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Open AccessArticle

Aquaculture-Mediated Invasion of the Genetically Improved Farmed Tilapia (Gift) into the Lower Volta Basin of Ghana

1
Department of Fisheries and Watershed Management, Kwame Nkrumah University of Science and Technology, PMB, University Post Office, Kumasi, Ghana
2
Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA
*
Author to whom correspondence should be addressed.
Diversity 2019, 11(10), 188; https://doi.org/10.3390/d11100188
Received: 18 July 2019 / Revised: 25 September 2019 / Accepted: 30 September 2019 / Published: 2 October 2019
(This article belongs to the Special Issue Biological Invasions 2020 Horizon)
The need for improved aquaculture productivity has led to widespread pressure to introduce the Genetically Improved Farmed Tilapia (GIFT) strains of Nile tilapia (Oreochromis niloticus) into Africa. However, the physical and regulatory infrastructures for preventing the escape of farmed stocks into wild populations and ecosystems are generally lacking. This study characterized the genetic background of O. niloticus being farmed in Ghana and assessed the genetic effects of aquaculture on wild populations. We characterized O. niloticus collected in 2017 using mitochondrial and microsatellite DNA markers from 140 farmed individuals sampled from five major aquaculture facilities on the Volta Lake, and from 72 individuals sampled from the wild in the Lower Volta River downstream of the lake and the Black Volta tributary upstream of the lake. Our results revealed that two farms were culturing non-native O. niloticus stocks, which were distinct from the native Akosombo strain. The non-native tilapia stocks were identical to several GIFT strains, some of which showed introgression of mitochondrial DNA from non-native Oreochromis mossambicus. We also found that the non-native cultured tilapias have escaped into the wild and interbred with local populations, and also observed potentially admixed individuals on some farms. Our results highlight aquaculture as a vector in the spread of invasive non-native species and strains, and underscore the importance of genetic baseline studies to guide conservation planning for wild populations. View Full-Text
Keywords: mitochondrial DNA; microsatellites; phylogenetic analysis; Oreochromis niloticus; Oreochromis mossambicus; D-loop; COI; hybridization mitochondrial DNA; microsatellites; phylogenetic analysis; Oreochromis niloticus; Oreochromis mossambicus; D-loop; COI; hybridization
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Anane-Taabeah, G.; Frimpong, E.A.; Hallerman, E. Aquaculture-Mediated Invasion of the Genetically Improved Farmed Tilapia (Gift) into the Lower Volta Basin of Ghana. Diversity 2019, 11, 188.

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