Powan
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Salmoniformes
Family: Salmonidae
Genus: Coregonus
Species:
C. clupeoides
Binomial name
Coregonus clupeoides
(Lacépède, 1803)

The powan (Coregonus clupeoides) is a kind of freshwater whitefish endemic to two lochs in Scotland, Loch Lomond and Loch Eck.[1] It has been successfully introduced in two other sites, Loch Sloy and the Carron Valley Reservoir.[2]

Powan populations are relatively healthy,[1] but may have been negatively impacted by the introduced ruffe, which eats powan eggs and fry. As a conservation action, an attempt to establish populations in four additional lochs has been undertaken.[3][4]

The taxonomic status of the British whitefish populations, including powan, is a matter of debate. Currently the Scottish powan, along with the Welsh gwyniad known from a single lake, and four similar populations in England known as schelly, are generally considered belonging to the widespread Eurasian common whitefish (Coregonus lavaretus).[2][5] This accords with the close genetic similarity among these units,[6] and the absence of clear morphological differences between them.[7] The FishBase and IUCN continue to recognize the Scottish powan as a distinct species, Coregonus clupeoides.[8][1]

Ecology

This fish is benthopelagic, feeding on the lakebed on insect larvae and crustaceans. In Loch Lomond, this fish exhibits a pattern of daily migration to feeding sites and of seasonal migration to breeding grounds. Before the breeding season, the mature males begin to congregate in deep water near the spawning beds; these are shallow areas of gravel and pebbles washed by waves. In late December and January they move into the shallows where they are joined by the ripe females, and spawning is completed by early February, after which the fish disperse to other parts of the loch. The eggs are eaten by brown trout (Salmo trutta), common roach (Rutilus rutilus), other powan and Phryganea larvae, and the adult powan are heavily predated by the northern pike (Esox lucius) at breeding time.[9]

References

  1. 1 2 3 Freyhof, J. & Kottelat, M. (2008) Coregonus clupeoides. In:IUCN Red List of Threatened Species. Version 2010.1. (Accessed 17 April 2010)
  2. 1 2 Vendace and Powan: the Coregonids Dualchas Nàdair na h-Alba (Scottish Nature Heritage) (Accessed 17 April 2010)
  3. ↑ Powan project to ensure survival of rare UK fish species fishnewseu.com (9 February 2010)
  4. ↑ Hundreds of rare powan fish to be released into Loch Lomond in conservation effort news.scotsman.com (23 March 2010)
  5. ↑ Winfield, I,J., Fletcher, J.M. (2008) Hydroacoustic assessment of the introduced powan populations of Carron Valley Reservoir and Loch Sloy. Final Report. Natural Environment Research Council
  6. ↑ Etheridge E.C (2009) Aspects of the conservation biology of Coregonus lavaretus in Britain. University of Glasgow
  7. ↑ Etheridge, E.C.; C. E. Adams; C. W. Bean; N. C. Durie; A. R. D. Gowans; C. Harrod; A. A. Lyle; P. S. Maitland; and I. J. Winfield (2012). Are phenotypic traits useful for differentiating among a priori Coregonus taxa? Journal of Fish Biology 80: 387–407. doi:10.1111/j.1095-8649.2011.03189.x
  8. ↑ Froese, Rainer; Pauly, Daniel (eds.) (2010). "Coregonus clupeoides" in FishBase. March 2010 version.
  9. ↑ Maitland, Peter S. (1970). Sport Fishery Abstracts. Department of the Interior, U.S. Fish and Wildlife Service. p. 374.
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