Zambia is the leading aquaculture producer in Southern Africa with the current fish production from the sector at 89,342 MT 1. There are several indigenous and exotic tilapia species cultured in Zambia’s aquaculture industry. Oreochromis andersonii, commonly known as the three-spot tilapia, is among the commonly farmed indigenous species. The production of exotic species of tilapia is limited to designated production regions and prohibited in areas where indigenous species like O. andersonii naturally occur, limiting productivity and profitability of aquaculture farmers in these areas who depend on the species genetically unimproved seed. Growth rate, feed conversion efficiency and survival are the main determinants of productivity in fish farming and improving these traits is crucial. The objective of this paper is to present the genetic improvements achieved through pedigree-based selection, in the first two generations (G1 & G2) of the Genetic Improvement Program (GIP) funded by the Government of Zambia and the African Development Bank.
The pedigree-based program targeting growth as the key trait, commenced in 2019 with disease free founder populations from the Kafue, Luangwa and Zambezi River systems. The first generation was produced in 2022 and we found a significant heritability for growth rate. We achieved 12.6% genetic gain for growth in the first generation and 11.5% in the second generation. Our results are similar to the 12% (range of 3.6% to 20.5%) average genetic gain per generation obtained for growth for tilapia based on 17 estimates of 4.6 average number of generations of selection2. Currently, the third generation (G3) of O. andersonii is under grow-out stage and the GIP has disseminated its first batch of the generation two (G2) improved seed to the government hatchery which will in turn multiply and disseminate to farmers across major aquaculture zones in Zambia.
The significant heritability and genetic gains for growth achieved over the last two generations of O. andersonii indicates growth can be improved by selective breeding in the species. Improved growth in the species means a relatively shorter production cycle, reduced costs and increased profitability for O. andersonii farmers. Integration of new traits including survival and feed conversion efficiency will further benefit the program.
References
1Department of Fisheries (DoF), Zambia. Fisheries and Aquaculture Statistics: Annual Report; Ministry of Fisheries and Livestock:Chilanga, Zambia, 2024.
2Gjedrem T, Rye M (2018) Selection response in fish and shellfish: a review. Reviews in Aquaculture 10, 168–179.