Fin Whales: Characteristics, Behavior, Subspecies, Feeding

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fin whale
Fin whales (Scientific name: Balaenoptera physalus) are the second largest and longest species of whale after blue whales. They are widely distributed in all the world's oceans and get their name from an easy-to-spot fin on its back, near their tail. The lifespan of fin whales is 80 to 90 years. but there are reports of fin whales that have lived in excess of 100 years, maybe even 114 years. [Source: Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW), ] [Source: NOAA]

Also known as finback whales, fin whales are members of the roqual family of baleen whales. They reach lengths of 27.4 meters (90 feet) but are generally between 18.2 and 24.4 meters (60 to 80 feet). They are also among the fastest of the great whales. They can travel at speeds of up to 20 knots. In the whaling era they left sailing ships far behind and were not caught until steam-powered catcher boats came into use. Fin whales also produce one of the highest spouts of any whale — six meters (20 feet).

Fin whales are identified by a stripe-like groove on the skin of the whale’s throat, distinct coloring on their jaw, and the unique size and placement of the fins. Fin whales produce a extremely loud cracking noise when with their jawbones when they open their mouths. This loud noise is believe to stun its prey and make them easier to swallow. Fin whales feed on krill, plankton and fish. Like blue whales, they are gulpers. They filter great mouthfuls of sea water and everything in it. They keep krill from swimming out their open mouths by producing a loud cracking noise with their jaws that scare the krill into seeking refuge in the middle of the mouth where they are doomed.

Like all large whales, fin whales were hunted by commercial whalers, which greatly lowered their population. Whalers did not target them at first, because of their speed and open ocean habitat. But, as whaling methods modernized with steam-powered ships and explosive harpoons, whalers over-hunted other species of whales they had used for oil, bone, and fat. They turned to fin whales, killing a huge number during the mid-1900s — 725,000 in the Southern Hemisphere alone. Present numbers are thought to be 50,000 to 120,000, with an estimated 56,000 in the the North Atlantic. Adult fin whales have no natural predators. Young fin whales may be targeted by large predators, such as killer whales, although fin whales groups are likely to be able to defend their young. [Source: NOAA]

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

Fin Whale Habitat and Where They Are Found

Fin whales are found in all major oceans and open seas, including the Atlantic Ocean, Pacific Ocean, Indian Ocean and Mediterranean Sea. They live in deep temperate, tropical, polar, saltwater and marine environments and are found in coastal areas and in the open ocean far from land. They typically dive at depths of 200 to 250 meters (656 to 820 feet). They are more often found in temperate and polar zones and less commonly seen in tropical oceans and seas. [Source: Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW) /=]

Fin whales occur year-round in a wide range of locations, but the density of individuals in any one area changes seasonally. Most migrate from the Arctic and Antarctic feeding areas in the summer to tropical breeding and calving areas in the winter. The location of winter breeding grounds is not known. Fin whales travel in the open seas, away from the coast, so they are difficult to track. [Source: NOAA]

fin whale range in blue

Some populations of fin whales are migratory, making seasonal movements between colder waters during the spring and summer months to feed. In autumn, they return to temperate or tropical oceans. Because of the difference in seasons in the northern and southern hemisphere, northern and southern populations of fin whales do not approach the equator at the same time during the year. Other populations are sedentary (remain in the same area), staying in the same area throughout the year. Non-migratory populations are found in the Mediterranean Sea and the Gulf of California. /=\

In the southern hemisphere, fin whales enter and leave the Antarctic throughout the year. Larger and older whales tend to travel further south than younger ones. During the summer in the North Atlantic Ocean, fin whales are found from the North American coast to Arctic waters around Greenland, Iceland, north Norway, and into the Barents Sea. In the winter these fin whale populations are found from the ice edge toward the Caribbean and the Gulf of Mexico and from southern Norway to Spain. In summer in the North Pacific Ocean, fin whales migrate to the Chukchi Sea, the Gulf of Alaska, and coastal California. In the winter, they are found from California to the Sea of Japan, East China and Yellow Seas, and into the Philippine Sea. /=\

