Limited hybridization between introduced and critically endangered indigenous tilapia fishes in Northern Tanzania

Stephanie J. Bradbeer*, Jack Harrington, Henry Watson, Abrahim Warraich, Asilatu Shechonge, Alan Smith, Rashid Tamatamah, Benjamin P. Ngatunga, George F. Turner, Martin J. Genner

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

13 Citations (Scopus)
280 Downloads (Pure)


Hybridization between introduced and indigenous species can lead to loss of unique genetic resources and precipitate extinction. In Tanzania, the Nile tilapia (Oreochromis niloticus) and blue-spotted tilapia (Oreochromis leucostictus) have been widely introduced to non-native habitats for aquaculture and development of capture fisheries. Here, we aimed to quantify interspecific hybridization between these introduced species and the indigenous species Oreochromis esculentus, Oreochromis jipe and Oreochromis korogwe. In the Pangani basin, several hybrids were observed (O. niloticus × O. jipe, O. leucostictus × O. jipe, O. niloticus × O. korogwe), although hybrids were relatively uncommon within samples relative to purebreds. Hybrids between the native O. jipe × O. korogwe were also observed. In the Lake Victoria basin, no evidence of hybrids was found. Analysis of body shape using geometric morphometrics suggested that although purebreds could be discriminated from one another, hybrids could not be readily identified on body and head shape alone. These results provide the first evidence of hybridization between the introduced species and the Critically Endangered O. jipe in Tanzania. Given uncertainty regarding benefits of introduced species over large-bodied indigenous species in aquaculture and capture fisheries, we suggest that future introductions of hybridization-prone species should be carefully evaluated.

Original languageEnglish
Pages (from-to)257-268
Number of pages12
Issue number1
Early online date18 Apr 2018
Publication statusPublished - Apr 2019


  • Cichlid fish
  • Conservation
  • Freshwater fish
  • Introgression
  • Invasion biology

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