Ruffe

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Ruffe
Ruffe in Pärnu River (Estonia)
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Family:	Percidae
Genus:	Gymnocephalus
Species:	G. cernua
Binomial name
Gymnocephalus cernua (Linnaeus, 1758)
Synonyms
Perca cernuus Linnaeus, 1758 Acerina cernua (Linnaeus, 1758) Holocentrus post Lacépède, 1802 Cernua fluviatilis J. Fleming, 1828 Acerina vulgaris G. Cuvier, 1829 Acerina fischeri Eichwald, 1873 Acerina czekanowskii Dybowski, 1874 Acerina cernua danubica Vladykov, 1931 (ambiguous) Acerina cernua essipovi Burmakin, 1941

The ruffe (Gymnocephalus cernua), also known as the Eurasian ruffe or pope, is a freshwater

The species occurs in the basins of the Caspian, Black, Aral, Baltic and North Sea, and is also found in Great Britain, parts of Scandinavia^[5] and some regions of the Arctic Ocean basin eastward to the drainage of the Kolyma. It has been introduced to parts of Western Europe (France, northern Italy) and Greece, as well as to the North American Great Lakes.^[1]

Diet

In Eurasia, the ruffe diet mainly consists of zoobenthos:

The ruffe has the capacity to reproduce at an extremely high rate. A ruffe usually matures in two to three years, but a ruffe that lives in warmer waters has the ability to reproduce in the first year of life. A single female has the potential to lay from 130,000 to 200,000 eggs annually. Ruffe will leave the deep dark water where they prefer and journey to warmer shallow water for spawning. The primary spawning season for the ruffe occurs from the middle of April through approximately June.^[9]

Life cycle

Life for the Eurasian ruffe, starts as an egg, like other fish. Egg sizes typically range from 0.34 to 1.3 mm (0.013 to 0.051 in) in diameter, depending on the size of the female.^[9] If the same female has a second batch in the same season, the eggs will be smaller than the first batch. The size of the second batch of eggs is about 0.36 to 0.47 mm (0.014 to 0.019 in), while the first batch of eggs goes from 0.90 to 1.213 mm (0.0354 to 0.0478 in) in size. If the female lays twice in one season, there is usually one in late winter/early spring and one in late summer. Hatching occurs in 5–12 days in temperatures of 10–15 °C (50–59 °F). The next stage in life is the embryonic/juvenile stage.

Other methods that have been considered are poison and chemical control. If a large school of ruffe is found, they can be poisoned. If some survive, however, they will rapidly reproduce. Chemicals can be targeted to act on specific species of fish. The chemical lampricide TFM kills ruffe, but leaves other fish unharmed.

As long as a couple of the fish survive, they can move and repopulate. The problem will increase if the ruffe invade southern river systems. The use of

Scientists have concluded three things:

• The pheromone repels the ruffe (it was unclear if it would in the beginning).
• The pheromone is species specific, so it would only repel the ruffe, none of the other fish.
• The pheromone is resilient to freezing, so could be used even during Minnesota's long winter season; the ruffe could still be controlled. By using this method, scientists could block ruffe from natural mating spots and produce a population decline; their goal is to kill the species in the Great Lakes.

Other invasive situations

Ruffe were first discovered in Loch Lomond, Scotland, in 1982, probably introduced as live bait by pike anglers. It is now abundant throughout the Loch. There are concerns about the effect of the huge ruffe population on the endemic whitefish population known as powan (Coregonus lavaretus) as ruffe prey on their eggs. Ruffe became the principal food item for the three main fish predators found in the area: the great cormorant, grey heron and northern pike.^[12]

References

Sources

• Gangl, James Allen. 1998. "Effects of Eurasian Ruffe (Gymnocephalus cernuus) and Yellow Perch (Perca flavescens)." M.S. Thesis. University of Minnesota, Duluth. Pg. 1–5
• McLean, Mike. "Ruffe: A New Threat to Our Fisheries." Minnesota Sea Grant. 24 July 2007.1 Oct 2007 http://www.seagrant.umn.edu/ais/ruffe_threat
• Peter J. Maniak; Ryan D. Lossing & Peter W. Sorensen (2000). "Injured Eurasian ruffe, Gymnocephalus cernuus, release an alarm pheromone that could be used to control their dispersal".
  doi:10.1016/S0380-1330(00)70685-X
  .
• Crosier, Danielle M., Molloy, Daniel P., Marsden, J. Ellen. "Ruffe – Gymnocephalus cernuus." New York State Museum. University of Vermont. October 23, 2007.

External links

Wikimedia Commons has media related to Gymnocephalus cernuus.

• GLANSIS Species FactSheet, United States Geological Survey
• Species Profile – Eurasian Ruffe (Gymnocephalus cernuus), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Eurasian Ruffe.