The history and current status of aquaculture genetics in Israel

Genetic improvement efforts in Israel have focused mainly on common carp (Cyprinus carpio) and tilapias and, only recently, on marine fish species. The breeding program for carp started in the late 1950s and concentrated on growth rate under different culture practices. Originally, the main approach was mass selection, but when this failed to produce results, efforts shifted to evaluating inbreeding and crossbreeding (resulting in wide commercial use of an Fl crossbred). Chromosome-set manipulations became the major tool in recent carp genetic research, aimed at producing triploid populations and gynogenetic ornamental carp lines. Color inheritance in ornamental carp is also being investigated. Hybridization among other cyprinids, including grass carp, bighead carp and crucian carp, was examined, but found to be of little aquaculture value. Genetic improvement of tilapias has focused on the all-male inter-specific hybrid Nile tilapia (Oreochromis niloticus) x Jordan tilapia (O. aureus). Evaluation of other hybrids did not identify any that is better under Israeli conditions. Sex inversion is also practiced, and current studies are being devoted to production of all-male populations by breeding sex-inverted individuals. Other studies involve color inheritance and performance of red tilapias and chromosome-set manipulations. Since realized heritability for growth rate in the gilthead sea bream (Sparus aurata) was estimated to be 0.45, a mass selection program was initiated. Preliminary results so far suggest a 20% response in growth rate per generation. Some efforts are being devoted to testing the benefits of crossbreeding and inter-specific hybridization with Diplodus sargus and red sea bream (Pagrus major). The latter hybrid was found to be sterile. Chromosome-set manipulations aimed at obtaining triploids and gynogenetic (clones) sea bream are also being examined. Genetic engineering efforts are currently directed mainly towards developing methods of producing transgenic carp and gilthead sea bream carrying exogenous GH genes.