Fin Whale(Balaenoptera physalus)
- to a maximum length of 22 metres
- dark gray to brownish black on back and sides
- no mottling like the blue whale
- undersides are white
- right lower lip is white and the left lower lip is dark – this asymmetrical head colouration is a diagnostic feature that can be reliably used to differentiate fin whales from other species of large whales
- 2/3 metre in height, sickle shaped and curving towards the back
- is seen shortly after the blow
- narrow, cone shaped, up to 6 metres in height
- slightly concaved bottom edge with distinct notch in the middle
- fin whales rarely lift the tail fluke prior to a deep dive
- unlike blue or sei whales, fin whales occasionally leap clear of the water
Group size / social behaviour
- head is V-shaped
Can be confused with
- blue and sei whales – especially from a distance due to the extremely tall blows of all of these species. However, the dark coloration and the larger dorsal fin that is seen shortly after the blow distinguishes fin whales from blue whales, and the distinctive white coloration on the right lower jaw distinguishes from sei whales, which are also very rare in BC waters.
Fin whales are a cosmopolitan species, found throughout the world’s oceans in coastal and pelagic waters. They seem to be most abundant in polar and temperate areas. In Canada there is both an Atlantic and Pacific population of fin whale. In British Columbia, fin whales are seen in summer and winter months, most commonly in offshore waters, Hecate Strait and Queen Charlotte Sound. It is still unclear how many different stocks of fin whales are in the north Pacific and if the fin whales found in BC are more closely associated with those found in Alaska, or those in the California/Washington/Oregon range.
Fin whales feed primarily on small invertebrates, schooling fish and squids. In the north Pacific 70% of their diet was found to be made of euphasiids, while another 25% were copepods. Fin whales are a rorqual, meaning they have a pleated throat. They are able to take in up to an incredible 70 tonnes of food-rich saltwater into their extended throat and then use their baleen to sieve out the food as they expel saltwater.
Little is known about the breeding behaviours and areas of the fin whale. It is believed that it happens in lower latitudes during the winter months, but as of yet, no breeding ‘grounds’ for fin whales have been found. It is possible that due to the long-distance communication fin whales are capable of, they may not need a specific geographical location in order to find breeding partners.
Both sexes are estimated to reach sexual maturity between 5-15 years of age and females appear to have a calf every 2-3 years. Their gestation is between 11-12 months, after which the calves are weaned at 6-7 months. Interestingly, hybridization between fin and blue whales is not uncommon. Hybridization can happen between either sex of either species, and it is yet unknown the reproductive capacity of these hybrids.
Fin whales appear to have a long lifespan between 50-100 years, with females growing slightly (5-10%) larger than males, though at a slower rate. Data on fin whale size and growth has mostly been compiled through whaling records. Fin whales were heavily targeted by coastal whaling in the Pacific northwest until the 1970s. Currently, fin whales are threatened by ship strikes. Fin whales are the most commonly struck whale world wide, though why this is the case is unclear. Speed may play a factor as vessels travelling over 14 knots have a much higher likelihood of fatally hitting cetaceans. Between 1999 and 2004, at least 6 fin whales were hit and killed around Canadian Pacific waters.
Status in Canada
The fin whale is designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
COSEWIC’s assessment of the Pacific population of the fin whale is as follows:
Currently sighted only infrequently on former whaling grounds off British Columbia. Coastal whaling took at least 7,600 animals from the population between 1905 and 1967, and thousands of additional animals were taken by pelagic whalers through the 1970s. Catch rates from coastal whaling stations declined precipitously off British Columbia in the 1960s. Based on the severe depletion and lack of sufficient time for recovery, it is inferred that present population is below 50% of its level, 60-90 years ago. Individuals continue to be at risk from ship strikes and entanglement in fishing gear.
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