Biology:Powan
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] FishBase and the IUCN continue to recognize the Scottish powan as a distinct species, Coregonus clupeoides.[1][8]
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
- ↑ 1.0 1.1 1.2 Cite error: Invalid
<ref>tag; no text was provided for refs namediucnredlist - ↑ 2.0 2.1 "Vendace and Powan: the Coregonids". http://www.snh.gov.uk/about-scotlands-nature/species/fish/freshwater-fish/vendace-powan/.
- ↑ "Powan project to ensure survival of rare UK fish species". 9 February 2010. http://www.fishnewseu.com/latest-news/scottish/2800.html.
- ↑ "Hundreds of rare powan fish to be released into Loch Lomond in conservation effort". news.scotsman.com. 23 March 2010. http://news.scotsman.com/nature/Hundreds-of-rare-powan-fish.6172052.jp.
- ↑ Winfield, I,J.; Fletcher, J.M. (2008). Hydroacoustic assessment of the introduced powan populations of Carron Valley Reservoir and Loch Sloy. Final Report (Technical report). NERC/Centre for Ecology and Hydrology. LA/C03407/2.
{{cite tech report}}: CS1 maint: multiple names: authors list (link) - ↑ Etheridge E.C (2009). Aspects of the conservation biology of Coregonus lavaretus in Britain (PDF) (PhD thesis). University of Glasgow.
- ↑ Etheridge, E.C.; C. E. Adams; C. W. Bean; N. C. Durie; A. R. D. Gowans; C. Harrod; A. A. Lyle; P. S. Maitland et al. (2012). "Are phenotypic traits useful for differentiating among a priori Coregonus taxa?". Journal of Fish Biology 80 (2): 387–407. doi:10.1111/j.1095-8649.2011.03189.x. PMID 22268437. Bibcode: 2012JFBio..80..387E.
- ↑ Froese, Rainer and Pauly, Daniel, eds. (2010). "Coregonus clupeoides" in FishBase. March 2010 version.
- ↑ Maitland, Peter S. (1969). "The Reproduction and Fecundity of the Powan Coregonus clupeoides Lacepède in Loch Lomond, Scotland". Proc. Roy. Soc. Edinb. B 70 (3): 233–264. https://books.google.com/books?id=a2f83FDCXzUC&pg=PA374.
External links
Template:Whitefish Template:Endemic biota of Scotland Wikidata ☰ Q2705955 entry
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