Bp903


From the bulletin Portrait de baleines, September 7, 2018

Bp903 has two long, pronounced scars on its left chevron that make it easy to recognize. Its dorsal fin does not show any notches, but it does have a well defined sickle shape. Its chevron also shows considerable detail on the right side. This individual of undetermined sex was first observed in 2007. Seven years passed before it was seen again in the Marine Park. Since 2015, it has visited the St. Lawrence Estuary every year. This year, it was first photo-identified in August. Bp903 is now part of the new 2018 catalogue of large rorquals in the Saguenay-St. Lawrence Marine Park. This new edition includes data updated in 2017.

The fin whale often plays second fiddle when it comes to whale-watching. It is perceived as less spectacular and less showy than the blue whale or the humpback, as it rarely raises its tail when it dives. Compared to other whales, it often finishes runner-up. The fin whale is the second largest whale after the blue whale. It is also the second fastest, after the sei whale. When it surfaces, the fin whale shows only its back, which makes the rest of its body quite mysterious when viewed from outside the water. Underwater, its long, slim, hydrodynamic shape makes it look like a torpedo. It is more slender than other species. Its head makes up 20 to 25% of its body, i.e. a quarter of its total size, whereas in blue whales, the head accounts for 22 to 27% of the body. Like most baleen whales, a fin whale’s pectoral fins have 4 non-articulated fingers grouped in a single fin on each side. Only the shoulder joint is mobile. Its fins are relatively small and thin for a whale and measure only 8 to 10% of its total size, or two metres. In humpbacks, on the other hand, the pectoral fins measure about one-third of their total length, or about five metres. Five metres corresponds to the width of the caudal fin in fin whales. In blue whales, the caudal fin can measure up to 7 metres! The caudal fin of cetaceans is an extension of the spine, so it has no other bones, unlike fins. The only remains of cetaceans’ terrestrial ancestors are the two small pelvic bones located near their genital slits. These bones are floating and detached from the rest of the skeleton and their usefulness is still an enigma…