Fin Whale Populations, Species and Subspecies

Today, there are about 2,700 fin whales in the North Atlantic and Gulf of Mexico and about 3,200 in the waters off of California, Oregon, and Washington (the eastern Pacific Ocean). The estimate for the entire North Pacific is between 14,000 and 18,000. The number of fin whales in the southern hemisphere is around 82,000. [Source: NOAA]

For management purposes, NOAA divide fin whales in U.S. into four stocks: 1) Hawaii; 2) California/Oregon/Washington; 3) Alaska (Northeast Pacific); and 4) Western North Atlantic NOAA determines the number of fin whales through counting stocks, however, there is not accurate information for all stocks. Reliable, recent estimates are available for much of the North Atlantic Ocean, but not for most of the North Pacific or the Southern Ocean. We do not know how populations in those ocean basins have changed, relative to their pre-whaling size. The most recent population assessments can be found in stock assessment reports. [Source: NOAA]

There are three named subspecies of fin whale: 1) B. physalus physalus in the North Atlantic and North Pacific; 2) B. physalus quoyi in the Southern Ocean; and 3) B. physalus patachonica in the mid-latitude Southern Ocean.

In fact, most experts consider the B. physalus physalus in the North Atlantic and the North Pacific to be separate subspecies. The two populations rarely (if ever) mix, and there are geographical stocks within these ocean basins. Fin whales are migratory, moving seasonally into and out of feeding areas near the poles, but the overall migration pattern is complex and specific routes have not been documented. However, acoustic recordings from passive-listening hydrophone arrays indicate a southward “flow pattern” in the fall from the Labrador-Newfoundland region, past Bermuda, and into the West Indies. There may be resident groups of fin whales in some areas, such as the Gulf of California, the East China Sea, and the Mediterranean Sea.

fin whale

Fin Whale Physical Characteristics

Fin whales range in length from 19 to 27 meters (62 to 88 feet), with their average length being 24 meters (78.74 feet). They weigh 40 to 80 US tons (36,290 to 72,575 kilograms, 36.3 to 72.6 tonnes). Their average weight is 77 US tons (70,000 kilograms, 70 tonnes), Sexual Dimorphism (differences between males and females) is minimal: Both sexes are roughly equal in size and look similar. These whales are endothermic (use their metabolism to generate heat and regulate body temperature independent of the temperatures around them) and homoiothermic (warm-blooded, having a constant body temperature, usually higher than the temperature of their surroundings). [Source: Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW) /=]

Fin whales have a sleek, streamlined body with a V-shaped head. They have a tall, hooked dorsal fin, about two-thirds of the way back on the body, that rises at a shallow angle from the back. Fin whales have distinctive coloration: black or dark brownish-gray on the back and sides, white on the underside. Head coloring is asymmetrical — dark on the left side of the lower jaw, white on the right-side lower jaw, and the other way around on the tongue. Many fin whales have several light-gray, V-shaped “chevrons” behind their heads; on many of them, the underside of the tail flukes is white with a gray border. These markings are unique and can be used to identify Individual fin whales. [Source: NOAA]

According to Animal Diversity Web: Size varies geographically: southern hemisphere whales are roughly 20 meters (66 feet) long, while northern and Arctic fin whales reach up to 25 meters (82 feet) in length. Fin whales can be distinguished from other whales by the medium-sized white patch on their lower, right jaw. The base of the tail is raised, causing their back to have a distinctive ridge. The white underside wraps around to their midsection laterally. The dorsal fin is 50 centimeters in height, curved, and found relatively far back on the body. The head is quite flat and represents about 1/5 of total body length. These whales have two blowholes and a single, longitudinal ridge extends from the tip of the snout to the beginning of the blowholes. Fin whales are able to expand their mouths and throats during feeding because of the roughly 100 pleats that run from the bottom of their bodies to their mouths. These pleats allow the mouth cavity to engulf water during feeding. Fin whales are filter feeders, with between 350 and 400 baleen plates that are used to catch very small to medium-sized aquatic life suspended in the water. /=\

