Balaenoptera borealis - The Sei Whale

 

Pollock

The sei whale gets its common name from the Norwegian for pollock, a large whitefish which arrives in the waters around Norway at around the same time as the whales. Other than that, the sei whale has very little in common with the pollock. For one thing, they’re enormous. They reach lengths of up to 64 feet and weigh 28 tonnes. They are very fast swimmers, reaching speeds of 27 knots or 50 kmph. It is an endangered species with only 80 000 animals alive today and they are still hunted by the Japanese, who call itイワシクジラ(Iwashi Kujira) or ‘Sardine whale’. The American naturalist Roy Chapman Andrews compared it to the cheetah because it can sprint very quickly over short distances but soon gets tired out.

Bryde's Whale and Sei Whale

Their appearance is similar to that of other rorquals and they are often confused with fin whales and bryde’s whales. If you happen to spot any of these animals on your travels, you can identify them best by getting your head right up to their mouths and having a good look at their baleen plates, which are much finer than other whales (only 0.1mm).

Of course, getting close enough to inspect a whale’s baleen may present difficulties to the casual or inexperienced whale watcher, so other distinguishing features include its pigmentation pattern and colouring: sei whales are slightly bluer in colour than their smaller relatives bryde’s whales, which have three ridges on their heads where the sei whale has only one. The sei whale has symmetrical colouring whereas fin whales do not. They prefer to be out in the open ocean rather than off the coast, and they seldom breach. They don’t rise out of the water as they dive, like fin whales do; they just tend to sink down out of sight. So you’re not very likely to see a sei whale, but now you’ll be better equipped to identify one if you do. There's a useful video here on the identification of sei whales.

Cookie cutter shark's teeth

Notice white scars from cookie cutter shark bites

Another identifying feature is that there are often white scars left from attacks by the small but vicious cookie cutter shark, against which the whales have no defense. They just sink in their amazing teeth, rip off a chunk of flesh and leave!

Cookie cutter shark

In terms of  feeding, they eat more like right whales, skimming for food rather than lunging, but they are rorquals so they still stretch out like the others and its quite a thing to see. They like small food, such as krill and copepods, but will also eat sardines, mackerel and other small fish..

Feeding

We don’t know a lot about their voices but their songs tend to be long, very low pitched and very loud. The BBC once interviewed a former whaler called Roddy Morrison, who operated around South Georgia in the Southern Ocean. In the interview he said "When we killed the sei whales, they used to make a noise, like a crying noise. They seemed so friendly, and they'd come round and they'd make a noise, and when you hit them, they cried really. I didn't think it was really nice to do that. Everybody talked about it at the time I suppose, but it was money. At the end of the day that's what counted at the time. That's what we were there for."