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Labeo victorianus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Cypriniformes Cyprinidae

Scientific Name: Labeo victorianus
Species Authority: Boulenger, 1901
Common Name(s):
English Ningu

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A2acde ver 3.1
Year Published: 2016
Date Assessed: 2015-11-04
Assessor(s): FishBase team RMCA & Geelhand, D.
Reviewer(s): Kishe, M., Natugonza, V., Nyingi, D. & Snoeks, J.
Contributor(s): Musschoot, T., Boden, G. & Bayona, J.D.R.
Justification:
Labeo victorianus, locally known as Ningu, is as an endemic cyprinid of the Lake Victoria basin. The predictable migratory habits of this anadromous species, coupled with its delicacy among the local communities have led to severe population declines (not less than 80% in 10 years) and shrinkage of its extent of occurrence (EOO). Additionally, regression of swamps and wetlands due to agricultural activities, sedimentation due to erosion on watershed and eutrophication contribute to continuing declines in habitat quality of the spawning grounds. This species is therefore listed as Critically Endangered.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is endemic to the Lake Victoria drainage (Seegers et al. 2003). It occurs in shallow, inshore waters of Lake Victoria (Van Oijen 1995) and affluent rivers such as the Nzoia (Whitehead 1959, Corbet 1961, Cadwalladr 1965a), Yala (Whitehead 1959), Sio (Rutaisire and Booth 2005) and Akagera (Corbet 1961) Rivers. It is also found in Lake Katwe and Lake Kubigena in Tanzania (Katunzi and Kishe 2004). The extent of occurrence (EOO) has decreased from a 20 m depth range observed during the 1969–71 survey (Kudhongania and Cordone 1974) to a 10 m range during the 1997–99 surveys (Okaronon et al. 1999, Getabu and Nyaundi 1999, Mkumbo and Ezekiel 1999). It is also reported from the Victoria Nile and Lake Kyoga system in Uganda (Greenwood 1966), the Middle and Upper Akagera system in Rwanda (De Vos et al. 2001) and the Ruvubu River in Burundi (De Vos 1991).
Countries occurrence:
Native:
Burundi; Kenya; Rwanda; Tanzania, United Republic of; Uganda
Additional data:
Continuing decline in extent of occurrence (EOO):Unknown
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:During the 1950s the catches of this fish in the Lake Victoria basin decreased dramatically as a result of intensive and unregulated gill-net fishing across river mouths (Garrod 1961, Cadwalladr 1965a, Ogutu-Ohwayo 1990). Removing gravid, sexually mature fish at the beginning of their migration resulted in significant population declines. Additionally, large numbers of fry were taken in scoop-traps on their return to the lake (Ogutu-Ohwayo 1990). By the early 1960s L. victorianus had virtually disappeared from the catches of the Lake Victoria (Cadwalladr 1965a). It is common in commercial fish catches in the Upper and Middle Akagera lakes. It has a wide extent of occurrence but is very rarely encountered.
Current Population Trend:Decreasing
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Labeo victorianus is an potamodromous species. It spends most of its life span in lakes (Eccles 1992), and ascends both large rivers and streams in fairly compact shoals (Whitehead 1959) during the rainy season (Fryer and Whitehead 1959) to spawn. Spawning grounds are flooded grasslands beside both permanent and temporary streams (Eccles 1992). Submerged rocky cliffs and shelves near the river mouths are favoured by non-reproducing fish prior to migrating upstream to spawn (Rutaisire and Booth 2005). However, Oweke Ojwang et al. (2007) indicate that upstream migrations are virtually gone and reports that this once-migratory species is now possibly a sedentary riverine resident. Permanent river populations indeed exist (Whitehead 1959, Oweke Ojwang et al. 2007). In Lake Victoria this Labeo occurs in shallow, inshore waters and influent rivers (Witte and Winter 1995) and in Lake Kyoga it lives in open waters away from water-lily zones (Greenwood 1966). Labeo victorianus is a specialized feeder on epilithic and epiphytic algae (Corbet 1961), but mud, plant debris (Greenwood 1966) and rotifers growing on the bodies of other fishes are also taken (Fryer et al. 1955). The maximum size is 41.0 cm SL (Van Oijen 1995).
Systems:Freshwater
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):2-3.3
Movement patterns:Full Migrant

Use and Trade [top]

Use and Trade: In the 1950s Ningu was one of the most abundant fish landed in the Lake Victoria basin. A flourishing, seasonal fishery based on this species existed in the mouths of several affluent rivers. Fish with ripe eggs were regarded as a delicacy.

Threats [top]

Major Threat(s): Intensive and unregulated gill-netting of gravid fishes across rivers or river mouths during the seasonal spawning migration is a threat. Loss of spawning/nursery grounds due to siltation, pollution and water extraction also occurs as a result of agricultural extension in the Lake Victoria catchment. Regression of swamps and other wetlands around lakes and rivers due to farming extension (rice, sorghum, banana plantations) is a threat in the Bugesera depression. Sedimentation due to excessive soil erosion (mining activities, road and building construction, cultivation on steep slopes, etc.) and pollution occurs in  the Rweru-Mugesera lakes-wetlands complex with agrochemicals. Loss of riverine migratory routes and competitive displacement by introduced fish species are also threats.

Conservation Actions [top]

Conservation Actions: This species is found in the Akagera and Ruvubu National Parks. It was identified in the Lake Victoria Environmental Management Project (LVEMP) as one of the species for restoration. Several studies are being carried out to provide the scientific knowledge that will facilitate the domestication of Ningu as a way of restoring its declined population. Usually, bays and gulfs with affluent rivers are legislated as closed areas for fishing from 1st January to 30th June each year in order to protect spawners and juveniles. Policy based action is needed to decrease the degradation of the lake as well as to prevent overfishing around river mouths and in the upstream spawning areas, and protected areas should be established. More information is needed on the current population size and trend. 


Citation: FishBase team RMCA & Geelhand, D. 2016. Labeo victorianus. The IUCN Red List of Threatened Species 2016: e.T60318A47182908. . Downloaded on 09 December 2016.
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