Perception Channels: tactile ; chemical
IUCN Red List of Threatened Species: least concern
The growth of the Nile perch is very fast during the first year. The rate then decreases during the second, third, fourth and fifth years.
The introduction of the Nile Perch to Lake Victoria has caused serious ecological problems. The richness and diversity of endemic cichlid species is rapidly declining. Over 300 native species have already been driven to extinction due to the feeding patterns of the Nile perch (Schofield, 1999). Although for the time being the strong increase of L. niloticus seems to be a favorable development for the fishing industry, the final consequences may be very serious for future fish production in the lake (Goudswaard and Witte, 1984). Since the increase of Nile perch, the accelerated decline in diversity has altered the food web structure and caused ecological changes due largely to human actions, which have profound socioeconomic effects (Kitchell and Schindler, 1997). The continuing degradation of Lake Victoria's ecological functions has serious long-term consequences for the ecosystem services it provides and may threaten social welfare in the different countries bordering its shores (Verschuren and Johnson, 2002). Also since the increase of Nile perch, smaller scale fishing companies have been hurt significantly.
The Nile perch has yielded an increase in total fishery, and fishery-related employment has increased dramatically. Since the increase of Nile perch, larger factory fishing companies have thrived greatly.
Positive Impacts: food
The Nile perch acts as a major predator in its native and introduced habitats.
Nile perch have been observed with several different kinds of parasites, Lernea (region after the operculum), arguilids (in the gills), and various nematodes (throughout the body).
The diet of Nile perch consists of fishes, insects, crustacea and mollusks. The type of prey ingested by the predator depends on the predator size, prey availability and abundance within a given habitat (Ogari, 1984). Juvenile Nile perch feed on copepods, prawns in the genus Caridina, fish fry, small gastropods, and bivalves. As the fish matures and moves to greater depths haplochromine cichlids constitute over 95% of their food consumption. Occasional items found in the Nile perch's diet include smaller fish in the genera Barbus, Clarias, Haplochromis, Lates, Oreichromis, and Xenoclarias. Besides crustacean zooplankton, invertebrate prey includes snails, clams, and insects (odonate larvae, aquatic Hemiptera, mayflies in the genus Povilla, and larvae of phantom midges (Chaoborus). Fish in the genus Rastrineobola are very common in the diet in terms of occurrence, and are second to haplochromines (Acere, 1985). As Nile perch grow larger, they take larger prey. Nile perch less than 80 cm tend to feed on smaller fishes than those greater than 80 cm. This demonstrates that the predator is capable of shifting to other sizes of prey when more suitable sizes become scarce (Ogutu-Ohwayo, 1984).
Animal Foods: fish; insects; mollusks; aquatic crustaceans; zooplankton
Primary Diet: carnivore (Piscivore )
Lates niloticus (Nile perch) is widespread throughout the Ethiopian Region of Africa, occurring commonly in all major river basins including Nile, Chad, Niger, Senegal and Volta. The nilotic population penetrates northwards well into the geographical limits of the Mediterranean Region and is present in the waters of Lake Mariout situated in the Nile Delta. Southwards the distribution includes parts of the Congo Basin. The most common place to find the Nile perch is in Lake Victoria where the species was introduced in 1962.
Biogeographic Regions: nearctic (Introduced ); ethiopian (Introduced , Native )
Nile perch are found in many different types of fresh water. They prefer warm, tropical waters (27°N – 7°S) where they grow to large sizes and occur in high densities. Adult Nile perch occupy all habitats in lakes and rivers (10-60 m in depth) where there is enough oxygen with the exception of rocks, swamps, and the pelagic zone. Small juveniles are restricted to shallow near-shore environments (Luna, 2002; Queensland Government, 2002).
Range depth: 0 to 60 m.
Habitat Regions: tropical ; freshwater
Aquatic Biomes: lakes and ponds; rivers and streams
Wetlands: marsh
Nile perch live up to the age of 16 years. There is a higher mortality rate for males than females.
Typical lifespan
Status: wild: 16 (high) years.
Average lifespan
Status: captivity: 7.8 years.