Fin Whale Behavior, Swimming and Diving

Fin whales are diurnal (active during the daytime), nocturnal (active at night), motile (move around as opposed to being stationary), migratory (make seasonal movements between regions, such as between breeding and wintering grounds) and social (associates with others of its species; forms social groups). Their average territory size is more than 2000 square kilometers. Home range sizes have not been established. Fin whales migrate over long distances throughout the year. In spring and early summer they usually reside in colder feeding waters, in fall and winter they return to warmer waters to mate. [Source: Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW) /=]

fin whale

Fin whales are among the most sociable species of whales. They are often found in social groups of two to seven or family groups of six to 10 members. Occasionally fin whales form groups of nearly 250 individuals near feeding grounds or during migration periods. In the North Atlantic, they are often seen feeding in large groups that include humpback whales, minke whales, and Atlantic white-sided dolphins. [Source: NOAA /=]

Fin whales are fast swimmers. They have long been recognized for their speed and are one of the fastest marine mammals. They have a cruising speed of 5 to 10 kilometers per hour (8 to 16 miles per hour) and a “sprinting” speed of nearly 40 kilometers per hour (25 miles per hour) often seen when feeding. Fin whales can dive up to depths of roughly 250 meters (820 feet) and stay underwater for nearly 15 minutes.

Fin Whale Perception and Communication

Fin whales sense using vision, sound, touch, ultrasound and chemicals usually detected with smelling or smelling-like senses. They communicate with sound and employ choruses (joint displays, usually with sounds, by individuals of the same or different species) to communicate. [Source: Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW) /=]

Like blue whales and humpback whales, fin whales communicate through vocalizations. Male fin whales make extremely low frequency sounds that are among the lowest sounds made by any animal. According to Animal Diversity Web: Fin whales produce low frequency sounds that range from 16 to 40 Hz, outside of the hearing range of humans. They also produce 20 Hz pulses (both single and patterned pulses), ragged low-frequency pluses and rumbles, and non-vocal sharp impulse sounds. Single frequencies (non-patterned pulses) last between one and two minutes while patterned calling can last for up to 15 minutes. The patterned pulses may be repeated for many days. /=\

Higher frequency sounds have been recorded and are believed to be used for communications between nearby fin whales and other pods. These high frequencies may communicate information about local food availability. The 20 Hz single pulses help whales communicate with both local and long distances members and patterned 20 Hz pulses are associated with courtship displays. A study done about the sound frequencies of fin whales suggest that whales use counter-calling in order to get information about their surroundings. Counter-calling is when one whale of a pod calls and another answers. The information conveyed by the time it takes to answer as well as the echo of the answer is believed to hold a lot of important information about the whale’s surroundings. /=\

Fin Whale Food and Eating Behavior

Fin whales primarily feed on fish, krill, squid and plankton-sized animals including crustaceans. Like blue whales and other baleen whales, they are filter feeders that consume food by filtering prey out of the water that they swim through. Typically, they skim the water, taking in huge volumes of water. When they close their mouths, the water is pushed out through the baleen and the prey is caught on the inside of the baleen. A fin whale eats up to 2 tons of food every day this way. Fin whales occasionally swim around schools of fish to condense the school so that they increase their catch per dive. [Source: NOAA, Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW) /=]

During the summer, fin whales feed on krill, small schooling fish (including herring, capelin, and sand lance), and squid by lunging into schools of prey with their mouth open, using their 50 to 100 accordion-like throat pleats to gulp large amounts of food and water. They then filter the food particles from the water, using the 260 to 480 baleen plates (long, flat plates made of fingernail-like material) they have in place of teeth on each side of the mouth. Fin whales fast in the winter while they migrate to warmer waters. [Source: NOAA]

A study published in 2021 off the U.S. West Coast showed fin whales eat 6-12 tons of krill daily, while blue whales eat about 10-20 tons of krill and humpback whales eat 5-10 tons of krill or 2-3 tons of fish a day. The study found that the whales primarily feed at depths of 50 to 250 meters (165 to 820 feet). [Source: New York Times]

