SELECTIVE BREEDING FOR GROWTH IN RED-SEA BREAM

We attempted to improve the breed of red sea bream Pagrus major by mea ns of selective breeding in order to establish red sea bream seedling for aquaculture capable of growing more quickly than natural red sea b ream. In about 1964, natural young fish were reared into broodstock an d, among young fish obtained from these broodstock, those growing quic kly were selected and reared into broodstock. This selective breeding has been repeatedly carried out for more than 25 years. The following results were obtained. (1) As the selective breeding was repeated, the body weight of broodstock aged 4 years showed an increase. (2) The se lected red sea bream seedling grew at an obviously elevated rate as th e selective breeding was repeated. Namely, the time (days) required fo r attaining a commercially available fish size (about 1 kg) was shorte ned. (3) The average realized heritability, which was determined by th e average body weight of 4-year-old broodstock and body weight of 4-ye ar-old fish in the growth curve of each generation, was 0.33 +/- 0.28.