Oreochromis mortimeri

Scope: Global

Language: English

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Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
Animalia	Chordata	Actinopterygii	Perciformes	Cichlidae

Scientific Name:

Oreochromis mortimeri (Trewavas, 1966)

Common Name(s):

English

–

Kariba Tilapia, Mozzie

Assessment Information [top]

Red List Category & Criteria:	Critically Endangered A2ae ver 3.1
Year Published:	2007
Date Assessed:	2007-03-01
Assessor(s):	Marshall, B.E. & Tweddle, D.
Reviewer(s):	Snoeks, J. (Freshwater Fish Red List Authority) & Darwall, W. (Freshwater Biodiversity Assessment Unit)
Justification: This species is declining rapidly in Lake Kariba and the Zambezi River and being replaced by the exotic species Oreochromis niloticus. There are no known refuges for the species. The rate of decline is at least 80% in the last 10 years. The species therefore qualifies as Critically Endangered under Criterion A2ae.

Geographic Range [top]

Range Description:

The middle Zambezi River and its tributaries from the Cahora Bassa Gorge to the Victoria Falls, the only endemic species in the middle Zambezi.

Countries occurrence:

Native:

Mozambique; Zambia; Zimbabwe

Additional data:

Range Map:

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Population [top]

Population:

Rapidly declining because of the introduction of Oreochromis niloticus. Has disappeared completely from parts of Lake Kariba and is decreasing in the river below the Kariba Dam and is likely to disappear from Lake Cahora Bassa since O. niloticus has reached that lake.

Current Population Trend:

Decreasing

Additional data:

Habitat and Ecology [top]

Habitat and Ecology:	A wide range of fluvial environments and flourished in Lake Kariba and quiet waters of the large rivers until the introduction of O. niloticus. Feeds on algae, especially diatoms, and detritus, and plants, insects and zooplankton. Breeds practically all year (Skelton 2001).
Systems:	Freshwater

Threats [top]

Major Threat(s):	The major threat is the exotic species O. niloticus which is displacing it throughout its range, having been introduced by anglers and aquaculturists.

Major Threat(s):

The major threat is the exotic species O. niloticus which is displacing it throughout its range, having been introduced by anglers and aquaculturists.

Conservation Actions [top]

Conservation Actions:	Conservation measures are urgently needed and pure stocks should be sought and kept in semi-captivity in areas without O. niloticus.

Conservation Actions:

Conservation measures are urgently needed and pure stocks should be sought and kept in semi-captivity in areas without O. niloticus.

Citation:	Marshall, B.E. & Tweddle, D. 2007. Oreochromis mortimeri. The IUCN Red List of Threatened Species 2007: e.T63337A12659594. . Downloaded on 26 April 2018.
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