Fin whale
click to enlarge

Balaenoptera physalus

Names

Azores : "Finbeque" - POR : Baleia comum - ITA : Balenottera comune - SPAIN : Ballena boba - GB : Fin whale - GER: Finnwall - NEDER : Gewone vinvis - SWEEDS : Sillval - NOORS : Finnhval - DEENS : Finhval - JAP : Nagasu kujira - NEDER : Blauwe vinvis

Biology

The fin whale is the second largest species in the world. On average females measure around 19 m although they can reach lengths of 24 m, and weigh up to 80 tons. The males are smaller and have a maximum size of 21 m long. Their body coloration is dark gray and their ventral region is white. On the head the coloration is markedly asymmetric. The lower right jaw and the frontal plates are white, while the lower left jaw and the left plates are light gray. The upper jaw has 260 to 480 pairs of baleen plates. They have 50 to 100 ventral grooves in the throat, extending at least to the navel. They feed mainly on small fish and cephalopods. Females can bear a single calf every 3 or 4 years. Gestation lasts for about 1 year and lactation takes at least 6 months. Newborns measure 6 m in length and weigh 2 to 3 tons. This species emits several types of sounds with frequencies that range from 0.01 to 28 kHz.

Observation

This species is not very common in the Azores. We found them for only 3 % of the time on our field trips, despite the fact that this species should be easy to identify because of their characteristically high and sonorous blow (4 to 6 m high). The fin whales that the team of Espaço Talassa found were small groups of 4 to 5 individuals that always followed the same route, probably while in migration. We were able to observe them feeding on horse mackerel, and they did not seem much disturbed by our presence. They are excellent swimmers and during migrations they travel at an average speed of 8 to 10 knots in a constant direction, breathing 3 to 4 times before diving for 2 to 3 minutes. They can dive to a depth of up to 250 m for about 15 minutes. Before making a deep dive, they arch their backs deeply but they do not lift the tail above the water as other species do. The fin whale can be confused with the Sei whale, the Minke whale or with the Blue whale. The best way to identify this species is to recognise the asymmetric pigmentation in the lower lips and plates.

Cetaceans in the Azores