Oreochromis jipe

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	ACTINOPTERYGII	PERCIFORMES	CICHLIDAE

Scientific Name:

Oreochromis jipe

Species Authority

(Lowe-McConnell, 1955)

Common Name/s:

English

–

Jipe Tilapia

Assessment Information [top]

Red List Category & Criteria:	Critically Endangered B1ab(i,iii,v) ver 3.1
Year Assessed:	2006
Assessor/s	Bayona, J.D.R. & Hanssens, M.
Evaluator/s:	Snoeks, J. (Freshwater Fish Red List Authority) & Darwall, W. (Freshwater Biodiversity Assessment Programme)
Justification: This species is restricted to an EOO of less than 100 km², is only found in two small lakes and the connecting river, and is suffering from a continued decline in population (mature individuals) due competition for habitat, siltation, overfishing and weed infestation.

Geographic Range [top]

Range Description:	Endemic to Lake Jipe, which is approximately 16 km², in the Pangani drainage (Mugisha et al. 1993). It has since managed to colonise Nyumba ya Mungu (extent of occurrence (EOO) = 56 km²) via the river Ruvu. The total estimated EOO is therefore 72 km² (i.e., less than 100 km²).
Countries:	Native: Kenya; Tanzania, United Republic of

Population [top]

Population:	In Lake Jipe the fishery for this species declined towards 1958, following the introduction of O. esculentus. Combined with the problems of infestation by Typha dominingensis and Cyperus papyrus, the fishery was closed in 1960. Samples collected by De Vos in the Kenyan waters of the lake (about 5% by area) in 1998 indicated the existence of the species but at very low abundance. Observations by Bwathondi (2000) indicate that the species declined to less than 9% of the community. In the Nyumba ya Mungu reservoir the population was reported to decline to less than 10% of the community in 2000 as compared to 1974 when the species made up approximately 46.2% of the catch (Denny and Bailey 1976). The mean catch within the reservoir 1973 and 1978 was 3,412 tons for a fishing effort of 755 canoes (Nhwani 1988). By 2000, the annual reported catch had declined to 521 tons with 534 canoes (Horril 2000). The population decline is estimated at 95.5% in 28 yrs.
Population Trend:	Decreasing

Population:

In Lake Jipe the fishery for this species declined towards 1958, following the introduction of O. esculentus. Combined with the problems of infestation by Typha dominingensis and Cyperus papyrus, the fishery was closed in 1960. Samples collected by De Vos in the Kenyan waters of the lake (about 5% by area) in 1998 indicated the existence of the species but at very low abundance. Observations by Bwathondi (2000) indicate that the species declined to less than 9% of the community. In the Nyumba ya Mungu reservoir the population was reported to decline to less than 10% of the community in 2000 as compared to 1974 when the species made up approximately 46.2% of the catch (Denny and Bailey 1976). The mean catch within the reservoir 1973 and 1978 was 3,412 tons for a fishing effort of 755 canoes (Nhwani 1988). By 2000, the annual reported catch had declined to 521 tons with 534 canoes (Horril 2000). The population decline is estimated at 95.5% in 28 yrs.

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	This species prefers riverine habitats or inshore areas of the reservoir for grazing and refuge (Bailey et al.1999). It feeds mainly on microscopic algae, mostly periphyton, although the presence of inorganic particles and organic debris in the stomach indicates that food is also taken from the bottom (Trewavas 1983). There is no peak breeding season (Trewavas 1983). Max. size: 345 mm SL (Trewavas 1983).
Systems:	Freshwater

Habitat and Ecology:

This species prefers riverine habitats or inshore areas of the reservoir for grazing and refuge (Bailey et al.1999). It feeds mainly on microscopic algae, mostly periphyton, although the presence of inorganic particles and organic debris in the stomach indicates that food is also taken from the bottom (Trewavas 1983). There is no peak breeding season (Trewavas 1983). Max. size: 345 mm SL (Trewavas 1983).

Systems:

Freshwater

Threats [top]

Major Threat(s):	Over-fishing of juveniles and destruction of habitats by use of small meshed nets e.g., beach-seines of 49 mm in mesh size. Infestation by Typha dominingensis, Cyperus papyrus and Phragmites mauritianus. High levels of siltation. Competition for space/habitat between this species and O. esculentus. Increased salinity due to reduction in lake level.

Major Threat(s):

Over-fishing of juveniles and destruction of habitats by use of small meshed nets e.g., beach-seines of 49 mm in mesh size. Infestation by Typha dominingensis, Cyperus papyrus and Phragmites mauritianus. High levels of siltation. Competition for space/habitat between this species and O. esculentus. Increased salinity due to reduction in lake level.

Conservation Actions [top]

Conservation Actions:	The lake fishery was closed in 1960 to allow recovery and only very few artisanal fishermen exploit Lake Jipe. On the Kenyan side of the lake there is no exploitation because the lake falls within Tsavo National Park.

Conservation Actions:

The lake fishery was closed in 1960 to allow recovery and only very few artisanal fishermen exploit Lake Jipe. On the Kenyan side of the lake there is no exploitation because the lake falls within Tsavo National Park.

Citation:	Bayona, J.D.R. & Hanssens, M. 2006. Oreochromis jipe. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 22 November 2008.
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