Balaenoptera physalus

Geographic Range

Fin whales, or fin-backed whales, are found in all major oceans and open seas. Some populations are migratory, moving into 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 meet at the equator at the same time during the year. Other populations are sedentary, staying in the same area throughout the year. Non-migratory populations are found in the Mediterranean Sea and the Gulf of California.

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.

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 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.

• Biogeographic Regions
• arctic ocean arctic ocean
  • native native
• indian ocean
  • native native
• atlantic ocean atlantic ocean
  • native native
• pacific ocean pacific ocean
  • native native
• mediterranean sea
  • native native

• Other Geographic Terms
• cosmopolitan cosmopolitan

Habitat

Fin whales inhabit the temperate and polar zones of all major oceans and open seas and, less commonly, in tropical oceans and seas. They tend to live in coastal and shelf waters but never in water less than 200 meters deep.

• Habitat Regions
• temperate temperate
• tropical tropical
• polar polar
• saltwater or marine saltwater or marine

• Aquatic Biomes
• pelagic pelagic
• coastal coastal

Physical Description

Fin whales are the second largest mammals, after blue whales . They grow to 20 meters in length and weigh approximately 70,000 kilograms. Size varies geographically: southern hemisphere whales are roughly 20 meters long, while northern and Arctic fin whales reach up to 25 meters in length. Sexual dimorphism in fin whales is limited, with males and females reaching roughly the same size and weight as adults. It is generally easy to distinguish fin whales by their long, lean bodies, their brown-grey dorsal surface, and deep white undersides. 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 cm 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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

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.

• Mating System
• monogamous monogamous

Both mating and calving occur in the late fall or winter when fin whales inhabit warmer waters. Each female gives birth every 2 to 3 years, birthing one calf per pregnancy. Although there have been reports of fin whales giving birth to multiple offspring, it is rare and those offspring rarely survive. The gestation period is 11 to 11.5 months. The mother then undergoes a resting period of 5 or 6 months before mating again. This resting period may extend to a year if the female fails to conceive during the mating period.

Fin whale calves are born at an average length of 6 meters and weighing 3,500 to 3,600 kilograms. Calves are precocial at birth, able to swim immediately after. The age of sexual maturity ranges in from 4 to 8 years. Male fin whales become sexually mature at a body length of about 18.6 meters while females mature at a body length of 19.9 meters. 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 m and 20.1 m for females.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous

The mother nurses the infant for 6 to 7 months after it is born. Since the calf does not have the ability to suckle, like land mammals, the mother must spray the milk into the mouth of the baby by contracting the circular muscles at the base of the nipple sinus. Feeding takes place at 8 to 10 minute intervals throughout the day. At weaning the calf is usually 14 meters long, it then travels with its mother to a polar feeding area where it learns to feed itself independent of its mother.

• Parental Investment
• precocial precocial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

The typical lifespan of a fin whale is roughly 75 years but some there are reports of fin whales that have lived in excess of 100 years.

Behavior

Fin whales are among the most sociable species of whales, they often congregate in family groups of between 6 and 10 members. Occasionally fin whales form groups of nearly 250 individuals near feeding grounds or during migration periods. Fin whales are highly migratory; in spring and early summer they usually reside in colder feeding waters, in fall and winter they return to warmer waters to mate. Fin whales have long been noted for their extreme speed and are one of the fastest marine mammals, with a cruising speed of nearly 23 mph and a “sprinting” speed of nearly 25 mph. Fin whales can dive up to depths of roughly 250 m and stay underwater for nearly 15 minutes. In addition, male fin whales often make extremely low frequency sounds that are among the lowest sounds made by any animal.

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• nocturnal nocturnal
• motile motile
• migratory migratory
• social social

Home Range

Home range sizes have not been established. Fin whales migrate over long distances throughout the year.

Communication and Perception

Fin whales, like blue whales, communicate through vocalizations. 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 1 and 2 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.

