Species Profiles: fin whale

Classification
Key Identification Features
Where and When Best Seen in Ireland
Field Identification
Species Similar in Appearance
Status and Distribution
Food and Feeding
Reproduction and Life Cycle
Conservation Issues

Class: Mammalia
Order: Cetecea
Suborder: Mysticeti
Family: Balaenopteridae
Genus: Balaenoptera

Species: physalus

Common names: Fin whale; Finback; Herring Hog.

Irish Names: Míol mór eiteach

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Maximum body length: Adult ? 22m (72ft), adult ? 24m (80ft)
Record length: 27m (88.5ft)
Average body length: Adult ? 19m (62ft), adult ? 20.5m (67ft)
Blow: Tall, robust 6m (20ft) column, visible at great distances on windless days
Head shape:V-shaped, top is flat, single prominent median/rostral ridge
Beak:Narrow pointed snout, without a downturn at tip (unlike sei whale)
Dorsal fin: Not diagnostic, as highly variable. Small (60cm), falcate, backwards sloping, angled <40deg, located ? along back and appears shortly after blow.
Colouration:Dark grey to brownish black on back and sides

Markings: Right lower lip including mouth cavity are whitish, but lips & baleen on left side are all dark.

This asymmetrical head pigmentation is diagnostic. Right anterior 20-30% baleen plates are yellowish/white. 2 chevrons originate behind blowhole and run aft forming broad V along back. Broad pale wash sweeps up from corner of jaw to behind blowhole.

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The Fin whale is the 2nd largest living animal on earth, second only to the blue whale and dwarfing the most abundant baleen whale in Irish waters, the minke, whose length rarely exceeds 30ft.
Even from great distances, in calm conditions their robust blow, reaching heights of 20ft, is clearly visible. Once this is seen, you can rule out the minke whale, whose blow is rarely observed. The long roll of its back follows the blow, before the dorsal fin breaks the surface, some moments later. This classic fin whale surface rules out the smaller 50-60ft sei whale, whose blow and dorsal fin tend to appear simultaneously. Cetacean authors, who have misidentified fin and sei whales, have learnt that dorsal fins alone show too much variability to be a reliable diagnostic feature.
In stark contrast to the often, solitary minke, fin whales are generally seen in groups of 3- 10 and this, combined with their shallow dive pattern when traveling can make them quite detectable. They may blow as many as 10 times at short 15-20 second intervals for a number of minutes before taking a deeper “terminal dive”, which may result in their being submerged for 5-8 minutes. So, even a small pod of whales may generate a lot of explosive “vapour spouts ” per minute. If watching from land, you should have little problem tracking their movements and once you get a feel for them you will be able to predict with some accuracy where and when they are next likely to surface.

Fin whales do not lift their tail flukes when diving and if “fluking” is observed it’s likely you are watching humpback whales. But do not assume that a breaching whale is also a humpback whale, as fin whales on occasion are known to breach clear of the water. As they are indifferent to boats you may get close enough to observe their unique asymmetric head colouration.

Video Clip [MPG Format 2MB]

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Fin whales are widely distributed throughout the world and are now relatively common in areas of the north-east Atlantic, despite being one of the most heavily hunted by whalers. It is thought that about 600 fin whale were taken by the Norwegian owned whaling station that operated from Co. Mayo between 1908-1922. The total fin whale population in the North Atlantic is between 35,000- 50,000. They are the most abundant baleen whale in the Bay of Biscay and the fact that they are observed throughout the year in the Mediterranean Sea and for much of the year along the south coast of Ireland, suggests they are not as committed to an annual migration as species like the Humpback whale.

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Max life expectancy: c90years,
Female sexual maturity:6-10 years at 18-19m (60-62ft)
Gestation period:12 months
Calving frequency: a single calf is born every 2-3 years
Calves born:Between December and April in NE Atlantic at 6m (20ft)
Calf weaned:Between 6-8 months of age

Male sexual maturity:6-10 years at length 17-18m (58-60ft)

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A brief review of Irish sightings reveals that the fin whale is the most commonly observed large baleen whale in our waters. Although preferring deeper waters along the continental shelf, they can move to within viewing range of our headlands when inshore feeding opportunities occur.

Since 1999 increased observer effort along our south coast suggest that West Cork’s headlands (between Roches Point and Galley Head) offer excellent whale watching potential in which the fin whale figures strongly. On 3 consecutive years since 1999 fin whales have been observed from June onwards with sightings peaking around November-December. These high encounter rates 6 months of the year suggest a discreet sedentary population along our south coast, who do not strictly adhere to a predictable annual north- south migration, but may instead migrate relatively short distances between inshore and offshore waters.
Although generally seen in smaller groups of 3-8, in June 2000 a feeding aggregation of >15 fin whales was observed off the Old Head of Kinsale. Co. Cork and a similar event witnessed the following year in late July 2001 when a min. group size of 16-20 was observed in the same area.

The majority of fin whale sightings come from Co. Cork, but this is likely to reflect the level of observer effort in the area. They are on occasion observed in the Celtic Sea and in offshore waters along the western seaboard. A team of scientists at Cornell University using American military tracking devices has recently suggested 300-500 fin whales pass through Irish waters each year.

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Most likely confused with sei and blue whales in Ireland, however the latter is so rarely observed that this should not be an issue.

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Fin whales have a varied diet, comprising fish species such as herring, mackerel, cod, sand lance, squid and capelin, but young whales may take small invertebrates like krill and copepods. A 15m (50ft) fin whale will require upwards of 800,000 calories per day, the equivalent of 0.8 metric tons of food

Surface observations indicate that fin whales attack their prey at speed, turning on their sides when their mouths are open, feeding with the right side down. There is speculation that the white colour of the head’s right side and lower right flank startles prey, herding them into a tighter area, making it easier for the whale to feed. It is also possible that the broken pattern may camouflage the whale from its prey. Once the prey is caught, the 260-480 baleen plates that hang from each side of their upper jaws, filter the prey from the water. The baleen (whale bone) is approx 70-90cm long & 20-30 cm wide.

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The biggest threat facing this species is the resumption of full- scale commercial whaling. The fin whale has historically borne the brunt of much of the whaling in both the northern and southern hemispheres. Also of concern is the depletion of fish stocks through poor management of commercial fisheries.

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