Fin Whale (Balaenoptera physalus)

	Fin Whale (Balaenoptera physalus) Photo: NMFS Southwest Fisheries Science Center

	Did You Know? · Individual fin whales can be identified by the pattern of chevrons and streaks of lighter coloration on their back, in addition to the size and shape of their dorsal fin. · The asymmetrical coloration pattern on the head of fin whales is reversed on their tongue. · Fin whales sometimes mate with blue whales and hybrids have been documented.

Status
ESA Endangered - throughout its range
MMPA Depleted - throughout its range

Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Balaenopteridae
Genus: Balaenoptera
Species: physalus

Species Description
Fin whales are the second-largest species of whale, with a maximum length of about 75 ft (22 m) in the Northern Hemisphere, and 85 ft (26 m) in the Southern Hemisphere. Fin whales show mild sexual "dimorphism", with females measuring longer than males by 5-10%. Adults can weigh between 80,000-160,000 lbs (40-80 tons).

Fin whales have a sleek, streamlined body with a V-shaped head. They have a tall, "falcate" dorsal fin, located about two-thirds of the way back on the body, that rises at a shallow angle from the animal's back. The species has a distinctive coloration pattern: the back and sides of the body are black or dark brownish-gray, and the ventral surface is white. The unique, asymmetrical head color is dark on the left side of the lower jaw, and white on the right side. Many individuals have several light-gray, V-shaped "chevrons" behind their head, and the underside of the tail flukes is white with a gray border.

Fin whales can be found in social groups of 2-7 whales and in the North Atlantic are often seen feeding in large groups that include humpback whales, minke whales, and Atlantic white-sided dolphins (Jefferson et al. 2008). Fin whales are large, fast swimmers and the killer whale (Orcinus orca) is their only non-human predator.

During the summer, fin whales feed on krill, small schooling fish (e.g., herring, capelin, and sand lance), and squid by lunging into schools of prey with their mouth open, using their 50-100 accordion-like throat pleats to gulp large amounts of food and water. They then filter the food particles from the water using the 260-480 "baleen" plates on each side of the mouth. Fin whales fast in the winter while they migrate to warmer waters.

Little is known about the social and mating systems of fin whales. Similar to other baleen whales, long-term bonds between individuals are rare. Males become sexually mature at 6-10 years of age; females at 7-12 years of age. Physical maturity is attained at approximately 25 years for both sexes. After 11-12 months of gestation, females give birth to a single calf in tropical and subtropical areas during midwinter. Newborn calves are approximately 18 ft (6 m) long, and weigh 4,000-6,000 lb (2 tons).

Fin whales can live 80-90 years. The age of large whales in family Balaenopteridae can be estimated by counting the layers present in waxy ear plugs, which are formed in the auditory canal (Hohn 2002).

Habitat
Fin whales are found in deep, offshore waters of all major oceans, primarily in temperate to polar latitudes, and less commonly in the tropics. They occur year-round in a wide range of latitudes and longitudes, but the density of individuals in any one area changes seasonally.

Distribution
There are two named subspecies of fin whale:

B. physalus physalus in the North Atlantic
B. physalus quoyi in the Southern Ocean

There is also a population of fin whales in the North Pacific, which most experts consider a separate, unnamed subspecies. These populations rarely mix, if at all, and there are geographical stocks within these ocean basins. Fin whales are migratory, moving seasonally into and out of high-latitude feeding areas, but the overall migration pattern is complex, and specific routes have not been documented. However, acoustic recordings from passive-listening hydrophone arrays indicate that a southward "flow pattern" occurs in the fall from the Labrador-Newfoundland region, past Bermuda, and into the West Indies (Clark 1995). 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
(Balaenoptera physalus)
Photo: NOAA

Population Trends
Although reliable and recent estimates of fin whale abundance are available for large portions of the North Atlantic Ocean, this is not the case for most of the North Pacific Ocean nor for the Southern Oceans. The present status of populations in these ocean basins relative to their pre-whaling population size is uncertain.

For management purposes, fin whales in U.S. waters have been divided into four stocks:

Hawaii
California/Oregon/Washington
Alaska (Northeast Pacific)
Western North Atlantic

Reliable estimates of current and historical abundance of fin whales in the entire northeast Pacific are currently not available. While reliable estimates of the minimum population size and population trends are available for a portion of this area, much of the North Pacific range has not been surveyed.

