Integrating molecular genetic technology with traditional approaches for genetic improvement in aquaculture species

Genetic improvement of aquaculture species offers a substantial opportunity for increased production efficiency, health, product quality and, ultimate ly, profitability in aquacultural enterprises. Technolo-gies exist that can be implemented immediately to improve multiple traits that have economic v alue, while simultaneously accounting for inbreeding effects. Genetic impro vement techniques for delivering genetic gain include formal definition of the breeding objective, estimation of genetic parameters that describe popu lations and their differences, evaluation of additive and non-additive gene tic merit of individuals or families and defining the structure of a breedi ng programme in terms of mating plans. Novel genetic technologies involving the use of DNA-based tools are also under development for a range of aquac ulture species. These gene marker technologies can be used for identificati on and monitoring of lines, families and individuals, monitoring and contro l of inbreeding, diagnosis of simply inherited traits and genetic improveme nt through selection for favourable genes and gene combinations. The identi fication of quantitative trait loci (QTL), and direct or linked markers for them, will facilitate marker-assisted selection in aquaculture species, en abling improvement in economically important traits, particularly those tha t are difficult to breed for, such as food conversion efficiency and diseas e resistance.