Fin Whale Balaenoptera physalus

Fin whales are the second largest species of whale after blue whales. The two species are closely related, but fin whales have more pointed heads and are more streamlined than their giant cousins and unlike them they have various patterns of lighter shadings on their backs .  Also called ‘finback’ or ‘razorback’ whales because of the pronounced ridge that runs from their dorsal fin to their tail, the species was heavily hunted throughout the industrial whaling era.  With a predominantly open water/offshore distribution, fin whales are not so easily observed throughout most of their range, other than in the Mediterranean, where they are one of the most regularly observed whale species.  Sadly the Mediterranean population is also threatened by high levels of vessel traffic, among other things, and is considered vulnerable to extinction.

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Not to be confused with:

From a distance fin whales could be confused with other rorqual whales like blue, sei or Bryde’s whales. But once seen at close range the distinct chevrons, blazes, and white lower jaw make them easy to distinguish.

Distribution

Fin whales are widely distributed in colder offshore waters.  They are rarely observed in the tropics, with the exception of areas where there is regular up welling of cold water, such as off the coast of Peru¹.  Despite having been commercially important for whaling, the species’ distribution and seasonal movements are poorly understood. While most populations are thought to show seasonal shifts toward the poles for feeding in the summer and toward the subtropics for calving and mating in the winter, other populations, such as those in the Gulf of California, the East China Sea off of Japan, and the Mediterranean Sea^2,3 appear to be resident year-round.

Fin whales are native to the following countries or territories: Algeria; Angola; Antarctica; Argentina; Australia; Belgium; Bermuda; Bouvet Island; Brazil; Canada; Cape Verde; Chile; China; Congo; Congo, The Democratic Republic of the; Croatia; Cyprus; Denmark; Ecuador;  Falkland Islands (Malvinas); Faroe Islands; Fiji; France; French Southern Territories (Kerguelen); Gabon; Germany; Gibraltar; Greece; Greenland; Heard Island and McDonald Islands; Iceland; Indonesia; Iran, Islamic Republic of; Iraq; Ireland; Isle of Man; Israel; Italy; Japan; Korea, Democratic People's Republic of; Korea, Republic of; Lebanon; Libya; Madagascar; Malaysia; Malta; Mauritius (Rodrigues); Mexico; Monaco; Morocco; Mozambique; Namibia;Netherlands; New Caledonia; New Zealand; Norway; Pakistan; Peru; Philippines; Portugal; Réunion; Russian Federation; Saint Helena, Ascension and Tristan da Cunha (Tristan da Cunha); Saint Pierre and Miquelon; Saudi Arabia; Seychelles (Aldabra); Slovenia;South Africa; South Georgia and the South Sandwich Islands; Spain; Sri Lanka; Sweden; Syrian Arab Republic; Tunisia; Turkey; United Arab Emirates; United Kingdom; United States; Venezuela, Bolivarian Republic of

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Biology and Ecology

Feeding

Like other species of baleen whale, fin whales tend to be fairly flexible in their diet in the Northern Hemisphere, where they feed on a variety of small schooling fish such as capelin, herring, mackerel and whiting, as well as planktonic crustaceans like krill and copepods.  In the Southern Hemisphere, fin whales appear to feed almost exclusively on krill, bringing them into competition with the other species of baleen whale that visit the Antarctic to feed⁴.   Fin whales are predominantly lunge feeders  often roling on their sides with gaping mouths and extended throat pleats as they gulp in schools of small fish or swarms of crustaceans, which they then filter through their baleen.⁵

Social Structure Reproduction and growth

Fin whale seasonal movements are less preditable and less well defined than many other species of baleen whales that demonstrate very clear migration patterns between known summer feeding grounds and winter breeding grounds.  However, fin whale mating does follow a seasonal pattern, with Northern Hemisphere populatoins mating in December-February and Southern Hemisphere populations between May and July.  Calves are born after roughly 11 months of gestation.  The only stable social bond between individual fin whales is that between the mother and the calf, until the calf is weaned at 6-7 months.  Females usually produce one calf every 2-3 years.

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Threats and conservation status

Natural Predators

Killer whales are the only known natural predator of fin whales, but due to fin whales’ large adult size, only calves are likely to be truly vulnerable to predation.

Human induced threats

Since the cessation of commercial whaling, one of the most pervasive threats to fin whales is thought to be ship strikes^6-8.  One study found that a third of all fin whale strandings appeared to involve ship strike⁷, and this risk is considered particularly high for the vulnerable subpopulation of fin whales in the Mediterranean⁹.  Fin whales in the Mediterranean are also exposed to high levels of underwater noise and the risk of entanglement in fishing gear².   These whales, and those resident in the Gulf of California may also be particularly vulnerable to climate change that affects prey distribution in their year-round habitat⁶.   There are also concerns about the accumulation of microplastics and other contaminants in both of these resident fin whale populations¹⁰.

 Conservation status

 Heavily hunted during the industrial whaling period in the first half of the 20^th century, fin whales were severely depleted.  Globally the species is considered Vulnerable on the IUCN Red List of Threatened species because the remaining population is considered to be such a small fraction of what it was before modern whaling.  The Mediterranean subpopulation is also considered Vulnerable.   The species is listed under Appendix I of the Convention on Migratory Species(CMS).  Global population estimates are difficult to obtain due to the species’ dispersal over deep open oceans that are difficult to survey with traditional methods.

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Fin whales and whale watching

With the exception of the Mediterranean Sea, particularly off the coasts of France and Italy, fin whales are not often the primary target of whale watching tours, but they can be viewed on whale-watching tours in some of the prime whale watching areas where the species occurs, such as British Columbia¹¹, the Gulf of Maine/Stellwagen Bank¹², and  Alaska¹³.

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