A 2002 shipboard line-transect survey of the entire Hawaiian Islands EEZ resulted in an abundance estimate of 174 fin whales (Barlow 2003). As of the 2004 Hawaii stock assessment report, this was the best available abundance estimate for this stock.

The California/Oregon/Washington stock was estimated at 3,279 fin whales based on ship surveys in summer/autumn of 1996 (Barlow and Taylor 2001) and 2001 (Barlow 2003). The 2003 stock assessment report lists the minimum population of this stock at approximately 2,541 animals.

Although the full range of the Alaska (Northeast Pacific) stock of fin whales has not been surveyed, a rough estimate of the size of the population west of the Kenai Peninsula is 5,700 (as of the 2007 stock assessment report). This is a minimum estimate for the entire Alaska stock because it was estimated from surveys which covered only a small portion of the range of this stock.

The minimum population estimate for the Western North Atlantic fin whale stock is 1,678. There are insufficient data to determine trends for this population.

Threats
Commercial whaling for this species ended in the North Pacific Ocean in 1976, in the Southern Ocean in 1976-77, and in the North Atlantic Ocean in 1987. Fin whales are still hunted in Greenland and subject to catch limits under the International Whaling Commission's "aboriginal subsistence whaling" scheme.

Other current threats are collisions with vessels, entanglement in fishing gear, reduced prey abundance due to overfishing, habitat degradation, disturbance from low-frequency noise and the possibility that illegal whaling or resumed legal whaling will cause removals at biologically unsustainable rates. Of all species of large whales, fin whales are most often reported as hit by vessels (Jensen and Silber, 2004 [pdf]). Schooling fish constitute a large proportion of the fin whale's diet in many areas of the North Atlantic, so trends in fish populations, whether driven by fishery operations, human-caused environmental deterioration, or natural processes, may strongly affect the size and distribution of fin whale populations.

Conservation Efforts
The Atlantic Large Whale Take Reduction Team was established to develop a plan to reduce the incidental serious injury and mortality of fin whales, right whales, humpback whales, and minke whales in the South Atlantic shark gillnet fishery, the Gulf of Maine and Mid-Atlantic lobster trap/pot fishery, the Mid-Atlantic gillnet fishery, and the Gulf of Maine sink gillnet fishery. For more about the Atlantic Large Whale TRT, please visit the ALWTRT page on our Northeast Regional Office website.

The 2007 IUCN Red List of Threatened Species lists fin whales as "endangered."

Regulatory Overview
Within the U.S., the fin whale is listed as endangered throughout its range under the Endangered Species Act of 1973 and is listed as "depleted" throughout its range under the Marine Mammal Protection Act of 1972.

Key Documents
(All documents are in PDF format.)

Title	Federal Register	Date
5-Year Status Review Initiated	72 FR 2649	01/22/2007
Draft Recovery Plan	71 FR 38385	07/06/2006
ESA Listing Rule	35 FR 18319	12/02/1970
Stock Assessment Reports	n/a	various

More Information

References:

Barlow, J. 2003. Cetacean abundance in Hawaiian waters during summer/fall 2002. Admin. Rep. LJ-03-13. Southwest Fisheries Science Center, National Marine Fisheries Service, 8604 La Jolla Shores Drive, La Jolla, CA 92037.
Clark, C.W. 1995. Application of US Navy underwater hydrophone arrays for scientific research on whales. Rep. int. Whal. Commn 45:210B212.
Hohn, A.A. 2002. Age Estimation. pp. 6-13. In: W.F. Perrin, B. Würsig, & H. Thewissen (eds.) Encyclopedia of Marine Mammals. Academic Press, San Diego, CA.
Jefferson, T.A., M.A. Webber, and R.L. Pitman. (2008). Marine Mammals of the World, A Comprehensive Guide to their Identification. Amsterdam, Elsevier. Pp. 47-50.
Jensen, A.S. and G.K. Silber. 2003. Large Whale Ship Strike Database. U.S. Department of Commerce, NOAA Technical Memorandum. NMFS-OPR-25, 37 pp.