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Marcusenius victoriae 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Osteoglossiformes Mormyridae

Scientific Name: Marcusenius victoriae
Species Authority: (Worthington, 1929)
Common Name(s):
English Victoria Stonebasher
Taxonomic Notes: Also reported as Gnathonemus victoriae (old binomen) (Seegers et al. 2003). Marcusenius rheni (Fowler, 1936) is considered to most likely be a junior synonym of Marcusenius victoriae (Worthington, 1929) according to Seegers et al. (2003) (see also Greenwood 1966), but this still needs to be formally confirmed.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2016
Date Assessed: 2015-12-22
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., Twongo, T.K. & Kazembe, J.
Facilitator/Compiler(s): Darwall, W.R.T.
Justification:
Marcusenius victoriae occurs from the Lake Kyoga system to the Middle Akagera system in Rwanda. Although there are no recent fishery statistics for the main lake to confirm this, it is thought that the population has now stabilised (pers. comm. Mary Kishe, Vianny Natugonza & Dorothy Wanja), this is especially true for the minor lakes where fishery records are more recent. The Victoria Stonebasher is therefore listed as Least Concern. More study is needed to verify the status of subpopulations in the main Lake Victoria.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is found in the Lake Victoria basin in Uganda (Greenwood 1966), Tanzania (Eccles 1992) and Kenya (Seegers et al. 2003). In the lake itself it is restricted to bays associated with rivers (e.g., Rubafu/Kagera; Mori bay/river; and Mara bay/river). Marcusenius victoriae is also reported from the Victoria Nile, Lake Kwania (Worthington 1929b), Lake Kyoga (Worthington 1929a, 1929b), Lake Nabugabo (Chapman and Hulen 2001) and Lake Katwe. It is present in reasonable numbers in the majority of lakes in the Kyoga system (Ogutu-Ohwayo et al. 2013) and is also widespread in the minor lakes in Tanzania within the Lake Victoria basin (Katunzi et al. 2010). This mormyrid also occurs in the Middle Akagera system in Rwanda (De Vos et al. 2001).
Countries occurrence:
Native:
Kenya; Rwanda; Tanzania, United Republic of; Uganda
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Information on relative abundance is scant. It is common in fisheries catches in Akagera associated lakes. The population size in lakes in the Lake Victoria basin declined as a result of competition from introduced fish species (Ogutu-Ohwayo 1990, Ogutu-Ohwayo 1995, T.K. Twongo pers. comm. 2003). For example, M. victoriae disappeared from the open waters of Lake Nabugabo after introduction of the predatory Nile Perch. It persisted in small, hypoxic wetland lagoons separated from the main lake by a few kilometres of fringing swamp (Chapman and Hulen 2001). Over-fishing of the Nile Perch has allowed modest resurgence of this mormyrid in Lake Nabugabo (Chapman et al. 2003). However, in the main Lake Victoria there is no indication for a recovery and it is thought to probably have stabilised (Mary Kishe, pers comm.). It is present in reasonable numbers in the majority of lakes in the Kyoga system (Ogutu-Ohwayo et al. 2013). It is also widespread in the minor lakes in Tanzania within the Lake Victoria basin (Katunzi et al. 2010).
Current Population Trend:Unknown
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:Marcusenius victoriae has a broad habitat distribution that includes extremely hypoxic swamps and the open waters of lakes and rivers (Chapman and Hulen 2001). In Lake Kyoga M. victoriae occurs in or near water lily swamps (Worthington 1929a). In Lake Victoria it occurs in shallow, inshore waters over sandy and rocky habitats, and seasonally over muddy bottoms adjacent to extensive papyrus swamps (Okedi 1971). It is predominantly insectivorous, feeding mainly on chironomid larvae (Corbet 1961), Polymitrarcidae and Odonata (Okedi 1971). It also eats small organisms like Ostracoda, Hydracarina (Corbet 1961, Okedi 1971), Conchostraca (Corbet 1961) and Diaptomus (Okedi 1971). Crustaceans, gastropods, fish eggs and detritus are also part of the diet (Okedi 1971). Marcusenius victoriae breeds twice a year during the rainy seasons and migrates up rivers (e.g. Sondu, Sio rivers) to spawn (Okedi 1969). The maximum size is 26.0 cm TL (Seegers et al. 2003).
Systems:Freshwater
Generation Length (years):1-3.3
Movement patterns:Full Migrant

Use and Trade [top]

Use and Trade: Mormyrid species are not often eaten in Uganda due to local beliefs that they lead to mental health problems. They are however eaten in Kenya and Tanzania.

Threats [top]

Major Threat(s): Water turbidity and siltation as a consequence of erosion and farming expansion, regression of wetlands and swamps due to extension of agriculture and human settlements, irrigation, eutrophication, loss of riverine migratory routes, predation by Nile Perch, fisheries pressure and illegal fishing methods are all threats to this species.

Conservation Actions [top]

Conservation Actions: No conservation actions are known for this species. Monitoring of the population trend is needed to verify whether M. victoriae is re-emerging in Lake Victoria and associated lakes as a result of intense fishing of Nile Perch (Balirwa et al. 2003).

Citation: FishBase team RMCA & Geelhand, D. 2016. Marcusenius victoriae. The IUCN Red List of Threatened Species 2016: e.T60365A47185200. . Downloaded on 23 May 2017.
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