by: Dagmar Fertl
The name is from the Latin borealis for "northern". The common name comes from the Norwegian word seje for "pollack", the fish, with which they are often found off northern Norway.
Sei whales can be confused with fin and Bryde's whales (in particular, the latter). The dorsal fin rises at a steep angle from the back. Sei whales have only one prominent head ridge, as well as a slightly arched rostrum with a downturned tip. The sei whale is dark gray with a lighter underside. The back is often marked with scars. Like other rorquals, throat pleats are present, though they don't extend all the way to the navel as in other species. This whale has a blow that can reach three meters in height.
Adults are up to 18 m in length and weigh as much as 30 tons.
They can be found anywhere along all coastlines of Africa, with the exception of far into the Mediterranean Sea. In winter, they are present off the west and east coasts of South Africa. Sei whales found off northwest Africa probably move towards Norway and more northern waters in the summer.
Sei whales occur most often in groups of 2-5 individuals. These whales are possibly the fastest swimming cetacean. Unlike other rorquals, sei whales skim their food (instead of lunging), feeding on copepods and other small prey.
In the past, these whales were hunted, but have since begun to recover from exploitation in most areas.
Vulnerable.
Gambell, R. 1985. Sei whale Balaenoptera borealis (Lesson, 1828). In: Handbook of marine mammals, volume 3: the sirenians and baleen whales (S.H. Ridgway and R. Harrison, eds). Academic Press, London. Pp 155-170.
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