Shifts in the food of Nile tilapia,<i>Oreochromis niloticus</i>(L.) in Lake Victoria, Kenya

Njiru, M.; Okeyo-Owuor, J. B.; Muchiri, Mucai; Cowx, I. G.

doi:10.1111/j.1365-2028.2004.00503.x

Cited by 133 publications

(124 citation statements)

References 16 publications

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“…The nature of the diet could be a possible explanation for such an inter-specific differences in concentrations. L. niloticus are exclusively piscivorous, consuming all available fish species including its own siblings whereas O. niloticus relies on zooplankton and macroinvertebrates (Ogari, 1984;Njiru et al, 2004). Earlier studies established that PCBs can have great variations among different fish, as well as within species depending on their feeding habits and trophic levels (Suedel et al, 1994;Vander Zanden and Rasmussen, 1996;Davis et al, 2002;van der Oost et al, 2003).…”

Section: Concentrations Of Pcbs In Fish From the Murchison Baymentioning

confidence: 99%

Polychlorinated biphenyls in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda

Ssebugere

Sillanpää

Wang

et al. 2014

Science of The Total Environment

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• High concentrations of PCBs were found at sites near wastewater discharges.• The PCB concentrations were low to moderate compared to other locations worldwide.• Based on the European Commission set TEQ, the fish were fit for human consumption. Polychlorinated biphenyls (PCBs) were determined in sediments and two fish species collected from the Murchison Bay in Lake Victoria, using high resolution gas chromatography coupled to a high resolution mass spectrometer. Total PCB concentrations (Σ 18 PCBs) varied widely with mean values ranging from 777 to 4325 pg g −1 dry weight (dw) for sediments and 80 to 779 pg g −1 wet weight (ww) for fish. The PCB levels in the sediments were significantly higher at the station closest to Nakivubo channel, presumably due to effluents discharged by the channel, which may contain domestically produced commercial PCB mixtures. For fish, the concentrations in Nile perch (Lates niloticus) were significantly greater than those in Nile tilapia (Oreochromis niloticus) at all study stations, possibly due to dietary differences among species. World Health Organization-toxic equivalents (WHO 2005 -TEQs) for the dioxin-like PCBs were 0.04-0.64 pg g −1 dw and 0.01-0.39 pg g −1 ww for sediments and fish, respectively. The non-ortho PCBs exhibited the highest contribution to the Σ 12 TEQs (N75%) compared to the mono-ortho PCBs in both fish species. The TEQs in the present study were lower than many reported worldwide in literature for fish and were within the permissible level recommended by the European Commission, implying that the fish did not pose health hazards related to PCBs to the consumers. a b s t r a c t a r t i c l e i n f o

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Section: Concentrations Of Pcbs In Fish From the Murchison Baymentioning

confidence: 99%

Polychlorinated biphenyls in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda

Ssebugere

Sillanpää

Wang

et al. 2014

Science of The Total Environment

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“…In studies where the inundation of the margins of African lakes by flood waters has occurred, the combination of decaying submerged terrestrial vegetation and the increased fluvial input of nutrients has resulted in increased production of detritus, phytoplankton, periphyton and zooplankton (Weyl 2007), with phytoplankton production also enhanced by the decreased turbidity (Guenther and Bozelli 2004). In response to the inundation and increased food resources, production of the tilapia species increases (McKaye et al 1995;Bwanika et al 2004;Njiru et al 2004;Peterson et al 2004Peterson et al , 2005Britton et al 2009). Increased growth rate and recruitment success following flood events have also been generally observed in cichlid populations (Dudley 1975(Dudley , 1979De Silva 1985;Weyl 2007) and appears evident in Lake Naivasha (Britton and Harper 2008).…”

Section: Discussionmentioning

confidence: 99%

Management Implications of the Response of Two Tilapiine Cichlids to Long-Term Changes in Lake Level, Allodiversity and Exploitation in an Equatorial Lake

