Opsaridium microlepis

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	ACTINOPTERYGII	CYPRINIFORMES	CYPRINIDAE

Scientific Name:

Opsaridium microlepis

Species Authority

(Günther, 1864)

Common Name/s:

English

–

Lake Salmon

Assessment Information [top]

Red List Category & Criteria:	Endangered A2bcd ver 3.1
Year Assessed:	2006
Assessor/s	Kazembe, J., Magombo, Z., Khawa, D. & Kaunda, E.
Evaluator/s:	Snoeks, J. (Freshwater Fish Red List Authority) & Darwall, W. (Freshwater Biodiversity Assessment Programme)
Justification: Endemic to Lake Malawi and its catchment. Population reduction is estimated at not less than 50% (from direct observations) in the last 10 years. The causes of population decline (overfishing, habitat degradation, and pollution) are ongoing.

Geographic Range [top]

Range Description:	Endemic to Lake Malawi and its affluent streams.
Countries:	Native: Malawi; Mozambique; Tanzania, United Republic of

Population [top]

Population:	Declining due to overfishing and habitat degradation.
Population Trend:	Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	A lacustrine species, living in the pelagic zone of the lake. Juveniles remain close inshore and near the river mouths. The adults are piscivourous, feeding on small pelagic fishes. Young fish feed on plankton, insects and other small organic matter. It migrates up rivers from the lake to spawn during the rainy season. Spawning mainly takes place at night and requires well-oxygenated flowing waters and silt free gravel. Spawning takes place in very shallow water and occurs over an extended period during and after the rains.
Systems:	Freshwater

Habitat and Ecology:

A lacustrine species, living in the pelagic zone of the lake. Juveniles remain close inshore and near the river mouths. The adults are piscivourous, feeding on small pelagic fishes. Young fish feed on plankton, insects and other small organic matter. It migrates up rivers from the lake to spawn during the rainy season. Spawning mainly takes place at night and requires well-oxygenated flowing waters and silt free gravel. Spawning takes place in very shallow water and occurs over an extended period during and after the rains.

Systems:

Freshwater

Threats [top]

Major Threat(s):	Over-fishing: extremely high mortalities of adults during spawning runs due to total blocking of rivers with gill nets and weirs as well as drifting gillnets. This prevents upstream migration in low rainfall years. Fish poisoning is widely practised although illegal. Deterioration of spawning grounds due to siltation from soil erosion (bad land practise as well as deforestation along rivers). Water abstraction for irrigation purposes during dry season hampers downstream movement of young fish.

Major Threat(s):

Over-fishing: extremely high mortalities of adults during spawning runs due to total blocking of rivers with gill nets and weirs as well as drifting gillnets. This prevents upstream migration in low rainfall years. Fish poisoning is widely practised although illegal. Deterioration of spawning grounds due to siltation from soil erosion (bad land practise as well as deforestation along rivers). Water abstraction for irrigation purposes during dry season hampers downstream movement of young fish.

Conservation Actions [top]

Conservation Actions:	One major river where this species breeds is the Bua river, which runs through the Nkhota Kota game reserve (Central Malawi). This is the only river where the spawning grounds are protected (as the surrounding woodlands are protected from deforestation). The headwaters of the North Rukuru river are also protected within the Nyika National Park — there is however increasing land clearance between the park and the spawning grounds. The Linthipe river, a major spawning river, is unprotected, receiving untreated effluent from Lilongwe. The status of 'mpasa' rivers in Tanzania and Mozambique is Unknown.

Conservation Actions:

One major river where this species breeds is the Bua river, which runs through the Nkhota Kota game reserve (Central Malawi). This is the only river where the spawning grounds are protected (as the surrounding woodlands are protected from deforestation). The headwaters of the North Rukuru river are also protected within the Nyika National Park — there is however increasing land clearance between the park and the spawning grounds. The Linthipe river, a major spawning river, is unprotected, receiving untreated effluent from Lilongwe. The status of 'mpasa' rivers in Tanzania and Mozambique is Unknown.

Citation:	Kazembe, J., Magombo, Z., Khawa, D. & Kaunda, E. 2006. Opsaridium microlepis. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 22 November 2008.
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