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Cornish Red Data (2009)

The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.

Balaenoptera borealis - Sei Whale

Range & Status

The Sei Whale is distributed world-wide, but is only rarely found in polar or tropical waters. It is sometimes found in sub-tropical areas, but mostly in temperate waters, and is thought to migrate into warmer, lower latitudes for the winter. This species was heavily exploited by the whaling industry during the 1960s and early 1970s and the population has been severely depleted, probably even before gaining full protection from commercial whaling in the 1970s and 1980s. 14,295 Sei Whales were taken in the North Atlantic Ocean between 1885 and 1984 (Horwood, 1987). The extent to which stocks have recovered since then is uncertain, though the global mature population is estimated to have declined by about 80% over the last three generations (Reilly et al ., 2008b). It is generally considered rare in UK waters.


Two strandings were recorded in the region, in 1989 and 1991.


2000 (1).


Listed as Endangered. (Reilly et al. , 2008b. Balaenoptera borealis . In: IUCN 2008. 2008 IUCN Red List of Threatened Species. . Downloaded on 18 March 2009.) A UK Biodiversity Grouped Plan species.


I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.

The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.

Cornish Biodiversity Network. 2017.