• Communication Channels
• acoustic acoustic

• Other Communication Modes
• choruses choruses

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• ultrasound ultrasound
• chemical chemical

Food Habits

Fin whales primarily feed on plankton-sized animals including crustaceans, fish, and squid. As filter feeders they passively consume food by filtering prey out of the water that they swim through. Fin whales occasionally swim around schools of fish to condense the school so that they increase their catch per dive.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods
  • eats other marine invertebrates
• planktivore planktivore

• Animal Foods
• fish
• aquatic crustaceans
• other marine invertebrates
• zooplankton zooplankton

• Plant Foods
• phytoplankton phytoplankton

• Foraging Behavior
• filter-feeding filter-feeding

Predation

Adult fin whales have no natural predators. Populations have been heavily exploited by humans who nearly hunted them to extinction in the early part of the 20th century. Hunting exceeded nearly 10,000 whales per year in the 1950’s. Young fin whales may be targeted by large predators, such as killer whales , although fin whales groups are likely to be successful in defending their young.

Ecosystem Roles

Fin whales have little pressure exerted on them by predatory animals and thus their main contribution to the general ecosystem is to consume large amounts of plankton. Their carcasses also support communities of benthic animals as they fall to the ocean floor and are consumed. As do other large whales, fin whales also host large communities of parasites, such as barnacles, lice, and worms.

Economic Importance for Humans: Positive

Historically, fin whales were hunted extensively for their oil and blubber, as well as their baleen. Aboriginal peoples have hunted fin whales for centuries and all parts of the whale were integral in their lives as a source of food, fuel, and building materials. Large-scale hunting efforts peaked in the 1950’s, as nearly 10,000 whales were killed every year.

• Positive Impacts
• food food
• body parts are source of valuable material
• source of medicine or drug source of medicine or drug
• research and education

Economic Importance for Humans: Negative

Fin whales have no negative economic effects on humans.

Conservation Status

Overhunting is responsible for low population numbers of fin whales currently. With the invention and use of modern whaling technology, fin whale populations were depleted due to hunting. In addition, fin whales are injured or killed in vessel collisions. This is especially true in the Mediterranean Sea where collisions are a significant source of fin whale mortality. Between 2000 and 2004, 5 fatal collisions with vessels were recorded off the east coast of the United States. Fishing gear also kills fin whales; entanglement results in at least one death per year. Fishing accidents have killed 4 fin whales in the years 2000 to 2004. Finally, a study done on whale calls shows 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.

In order to help populations of fin whales recover worldwide, 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 limitation, 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.

Additional Links

Encyclopedia of Life

Contributors

Prashanth Mahalingam (author), University of Michigan-Ann Arbor, Maya Silberstein (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor, Tanya Dewey (editor), Animal Diversity Web.

References

Croll, D., C. Clark, A. Acevedo, B. Tershy, S. Flores, J. Gedamke, J. Urban. 2002. Only Male Fin Whales Sing Loud Songs. Nature , 117: 809. Accessed April 09, 209 at http://polymer.bu.edu/hes/articles/aabmsss02.pdf .

Gambell, R. 1985. Fin Whale, Balaenoptera physalus. Pp. 171-192 in Handbook of Marine Mammals , Vol. 3, first Edition. San Diego, CA: Academic Press Inc..

Jefferson, T., S. Leatherwood, M. Webber. 1994. Marine Mammals of the World . Rome, Italy: Food and Agriculture Organization of the United Nations.

McDonlad, M., J. Hildebrand, S. Webb. 1995. Blue and Fin Whales Observed on Seafloor Array in the Northeast Pacific. Journal of the Acoustical Society of America , 98/2: 712-721.

Nowak, R. 1991. Balaenopteridae: Roquals. Pp. 969-1044 in Walker's Mammals of the World , Vol. 2, Fifth Edition. Baltimore and London: The John Hopkins University Press.

Reeves, R., B. Stewart, P. Clapham, J. Powell. 2002. Sea Mammals of the World . London: A&C Black.

Sokolov, V., V. Arsen'ev. 1984. Baleen Whales . Moscow: Nauka Publishers.

Tinker, S. 1988. Whales Of The World . Honolulu, Hawaii: Bess Press Inc..

2008. "Balaenoptera physalus" (On-line). ICUN 2008 Red List. Accessed April 02, 2009 at http://www.iucnredlist.org/details/2478 .

2006. "Finback Whales, Bioacoustics Research Program" (On-line). Cornell Lab of Ornithology. Accessed April 09, 209 at http://www.birds.cornell.edu/brp/listen-to-project-sounds/fin-whales .