Genetic Improvement of Red Sea Bream (Pagrus major) in Korea : Growth Performance, Eggs Production and Health Assessment

Abstract

Red sea bream, Pagrus major, is an 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 report the effects of selection by fish size on growth enhancement of Korean strain of red sea bream and the comparative growth performance and health conditions of selected Korean strain, cultured Japanese strain and their reciprocal intraspecific hybrids. Offspring from selected line (5th generation of selection) showed significantly better performance in body weight, body length, weight gain, specific growth and feed consumption (but not in feed conversion ratio) than offspring from non-selected line (2nd generation of wild) in sea cages rearing trials with communal stocking. At 36 months after hatching offspring from selected line grew 1.49 times faster in body weight than offspring from non-selected line. Growth of selected Korean line (KORDI-F4), cultured Japanese line (JPN) and their reciprocal intraspecific hybrids lines were studied. In sea cages, offspring from JPN♀ⅩKORDI-F4♂ showed significantly faster growth (P<0.05, ANOVA, n=240) than other offspring groups (KORDI-F4♀ⅩKORDI-F4♂, KORDI-F4♀ⅩJPN♂, JPN♀ⅩJPN♂). Offspring groups from mating with JPN females (JPN♀ⅩKORDI-F4♂, JPN♀ⅩJPN♂) had shorter spawning period and less amount of fertilized eggs by natural mating in naturalze on growth enhancement of Korean strain of red sea bream and the comparative growth performance and health conditions of selected Korean strain, cultured Japanese strain and their reciprocal intraspecific hybrids. Offspring from selected line (5th generation of selection) showed significantly better performance in body weight, body length, weight gain, specific growth and feed consumption (but not in feed conversion ratio) than offspring from non-selected line (2nd generation of wild) in sea cages rearing trials with communal stocking. At 36 months after hatching offspring from selected line grew 1.49 times faster in body weight than offspring from non-selected line. Growth of selected Korean line (KORDI-F4), cultured Japanese line (JPN) and their reciprocal intraspecific hybrids lines were studied. In sea cages, offspring from JPN♀ⅩKORDI-F4♂ showed significantly faster growth (P<0.05, ANOVA, n=240) than other offspring groups (KORDI-F4♀ⅩKORDI-F4♂, KORDI-F4♀ⅩJPN♂, JPN♀ⅩJPN♂). Offspring groups from mating with JPN females (JPN♀ⅩKORDI-F4♂, JPN♀ⅩJPN♂) had shorter spawning period and less amount of fertilized eggs by natural mating in natural