A survey of fishes of Hombolo Lake, Dodoma, Tanzania, with evidence for local extinction of a native tilapia as a consequence of stocking

Turner, George F.; Ngatunga, Benjamin P.; Genner, Martin J.

doi:10.1101/452847

Cited by 7 publications

(4 citation statements)

References 10 publications

(16 reference statements)

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“…Interference competition is speculated to have driven the declines of native tilapia species in Lake Victoria (Goudswaard et al, 2002), but direct evidence supporting this is lacking. Furthermore, it has been proposed that O. niloticus was responsible for the local extinction of the native tilapia species Oreochromis urolepis (Norman, 1922) from Lake Hombolo, Tanzania (Turner et al, 2019). These studies that implicate O. niloticus as the causal agent in the eradication of a native fish populations highlight the potential vulnerability of functionally similar tilapia species to O. niloticus invasion, and consequently interactions between O. niloticus and closely related species warrant investigation.…”

Section: Introductionmentioning

confidence: 99%

Invasive Nile tilapia dominates a threatened indigenous tilapia in competition over shelter

2020

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Invasive species are one of the greatest threats to freshwater ecosystems globally. However, the causal mechanisms that drive negative impacts of many invasive species are poorly understood. In Tanzania, non-native Nile tilapia (Oreochromis niloticus) exists in sympatry with a diverse range of native species, many of which are congenerics with strong niche overlap. It has been suggested that O. niloticus can displace native species from preferred habitat through dominance during interference competition, yet interference competition between O. niloticus and a native tilapia species has never been directly tested under experimental conditions. In this study juvenile O. niloticus and Manyara tilapia (Oreochromis amphimelas), a functionally similar but endangered Tanzanian cichlid, were size matched in conspecific and heterospecific pairs. We presented pairs with limited shelter and recorded competitive interactions. We found that O. niloticus were more aggressive and faster to initiate agonistic interactions than O. amphimelas. Furthermore, O. niloticus showed a strong competitive dominance in their interactions with O. amphimelas. One-sided dominance hierarchies can drive fundamental changes in resource use by subordinate individuals, potentially resulting in habitat displacement over the long term. Based on this experimental evidence, we conclude that O. niloticus may threaten native tilapia species through dominance in interference competition.

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Section: Introductionmentioning

confidence: 99%

Invasive Nile tilapia dominates a threatened indigenous tilapia in competition over shelter

2020

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“…The Mtera and Hombolo dams are the most popular fishing spots [ 38 , 40 ]. However, fish stocks in these dams have decreased dramatically due to overfishing and poor management, resulting in low catches [ 38 , 41 ]. As a result, aquaculture development is required to support the growing population.…”

Section: Methodsmentioning

confidence: 99%

Pond water quality and its relation to fish yield and disease occurrence in small-scale aquaculture in arid areas

Mramba

Kahindi

2023

Heliyon

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“…The study was conducted in Dodoma region in central Tanzania. The region is de ned by latitudes 4 o to 8 o south and longitudes 35 o to 37 o east (Turner et al 2019). The region hosts one of the largest Universities in Tanzania, the University of Dodoma.…”

Section: Study Areamentioning

confidence: 99%

The status and challenges of aquaculture development in Dodoma, a semi-arid region in Tanzania

Mramba

Kahindi

2022

Aquacult Int

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Demand for sh is growing rapidly in Tanzania due to population growth and rising incomes. However, as fewer wild sh are being caught, there is a gap in sh supply. Aquaculture is a viable alternative source to meet the gap in sh demand. Tanzania has the perfect climate and land for sh farming. Aquaculture in fresh and salt water has grown quickly, yet the potential is not being fully realised. Thus, the study assessed the growth of aquaculture in Dodoma, a rapidly developing semi-arid region of Tanzania, in order to determine its potential, challeges, and solutions. Thirty-six sh farmers from Dodoma urban district were visited and interviewed. The interviews gathered information about management practices, sh yield, and challenges the farmers experienced. The ndings indicated that aquaculture in the region began around nine years ago when the region began to expand. The aquaculture includes small-scale pond farming of Nile tilapia (Oreochromis niloticus) and African cat sh (Clarias gariepinus). Fish yield was about 1925 kg ha -1 per culture cycle, and sh customers are de nitely available. The main challenges were limited supply and high prices of sh feed and seeds, and limited water supply. Use of commercial feeds, pond fertilisation, access to extension services and ownership of a borehole were related to high sh yield. Expansion of aquaculture in the region is possible with the improvement of extension services and training of farmers in proper breeding, feeding, and water management. To decrease water demands, integrated aquaculture, water recycling, and aquaponics should be encouraged.

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A survey of fishes of Hombolo Lake, Dodoma, Tanzania, with evidence for local extinction of a native tilapia as a consequence of stocking

Cited by 7 publications

References 10 publications

Invasive Nile tilapia dominates a threatened indigenous tilapia in competition over shelter

Invasive Nile tilapia dominates a threatened indigenous tilapia in competition over shelter

Pond water quality and its relation to fish yield and disease occurrence in small-scale aquaculture in arid areas

The status and challenges of aquaculture development in Dodoma, a semi-arid region in Tanzania

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