf of Mexico is highly industrialized due to expansive energy exploration and production that requires drilling rigs, platforms, cables, pipelines, and ship support. Vessel traffic and noise associated with these activities can modify or destroy Gulf of Mexico Bryde’s whale habitat. Habitat in the north-central and western Gulf of Mexico, which includes the Gulf of Mexico Bryde’s whales’ historical range, has already been significantly modified by the presence of thousands of oil and gas platforms.

Oil Spills and Responses: Oil spills are a common occurrence in the Gulf of Mexico. Exposure to oil spills may cause severe illness or death of marine mammals. Oil can get stuck in the baleen that the Gulf of Mexico Bryde’s whales use to eat. This makes it difficult for them to feed and can cause them to swallow oil. Exposure to oil spills can also lead to lung and respiratory issues, increased vulnerability to other diseases and infections, and irritation of the skin or sensitive tissue in the whale’s eyes and mouths. Additionally, oil spills can even have reproductive impacts.

Chemicals used to respond to oil spills, called dispersants, may also be toxic to Bryde’s whales. Whales continue to face threats from continued exposure to oil and dispersants in the environment long after the oil spill is considered over. Additionally, their prey is often killed or contaminated by the spill. The Deepwater Horizon oil spill showed how an oil spill can affect Gulf of Mexico Bryde's whales. While the DWH platform was located outside Gulf of Mexico Bryde’s whale habitat, scientists estimate nearly half of the oil spill footprint overlapped with the whales’ habitat. As a result, their population decreased by an estimated 22 percent.

Image Source: Wikimedia Commons, NOAA

Text Sources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated May 2023

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