Gyrodactylus salaris

Gyrodactylus salaris , commonly known as salmon fluke , [1] is a tiny monogenean ectoparasite which lives on the body surface of freshwater fish. [2] This parasite-like parasite has been implicated in the Atlantic salmon populations in the Norwegian fjords . [3] It also parasitises other species, including rainbow trout . [4] G. salaris requires fresh water , [2] but can survive inbrackish water for up to 18 hours. [5]

The parasite is 0.5 mm (0.02 in) long, [2] and can not be seen with the naked eye, but it can be seen with a magnifying glass . [6] On its posterior end is a haptor , a specialized organ for attaching to the host fish, which has sixteen hooks around its edge. [2] The parasite is viviparous , that is, it produces live offspring. [7] The parasites give birth to live as they grow up, and they are even growing up in the neonates. [4]

Interactions with host fish

When feeding, the parasite attaches its anterior end to the fish with cephalic acorns. It is a pharynx through the mouth and a digestive solution with proteolytic enzymes which dissolves the salmon skin. Mucus and dissolved skin are then sucked into the gut. Attachment of many parasites can cause wide wounds, which causes secondary infections. [4]


G. salaris was first described in 1952, [8] after being removed from a Baltic strain [2] of Atlantic salmon kept at the Hölle Laboratory in Sweden, near to the river Indalsälv. [8] At the time, it was not possible to cause illness in the host fish. [8] The presence of G. salaris on fish became a World Organization for Animal Health notifiable disease in 1983. [8]

Catastrophic losses of Atlantic salmon occurred in Norway in the 1970s following the introduction of G. salaris . By 2001, the salmon populations of 41 Norwegian rivers had been virtually wiped out in this way. [4]

Historically, Gyrodactylus -infected rivers have been treated with the indiscriminate pesticide / rotenone piscicide . A newer method of treatment employs small volumes of aqueous aluminumand sulfuric acid in the river. A huge advantage of this method is its ability to kill parasites without harming the hosts. This new method has been shown in Batnfjordelva and Lærdalselva, two rivers in Norway . quote needed ]


  1. Jump up^ Minchin, Dan (7 January 2008). ” Gyrodactylus salaris ” (PDF) . DASIE: Delivering Alien Invasive Species Inventories for Europe . Retrieved 2017-11-05 .
  2. ^ Jump up to:e Cain, Kenneth D .; Polinski, Mark P. (2014). “Chapter 3. Infectious Diseases of Gyrodactylosis”. In Woo, Patrick TK; Bruno, David W. Diseases and disorders of finfish in cage culture (2nd ed.). CABI. pp. 95-96. ISBN  9781780642079 .
  3. Jump up^ C.Michael Hogan. 2011. Norwegian Sea . Encyclopedia of Earth. Eds. P.Saundry & CJCleveland. National Council for Science and the Environment. Washington DC
  4. ^ Jump up to:d “Notifiable diseases: Gyrodactylus salaris ” . Scottish Government. December 8, 2009 . Retrieved 2017-11-05 .
  5. Jump up^ Hopkins, CEC (2002). Introduced marine organisms in Norwegian waters, including Svalbard, Parasites and diseases. In Leppakoski, Erkki; Gollasch, Stephan; Olenin, Sergej. Invasive Aquatic Species of Europe. Distribution, Impacts and Management . Dordrecht: Springer Netherlands. pp. 251-252. ISBN  9789401599566 .
  6. Jump up^ “Do not spread parasitic salmon Gyrodactylus salaris ” (PDF) . Finnish Ministry of Agriculture and Forestry. Archived from the original (PDF) on August 30, 2005 . Retrieved 11 November 2010 .
  7. Jump up^ Shoemaker, Craig; Xu, De-Hai; LaFrentz, Benjamin; LaPatra, Scott (2015). “Monogenetic trematodes”. In Lee, Cheng-Sheng; Lim, Chhorn; Gatlin, Delbert M. III; Webster, Carl D. Dietary Nutrients, Additives, and Fish Health . Wiley-Blackwell. p. 16. ISBN  978-0-470-96288-6 .
  8. ^ Jump up to:d Harris, Phil D .; Bachmann, Lutz; Bakke, Tor A. (2011). “The parasites and pathogens of the Atlantic salmon: Lessons from Gyrodactylus salaris “. In Aas, Øystein; Klemetsen, Anders; Einum, Sigurd; Skurdal, Jostein. Atlantic Salmon Ecology . John Wiley & Sons. pp. 221-244. ISBN  9781444348194 .

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