Nile perch are silver in color with a blue tinge. They have a distinctive dark black eye with a bright yellow outer ring. Nile perch are usually seen around 2-4 kg, but have been caught and seen at sizes up to 200 kg (the largest at 232 kg). They average around 85-100 cm but can grow to 193 cm. The females are generally larger than males. The preopercle and pre-orbital bones are armed with spines, with a large spine on the free edge of the operculum.
Range mass: 232 (high) kg.
Average mass: 2-4 kg.
Range length: 193 (high) cm.
Average length: 85-100 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Nile perch are sexually dimorphic. The male has only anal and urogential openings just anterior to the anal fin, whereas the female has a genital orifice separate from the urinary opening. They become sexually mature at the age of 3 years. Males dominate the sex ratio up to 80 cm TL, while the females are dominate at 80 cm TL and above (Asila and Ogari, 1988). Ovulation takes place in the spring with the rising water temperature. Spawning is usually done in sheltered areas, but can also occur in open waters.
Breeding season: Breeding peaks from March to June.
Range number of offspring: 3,000,000 to 15,000,000.
Average number of offspring: 9,000,000.
Average gestation period: 20 hours.
Average age at sexual or reproductive maturity (female): 3 years.
Average age at sexual or reproductive maturity (male): 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Average age at sexual or reproductive maturity (female)
Sex: female: 912 days.
Parental Investment: no parental involvement
There are 141 species of fish recorded in the Senegal River, most of which are native; however, there are no endemic species of fish in the Senegal Basin. Among the larger native benthopelagic taxa are: the 170 centimetre (cm) North African Catfish (Clarias gariepinus), the 149 cm Electric Catfish (Malapterurus electricus), and the 92 cm African Carp (Labeo coubie).
Some of the larger native demersal fishes of the Senegal Basin are: the 204 cm Aba (Gymnarchus niloticus). the 200 cm Nile Perch (Lates niloticus), the 183 cm Sampa (Heterobranchus longifilis), and the 150 cm Cornish Jack (Mormyrops anguilloides).
Pelagic native fishes in the Senegal River include the 65 cm True Big-scale Tetra (Brycinus macrolepidotus) and the 16 cm Ansorge Fangtooth Pellonuline (Odaxothrissa ansorgii)
The Nile perch (Lates niloticus), also known as the African snook, Goliath perch, African barramundi , Goliath barramundi, Giant lates or the Victoria perch, is a species of freshwater fish in family Latidae of order Perciformes. It is widespread throughout much of the Afrotropical realm, being native to the Congo, Nile, Senegal, Niger and Lake Chad, Volta, Lake Turkana, and other river basins. It also occurs in the brackish waters of Lake Maryut in Egypt. The Nile perch is a fish of substantial economic and food-security importance in East Africa.[2] Originally described as Labrus niloticus, among the marine wrasses, the species has also been referred to as Centropomus niloticus. Common names include African snook, Victoria perch (a misleading trade name, as the species is not native to Lake Victoria, though they have been introduced there), and many local names in various African languages, such as the Luo name mbuta or mputa. In Tanzania, it is called sangara, sankara, or chenku. In Francophone African countries, it is known as capitaine. Its name in the Hausa language is giwan ruwa, meaning "water elephant".
L. niloticus is silver in color with a blue tinge. It has distinctive dark-black eyes, with a bright-yellow outer ring. One of the largest freshwater fishes, it reaches a maximum length of nearly 2 m (6 ft 7 in), weighing up to 200 kg (440 lb).[3] Mature fish typically range from 1.21–1.37 m (4 ft 0 in – 4 ft 6 in), although many fish are caught before they can grow this large.[4]
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, molluscs,[5] and insects; the juveniles also feed on zooplankton. Nile perch use schooling as a mechanism to protect themselves from other predators.[6][7]
Nile perch have been introduced to many other lakes in Africa, including Lake Victoria and the artificial Lake Nasser. The World Conservation Union's Invasive Species Specialist Group considers L. niloticus one of the world's 100 worst invasive species.[8]
The state of Queensland in Australia levies heavy fines on anyone found in possession of a living Nile perch, since it competes directly with the native barramundi, which is similar and grows to 1.5 m (4 ft 11 in) long, while the Nile perch grows to 2.0 m (6 ft 7 in) long.[9]
The species is of great commercial importance as a food fish. The Nile perch is also popular with sport anglers, as it attacks artificial fishing lures, and it is also raised in aquaculture.[10]
The introduction of this species to Lake Victoria is one of the most cited examples of the negative effects alien species can have on ecosystems.[12]
The Nile perch was introduced to Lake Victoria in East Africa in the 1950s,[13][14] and has since been fished commercially. In 2003, Nile perch sales to the EU reached 169 million euros. Sport-fishing in the region of Uganda and Tanzania provided additional income from tourism.
