Selection and intraspecific hybrids for growth in the red seabream, Pagrus major

Abstract

-Selection effects on growth of Korean strain Offspring from selected line 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 at sea cages rearing trials. At 12 months after hatching, offspring from selected line grew faster 1.21 times in body length and 1.30 times in body weight than offspring from non selected line.- Growth of selected Korean, cultured Japanese and their reciprocal intraspecific hybrids Until one month after hatching, two offspring groups from mating with KORDI- F4 females (KORDI-F4♀×KORDI-F4♂ and KORDI♀× JPN♂) showed significantly larger in length than the remainder two offspring groups from mating with JPN females (JPN♀×KORDI-F4♂ and JPN♀× JPN♂) due to the small egg size of JPN strain&apos;s female. There&apos;s no significance differences in fish size between offspring groups from mating with same females. At sea cages, subsequently, offspring groups from KORDI-F4♀×KORDI-F4♂ and JPN♀× JPN♂ grew faster significantly (P<0.05, Student&apos;s t-test, n=240) than offspring groups from their reciprocal mating groups (KORDI-F4♀× JPN♂ and JPN♀× KORDI-F4♂). In feeding trials, KORDI F4♀×KORDI F4♂ group had the highest feed intake and feed conversion ratio among four offspring groups. These results demonstrates that the selected line (KORDI-F4♀×KORDI-F4♂) of Korean strain had growth improvement (grew 1.3 times faster than non selected line in same strain) through selection by fish size and reciprocal intraspecific hybrids between selected Korean strain and cultured Japanese strain had not shown superior growth performance until juvenile stage.