Principal Investigator: Dr. James Barasa

This is a collaborative research project between the University of Eldoret, Kenya and the University of Potsdam, Germany.

Objective: The long-term aim is to develop an all-male tilapia strain for commercial aquaculture in Kenya. Economic production of farmed tilapias globally relies on use of all-male tilapia seed, since males grow faster than females, and mixed sex cultures lead to prolific breeding in culture facilities, yielding many small sized fish of low market value. 

The Problem: Current methods of producing mono sex male tilapia seed are inefficient, technically complex, and require large facilities and pure tilapia species and strains, which are difficult to achieve at farms and hatcheries. Furthermore, the most common method, the use of steroids is environmentally unfriendly and only achieves at most 70-94% sex reversal of the batch. This potentially leads to spawning in culture, despite the farmer having purchased and paid for all-male tilapia seed from hatcheries. Such seed is also unsuitable for stocking in cages in Lake Victoria, as fry from breeding activities in cages escape to the open waters of the lake, where they negatively interact with natural tilapias of the lake.  A more efficient and easier method of producing 100% all-male tilapia seed for use by farmers is therefore an urgent need.

The project: The approach involves studying molecular pathways of sex determination in tilapias, in combination with several strategies including sex reversal, hybridization, and genomic selection to develop a strain that yields 100% all-male fry. 

The first phase is underway, initiated last year with the visit to Germany by the Kenyan PI, James Barasa. During the visit, requisite genomic resources were developed, tested, and validated via laboratory analyses, at the University of Potsdam. The visit was supported by the German Research Fund (DFG) and the Third World Academy of Sciences (TWAS).

The second phase of the project was initiated this year, by the visit of the PI from Germany, Prof. Dr. Ralph Tiedemann, and co-PI Dr. Marisol Dominguez to the University of Eldoret, Kenya, in September. During the visit, the researchers undertook joint fieldwork, for fish sampling at different lakes and fish farms. They also carried out technical backstopping and discussions with members of the management committee for the Fish Genetics and Genomics Training and Research Laboratory. Their visit and fieldwork were supported by the University of Potsdam Research grant for collaborative activities in sub-Saharan Africa.

Next steps: The project will seek support from diverse funding streams to support research work, especially by postgraduate students, both at the Fish Genetics and Genomics Training and Research Laboratory and fish hatchery at the University of Eldoret, Kenya, as well as at the Institute of Evolutionary Biology and Biochemistry at University of Potsdam, Germany.