Nile perch
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| Lates niloticus (Linnaeus, 1758) |
The Nile perch (Lates niloticus) is a species of freshwater fish in family Centropomidae of order Perciformes. It is widespread throughout much of the Afrotropic ecozone, being native to the Lake Chad, Congo, Nile, Senegal, Volta, Lake Turkana and other river basins. It also occurs in the brackish waters of Lake Maryut in Egypt. Originally described as Labrus niloticus, among the marine wrasses, the species has also been referred to as Centropomus niloticus. Common names include the African snook and a large number of local names in various African languages.
Lates niloticus is silver in colour with a blue tinge. It has a distinctive dark black eye, with a bright yellow outer ring. One of the largest freshwater fish, it reaches a maximum length of nearly two metres (more than six feet), weighing up to 200 kg (440 lb).
Adult Nile perch occupy all habitats of a lake with sufficient oxygen concentrations, while juveniles are restricted to shallow or nearshore environments. A fierce predator that dominates its surroundings, the Nile perch feeds on fish (including its own species), crustaceans, and insects; the juveniles also feed on zooplankton.
Nile perch have been introduced to many other lakes in Africa, including Lake Victoria (see below). The IUCN's Invasive Species Specialist Group considers Lates niloticus one of the world's 100 worst invasive species.
The species is of great commercial importance as a food fish. The Nile perch is also popular with sport anglers and is raised in aquaculture.
[edit] Lake Victoria introduction
The Nile perch was introduced to Lake Victoria, in East Africa, in the 1950s, and since then it has been fished commercially. It is attributed with causing the complete or near-extinction of several hundred native species, but as Nile Perch stocks decrease due to overharvesting, at least some of them are making a comeback. Initially, the Nile perch's diet consisted of native cichlids, but with decreasing availability of this prey, it now consumes mainly small shrimps and minnows.
The fish's introduction to Lake Victoria, while ecologically negative, has stimulated the establishment of large fishing companies there. In 2003 Nile perch earned 169 million Euros in sales to the EU. The long-term outlook is less clear, as overfishing is now reducing Lates niloticus populations.
On the other hand, alteration of the native ecosystem has also had disruptive socioeconomic effects on local communities in the countries bordering the lake. Large-scale fishing operations, while earning millions of dollars from their exported Lates niloticus catch, have displaced many local people from their traditional occupations in the fishing trade and brought them into the cash economy.
The introduction of this species to Lake Victoria is one of the most commonly cited examples of the negative effects invasive alien species can have on ecosystems.
The Academy Award-nominated documentary Darwin's Nightmare by Hubert Sauper (a French-Austrian-Belgian production, 2004) deals with the damage that has been caused by Nile Perch introduction, including the import of weapons and ammunition in cargo planes from Europe that then export Nile Perch, exacerbating the conflict and misery in the surrounding regions.
[edit] References
- http://www.fao.org/docrep/005/T0037E/T0037E00.htm
- http://news.bbc.co.uk/2/hi/africa/4348289.stm
- Socio-economic effects of the evolution of Nile perch fisheries in Lake Victoria: a rewiew. J. Eric Reynolds and D.F. Greboval, CIFA Technical paper 17, FAO 1988, ISBN 92-5-102742-0
- IUCN. "Alien Species Invade the Planet". Press release, 11 May 2001.
- "Lates niloticus". FishBase. Ed. Ranier Froese and Daniel Pauly. October 2004 version. N.p.: FishBase, 2004.
- Lates niloticus (TSN 167670). Integrated Taxonomic Information System. Accessed on 20 December 2004.
- Lipton, David. "Lates niloticus: Information". Animal Diversity Web. Ann Arbor: University of Michigan Museum of Zoology, 2003.
- Snoeks, Jos. "Ecology of Lates niloticus". Global Invasive Species Database. Updated 22 September 2004.
- M.L. Bianchini (1995). Species introductions in the aquatic environment: changes in biodiversity and economics of exploitation. Proc. World Fish. Congress (Athens, 1992), 3: 213-222.