Oyugi

Harper

Ntiba

et al. 2011

AMBIO

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The tilapiine cichlids Oreochromis leucostictus and Tilapia zillii were introduced into Lake Naivasha, Kenya, in 1956. Previous studies on data collected to 1987 revealed they were persistent following establishment, despite environmental variability and exploitation. Recent data, however, suggest this persistence is under threat as data indicate some significant declines in aspects of their abundance since 1999. The influence of changes in lake level, allodiversity and fishing effort on this decline was tested and showed that a decline in lake level was a significant causal factor. The recent change in allodiversity, with the establishment and dominance of Cyprinus carpio in the fishery, was not significant on the catch per unit effort of O. leucostictus but was on T. zillii. Since 1999, catches of tilapiines in the fishery have been independent of fishing effort, contrary to between 1975 and 1987, suggesting their management through application of fishery models may no longer be applicable. As it was anthropogenic-mediated lake level changes that were mainly responsible for their decline, then lake management should focus on sustainable water utilization that maximizes lake levels in accordance with the basin-wide water balance.

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“…The flesh lipid is controlled by the available nutrition [17] the feeding frequency, sex, and maturity of the fish [18][19][20][21][22][23]. The minerals composition of fish body is determined by the harvest waters [24][25][26]. The concentration of minerals in the harvest waters influences the content of those minerals in the habitat fish [27].…”

Section: Discussionmentioning

confidence: 99%

Comparative Growth Performance and Proximate Nutrient Composition of Three Local Strains of Nile Tilapia (Oreochromis Niloticus L.) Collected From Different Locations in Uganda

Kwikiriza¹,

Barekye²,

Ar³

et al. 2017

Fish Aquac J

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The availability of O. niloticus fingerlings remains a problem in South Western Highland Agro-Ecological Zones. Most fish farmers produce only small sized fish probably because of inbreeding in Uganda. Brood stocks of Nile tilapia, Oreochromis niloticus L. were collected from Lakes Victoria, Kyoga and Kayumbu, a minor lake in SWHAEZ. The brood-stock were conditioned and bred. Fingerlings of F1 generation of each strain were fed diet containing 35% Crude Protein for 90 days. The results showed that Victoria strain growth performance was better compared to other tilapia strains in growth performance. Survival rate was not significantly different among Nile tilapia strains. Crude protein contents in fish body was higher in Victoria (69.30%) followed by Kayumbu strains (68.125%) with Kyoga having the least crude protein content (64.5%). Fish body of Kayumbu strains contained higher values of crude fat (11.70%) followed by Victoria strain (9.90%) while Kyoga strain had the least crude lipid (8.50%). The Victoria strain (47.8 g feed/fish) had significantly higher feed intake and PER than all the other strains. Kyoga and Kayumbu strains were comparable in terms of feed intake. However, the Kayumbu strain had significantly the least PER (2.46). The lowest FCR value was obtained in Kayumbu strain (1.67), while the higher ones were obtained in Kyoga and Victoria strains 1.82 and 1.78, respectively). The poor performance of kayumbu strain was probably due to in breeding and other environmental factors like temperatures. Therefore, exploitation of the genetic variation within the different native wild strains through selective breeding can help to improve growth performance of the Kayumbu strain in South Western Highland Agro-Ecological Zones (SWHAEZ).

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Shifts in the food of Nile tilapia,Oreochromis niloticus(L.) in Lake Victoria, Kenya

Cited by 133 publications

References 16 publications

Polychlorinated biphenyls in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda

Polychlorinated biphenyls in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda

Management Implications of the Response of Two Tilapiine Cichlids to Long-Term Changes in Lake Level, Allodiversity and Exploitation in an Equatorial Lake

Comparative Growth Performance and Proximate Nutrient Composition of Three Local Strains of Nile Tilapia (Oreochromis Niloticus L.) Collected From Different Locations in Uganda

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