Selection and Intraspecific hybrids in red sea bream. Part. I. Effects on growth performance

Abstract

Red sea bream, Pagrus major, is a important aquaculture fish species both in Korea and Japan and many genetic studies of this species were carried out for aquaculture purpose. In this paper we reported the effects of selection by fish size on growth enhancement of Korean strain of red sea bream and the comparative growth performance of selected Korean strain and cultured Japanese strain and their reciprocal intraspecific hybrids. Selection effects on growth performance of Korean strainOffspring from selected line (5th generation of selection) showed significantly better performance in body weight, body length, weight gain, specific growth rate and feed consumption (but not in feed conversion ratio) than offspring from non-selected line (2nd generation of wild) at sea cages rearing trials with communal stocking. At 36 months of age offspring from selected line grew faster 1.49 times in body weight than offspring from non-selected line.Growth of selected Korean, cultured Japanese and their reciprocal intraspecific hybridsUntil one month after hatching, two offspring groups from mating with KORDI-F4 females (KORDI-F4♀XKORDI-F4♂ and KORDI♀XJPN♂) showed significantly larger in length than offspring groups from mating with JPN females (JPN♀XKORDI-F4♂ and JPN♀XJPN♂) presumably due to the small egg size of JPN females. At sea cages, subsequently, offspring groups from JPN♀XKORDI-F4♂ grew faster significantly (P<0.05, ANOVA, n=240) than other offspring groups. These results demonstrate that the selection effects on growth performance in Korean strain. And the intraspecific hybrids between cultured Japanese female and selected Korean male had shown the heterosis in growth and resistance to low water temperature.