Its introduction was ecologically disruptive and is attributed with causing the extinction or near-extinction of several hundred native species, with some populations fluctuating with commercial fishing and the actual Nile perch stocks. The Nile perch initially fed on native cichlids, but with decreasing availability of this prey, it now consumes mainly small shrimp and minnows.
The alteration of the native ecosystem had disruptive socioeconomic effects on local communities bordering the lake. Many local people have been displaced from their traditional occupations in the fishing trade and brought them into the cash economy, or before the establishment of export-oriented fisheries, turned them into economic refugees. At least initially, nets strong enough to hold adult Nile perch could not be manufactured locally and had to be imported for a high price.[15]
The introduction of Nile perch has also had additional ecological effects on shore. Native cichlids were traditionally sun-dried, but because Nile perch have a high fat content (higher than cichlids), they need to be smoked to avoid spoiling. This has led to an increased demand for firewood in a region already hard-hit by deforestation, soil erosion, and desertification.
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, which are then used to export Nile perch, further exacerbating conflict and misery in the surrounding regions.[16]
Regardless of whether it is considered positive or negative,[17] the trophic web of Lake Victoria appears to have been drastically impoverished by the introduction of this novel near-top-level predator. While the ecosystem seems to be moving towards a new equilibrium, neither its former state nor the state of fisheries on Lake Victoria can ever easily be brought back.[18][19][20]
On Lake Victoria, the only (small) trawlers present belong to research institutes. Small-scale fishing boats are propelled mostly by sails, and paddles are used on the smallest boats. However, the number of boats propelled by outboard engines is on the rise, denoting a greater capital intensity of the local Nile perch fishery.[21] One to three fishermen use a boat. The fish are caught mainly with gill nets and hand lines and sometimes (short) long lines. Those caught by gill nets are usually dead when the nets are lifted. The fish are kept in the boat without protection or ice and taken to landing sites, mostly beaches, where they are weighed and purchased by company buyers using insulated boats or vans with ice, or the fish are bought by local women.[22]
The fishery also generates indirect employment for additional fish processors, transporters, factory employees, and others. All along the lakeshore, 'boom towns' have developed in response to the demands of fishing crews with money to spend from a day's fishing.[Note 1] These towns resemble shanties, and have little in the way of services. Of the 1,433 landing sites identified in the 2004 frame survey, just 20% had communal lavatory facilities, 4% were served by electricity, and 6% were served by a potable water supply.[24][25][26]
Despite being a successful invasive species, the fish faces threats. Being a species of megafauna, the most obvious threats to the species are overfishing and the use of illegal fishing gear, as well as invasive water hyacinths. Prey depletion is also a factor, as it decreases the size of the fish and makes it vulnerable to larger predators, such as crocodiles.
In 2021, The Uganda Fish Processors and Exporters Association called on the parliament to ban the local consumption of the species so as to protect its export.[27]
The Nile perch (Lates niloticus), also known as the African snook, Goliath perch, African barramundi , Goliath barramundi, Giant lates or the Victoria perch, is a species of freshwater fish in family Latidae of order Perciformes. It is widespread throughout much of the Afrotropical realm, being native to the Congo, Nile, Senegal, Niger and Lake Chad, Volta, Lake Turkana, and other river basins. It also occurs in the brackish waters of Lake Maryut in Egypt. The Nile perch is a fish of substantial economic and food-security importance in East Africa. Originally described as Labrus niloticus, among the marine wrasses, the species has also been referred to as Centropomus niloticus. Common names include African snook, Victoria perch (a misleading trade name, as the species is not native to Lake Victoria, though they have been introduced there), and many local names in various African languages, such as the Luo name mbuta or mputa. In Tanzania, it is called sangara, sankara, or chenku. In Francophone African countries, it is known as capitaine. Its name in the Hausa language is giwan ruwa, meaning "water elephant".