Mammals
Sei Whale
Balaenoptera borealis · also called sei whales
Accelerating to nearly 50 kilometres per hour in a rare burst of speed, a sei whale demonstrates exactly why it evaded commercial whaling fleets for so much longer than its slower relatives, a speed advantage that only delayed, rather than prevented, its eventual decline.
Overview
The sei whale, Balaenoptera borealis, is the third-largest baleen whale species, native to open ocean waters across nearly every ocean in the world, from subpolar regions to warmer temperate waters. Its remarkable swimming speed, unusually fine baleen plates suited to smaller prey, and status as one of the last great whales targeted by commercial whaling make it one of the more physically distinctive and conservation-significant large whales found anywhere on Earth.
Too fast to catch, until it wasn’t
For decades, the sei whale’s impressive speed kept it relatively safe from commercial whaling fleets pursuing slower species, a temporary reprieve that ended once faster ships and depleted competitor populations made it a viable target in its own right.
Status
Endangered but increasing, having been significantly reduced by intensive 20th-century whaling before showing gradual recovery in several regions following international protection.
Sei Whale: common questions
How fast can a sei whale swim?
This species is capable of short bursts of speed approaching 50 kilometres per hour, making it one of the fastest whales in the ocean, a speed that historically made it a genuinely difficult target for whaling vessels until faster ships were developed.
Why was the sei whale hunted later than other great whales?
This species became a major target of commercial whaling later than many other great whales largely because its considerable speed made it difficult to hunt with earlier, slower whaling vessels, meaning it was pursued more heavily only once faster ships became available and other, slower whale populations had already been severely depleted.
How big is the sei whale compared to other baleen whales?
This species ranks as the third-largest baleen whale species, trailing only the blue whale and fin whale in overall size among filter-feeding whales, making it a genuinely massive animal despite being overshadowed in scale by its two larger relatives.
What does the sei whale eat?
This species has a relatively varied diet, feeding on copepods, krill, and small schooling fish depending on what is most abundant locally, filtered through unusually fine, closely spaced baleen plates well suited to capturing smaller prey items than some other large whales manage.