The Falkland Islands and South Atlantic
SEI WHALE Balaenoptera borealis

SEI WHALE Balaenoptera borealis


  • bones female sei Saunders


  • sei-whale-bones-Saunders-femal



Sei whales belong to the family Balaenopteridae or 'Rorqual' (Old Norse meaning 'grooved whale') whales, characterised by their sleek body form and pleated throat grooves that expand when the whales feed allowing them to take massive gulps of food and water. Their ventral pleats extend down the belly well forward of the umbilicus. They are the fastest of the great whales.

Seis are big, sleek and dark grey above with white undersides. The dorsal fin is large and falcate. A long ridge forms the midline on the top of the head. Baleen, 300-400 plates on either side, is black or dark grey with a white inner fringe. They have a tall columnar blow, do not raise their tail flukes when diving and hardly ever arch their back when commencing a deep dive.

Length: up 19.5m (64ft), females slightly longer than males.

Food is quite wide-ranging and includes small fish, squid, krill and planktonic crustaceans. It uses the gulping method for fish and krill, and skims for copepods.

Calves are born in winter, in warmer waters after a gestation of 11-12 months. At birth Sei whales measure up to 4.5m (15ft) They probably live for more than 50 years.

On West Falklands Sei whales are regularly sighted off Saunders Island, Carcass Island and in King George Bay. On the East Falklands they appear off Sea Lion Island, Cape Dolphin, MacBride Head, and in Berkeley Sound.

Their IUCN Conservation status is 'endangered’. The Falkland Islands Marine Mammals Ordinance 1992 protects all marine mammals in all waters from the coast to the edge of the economic exclusion zone.

Has anyone got any live Sei Whale photographs they could add please?!


 Sources include: Sea Mammals of the World-Randall R. Reeves, Brent S. Steware, Phillip J Clapham, James A Powell,Falkland Islands State of the Environment Report 2008 Otley H, Munro G, Clausen A, Ingham B. Falklands Conservation,A Field Guide to the Wildlife of The Falkland Islands and South Georgia - Ian J Strange,
Photographic credits: Sei bones, a stranded 3 year old female, Saunders Is, Biffo Tuson
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