Progeny-testing selection of tilapia broodstocks producing all-male hybrid progenies — Preliminary results

Abstract

Prolific and uncontrolled reproduction of tilapias in production ponds is one of the most serious limitations in tilapia culture. Monosex culture by manual sexing is a practical method to overcome this problem, but requires skilled manpower and is time consuming and wasteful. The early promise of a genetic solution by the use of interspecific all-male hybrids has not been realized on a commercial scale due to broodstock management problems. None of the existing genetic models for sex determination is capable of serving as a breeding tool. Furthermore, intrapopulation variation for sex determination was demonstrated in Israeli populations of Sarotherodon aureus and S. niloticus. In order to obtain reliable broodstocks for commercial production of all-male S. niloticus × S. aureus hybrids, single pairs consisting of a female from one species and a male from the other are progeny-tested. The selection criterion used is the sex ratio in the hybrid progenies of these interspecific crosses. In crosses involving a S. niloticus female and a S. aureus male, all-male progenies are required for selecting the parents. In the reciprocal crosses the required sex ratio is 1 female: 3 males. Preliminary results confirm that some, but not all, S. niloticus × S. aureus pairs yield all-male progenies.