Fin Whale Reproduction and Mating

Fin whales are viviparous, meaning they give birth to live young that developed in the body of the mother. They engage in seasonal breeding every two to three years. The breeding season is from November to January in the northern hemisphere and June to September in the southern hemisphere. The number of offspring is usually one. The gestation period ranges from 11 to 12 months. The weaning age ranges from six to seven months and the age in which they become independent ranges from six to eight months. Females reach sexual maturity at seven to 12 years. Males reach sexual maturity at six to 10 years. [Source: Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW) /=\, NOAA]

Little is known about the social and mating systems of fin whales. As with other baleen whales, long-term bonds between individuals are rare. Fin whales have long lives: they reach physical maturity at about 25 years, and their maximum lifespan is about 90 years. Fin whales sometimes mate with blue whales and hybrids have been documented.

According to Animal Diversity Web: Fin whales are seen in pairs during the breeding season and are believed to be monogamous. There have been sightings of courtship behavior during the breeding season. A male will chase a female while emitting a series of repetitive, low-frequency vocalizations, similar to humpback whale songs. However, these songs are not as complex as those observed in humpback whales or gray whales. One study has shown that only males produce these low-frequency sounds. Low frequencies are used because they travel well in water, attracting females from far away. This is important because fin whales do not have specific mating grounds and must communicate to find each other. /=\

Fin Whale Young and Development

Pregnant fin whale females typically gives birth to a single calf in tropical and subtropical areas during midwinter after an 11 to 12 month gestation period. Newborn calves are about 5.5 meters (18 feet) long, and weigh two to three US tons (4,000 to 6,000 pounds, 1,815 to 2721 kilograms). [Source: NOAA]

Although there have been reports of fin whales giving birth to multiple offspring, it is rare and those offspring rarely survive. After raising her young the mother undergoes a resting period of five or six months before mating again. This resting period may extend to a year if the female fails to conceive during the mating period. [Source: Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW) /=]

Pre-fertilization, pre-birth and pre-weaning provisioning and protecting are done by females. Calves are precocial at birth. This means they able to swim immediately after emerging from their mother. Male fin whales become sexually mature at a body length of about 18.6 meters (61 feet) while females mature at a body length of 19.9 meters (65.3 feet). Physical maturity does not occur until the whales have reached their full length, after 22 to 25 years of age. The average length for a physically mature male is 18.9 meters (62 feet) and 20.1 meters (66 feet) for females.

Fin whale mother nurse their young for six to seven months after they are born. Since calves do not have the ability to suckle, like land mammals, mothers must spray the milk into the mouths of their babies by contracting the circular muscles at the base of the nipple sinus. Feeding takes place at eight to 10 minute intervals throughout the day. At weaning calves are usually 14 meters (46 feet) long. At that time they travel with their mothers to cold water feeding areas where they learn to feed for themselves independent of their mothers.

Endangered Fin Whales

Fin whales are classified as “Endangered” on the International Union for Conservation of Nature (IUCN) Red List and U.S. Endangered Species Act (ESA, U.S. Fish and Wildlife) and depleted under the Marine Mammal Protection Act (MMPA). 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.

Humans have utilized fin whales for food. Their parts have been sources of valuable materials. Historically, fin whales were hunted extensively for their oil and blubber, as well as their baleen. Aboriginal peoples have hunted them for centuries for of food, fuel, and building materials. Large-scale hunting efforts peaked in the 1950s, when nearly 10,000 whales were killed every year. [Source: Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW) /=]

Whaling is no longer a major threat to fin whales. Commercial whaling ended in the 1970s and 1980s, though some hunting continues today in Greenland through subsistence whaling allowances from the International Whaling Commission. Today, the biggest threat comes from vessel strikes. [Source: NOAA]

NOAA Fisheries and its partners are dedicated to conserving and rebuilding the fin whale population. They use innovative techniques to study, protect, and rescue these endangered whales and engage in developing regulations and management plans that foster healthy fisheries and reduce the risk of entanglements, create whale-safe shipping practices, and reduce ocean noise.

