Practical genetics in Israeli mariculture: History and present status

The aim of this review is to show the progress and achievements made to date in the selective breeding of cultured marine fish in Israel. The National Center for Mariculture (NCM) in Eilat was the first scientific organization to determine that a long-term selective breeding program is the key strategy for genetic improvement of commercially important marine fish. The main objective of the program is the development of genetically improved strains. The immediate practical goal is to improve the profitability of national mariculture through growth improvement in the gilthead sea bream (Sparus aurata). In this species, due to reproductive constraints that limit the prospects for family selection, mass selection was found to be the most practical tool for growth improvement. Currently, the selective breeding program for sea bream consists of several selected lines. Four cycles of mass selection for growth have been completed in commercial pro- duction environments. Mass selection and crossbreeding are integrated in the program. In the Eilat hatchery sea bream strain, a recessive deleterious Mendelian mutation (named “ebony”) was isolated by classical crossing experiments. A method was developed to use ebony for genetic protection of selected sea bream strains from unlicensed reproduction and propagation. Interspecific hybridization, chromosome set manipulation, and cytogenetic and sex control tech- niques were also applied; some were shown to be promising tools for short-term genetic improvement. In general, the NCM selective breeding program for sea bream showed that genetic gain for growth and faster economic return can be achieved within a “reasonable” time span of 10-12 years. The program is supervised by the Genetics and Physiology Department of the NCM. Presently, most Israeli commercial mariculture is using genetically improved strains of sea bream and newly domesticated strains of sea bass (Dicentrarchus labrax).