Sei whale (Balaenoptera borealis)
|Researched by||Morvan Barnes||Refereed by||Admin|
|Other common names||-||Synonyms||-|
Recorded distribution in Britain and IrelandOccasionally seen off the coasts of north and north-west Scotland and west Ireland but one sighting also puts it off the west coast of devon.
HabitatThe sei whale is an open ocean whale, not often seen near the coast. It can be found at the surface or diving down to a few hundred metres.
- Up to 16 m in length.
- Uniform dark blue-grey dorsal and lateral colouration; white underneath.
- Thick tail base.
- Tall, steep dorsal fin on posterior third of the back.
- Between 32-62 ventral pleats ending before the navel.
- Longest ventral pleat ends past flippers.
At a glance, the sei whale can be easily be confused with the minke whale Balaenoptera acutorostrata but can be distinguished by having dark coloured flippers and a uniform blue-grey upper body. The sei whale can also be differentiated from Bryde's whale Balaenoptera edeni by having only a single prominent ridge on the rostrum.
Sei whales usually congregate in small groups of up to 5 individuals, although in feeding areas up to 30 have been seen together. It seldom breeches, and when diving, it does not show the tail flukes. It can remain submerged for up to 20 minutes (Kinze, 2002).
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South East Wales Biodiversity Records Centre, 2018. SEWBReC Mammals (South East Wales). Occurrence dataset: https://doi.org/10.15468/atlxpp accessed via GBIF.org on 2018-10-02.
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Whale and Dolphin Conservation, 2018. WDC Shorewatch Sightings. Occurrence dataset: https://doi.org/10.15468/9vuieb accessed via GBIF.org on 2018-10-02.
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Last Updated: 24/06/2008