The International Whaling Commission has set a zero limit for fin whale catches in the North Pacific and southern hemisphere. The catch limit was passed in 1976 and continues be law today. Hunting stopped in the North Atlantic in 1990. There are some exceptions to the commission’s ruling. A limited number of whales are allowed to be caught and killed by aboriginal natives in Greenland. Commercial catches resumed in Iceland in 2006 and a Japanese fleet began catching fin whales for "scientific" purposes in 2005. /=\

Threats to Fin Whales

Threats to fin whales include entanglement in fishing gear, vessel strikes, lack of prey due to overfishing and ocean noise. Recently attention was brought to the large amount of plastic consumed by whales. The effect of this is still not lnown.[Source: NOAA, Prashanth Mahalingam and Maya Silberstein, Animal Diversity Web (ADW) /=]

Vessel Strikes: Inadvertent vessel strikes can injure or kill fin whales. The projected increase in ship traffic arising from the opening of trans-polar shipping routes (as arctic sea ice continues to decline) will increase the risk of vessel strike, and also increase ambient noise and pollution. Vessel strikes are a particularly a concern in the Mediterranean Sea where collisions have been a significant source of fin whale mortality. Between 2000 and 2004, five fatal collisions with vessels were recorded off the east coast of the United States.

Entanglement: Fin whales can become entangled in fishing gear, either swimming off with the gear attached or becoming anchored. They can become entangled in many different gear types, including traps, pots, or gillnets. Once entangled, whales may drag and swim with attached gear for long distances, ultimately resulting in fatigue, compromised feeding ability, or severe injury, which may lead to reduced reproductive success and death. Fishing gear kills fin whales. Entanglement results in at least one death per year. Fishing accidents have killed four fin whales in the years 2000 to 2004.

Ocean Noise: Underwater noise threatens whale populations, interrupting their normal behavior and driving them away from areas important to their survival. Increasing evidence suggests that exposure to intense underwater sound in some settings may cause some whales to strand and ultimately die. A study done on whale calls showed that human sound can prevent mating. Since the whales use low frequency sounds to call to females, human interruption through sound waves, such as military sonar and seismic surveys can disrupt the signal sent to the females. This potentially can result in mates not meeting and a reduction in birth rates in populations.

Plastic: Fin whales gulp down tons of food each day. Along with that they also ingest huge amounts of plastic or at least the ones of the U.S. West Coast do. Reuters reported: Researchers estimated the amount of microplastics ingested by three species of baleen whales — blue, fin and humpback — off the U.S. Pacific coast. Fin whales, according to the study, may swallow roughly about 6 million microplastic pieces, or up to 26 kilograms (57 pounds) of plastic. Much of the plastic is found in krill, which passes it up the food chain. Less is found in fish. Fin whales consume lots of krill. [Source: Will Dunham, Reuters, November 2, 2022]

Fin Whales Make a Comeback in Antarctic Waters

After being driven to the brink of extinction, fin whales have made an impressive return to their ancestral feeding grounds around the Antarctic Peninsula. Yale Environment 360, reported: From 1904 to 1976, when industrial whaling took place in the Southern Ocean, whalers killed an estimated 700,000 fin whales, reducing their population to around 1 percent of its previous size. The whales all but disappeared from the Southern Ocean. In 1982, the International Whaling Commissions voted to ban commercial whaling, and in recent years, scientists have seen fin whales starting to make a comeback. [Source: Yale Environment 360, July 9, 2022]

Scientists at the University of Hamburg traveled to the Antarctic Peninsula in 2018 and 2019 to track fin whales using aerial surveys. They counted 100 groups of one to four fin whales, as well as several larger groups, including one near Elephant Island comprising 150 whales. Their findings were published in the journal Scientific Reports.

“I’d never seen so many whales in one place before and was absolutely fascinated watching these massive groups feed,” said Bettina Meyer, a biologist at the University of Hamburg and coauthor of the study, said in a statement. “When the whale population grows, the animals recycle more nutrients, increasing the productivity of the Southern Ocean,” Meyer said. “This boosts the growth of algae, which for their part absorb carbon dioxide from the atmosphere through photosynthesis, reducing the atmospheric carbon dioxide concentration.”

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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