Sex ratio and growth performance of gynogenetic diploid barfin flounder Verasper moseri

Barfin flounder

The effects of rearing temperature and genetic factor on the sex ratio of normal and gynogenetic diploids were examined in barfin flounder Verasper moseri. In addition, growth performance at the age of 6 to 34 months after hatching was also examined. In 16℃ (16.1±0.14) group, the percentage of females in gynogenetic diploids (G1) and normal diploids (2N) was significantly lower than in 14℃ (13.6±0.33) and 12℃ (12.0±0.30) group. However, no clear difference was observed in the female rate between 14℃ and 12℃ group. These results indicated that rearing temperature affects the sex ratio of both G1 and 2N, and high temperature (16℃) condition induced male-biased sex ratios. Among gynogenetic strains, female rates widely varied from 7.0% to 95.1% in the 14℃ and 12℃ condition. However, several cases exhibited high female rates (89.5 to 95.1%), suggesting that this species essentially has the male heterogametic (XX female-XY male) sex determination system. At 34 months, body weight of G1 (1569.0±328.4 g) was significantly heavier than 2N (866.6±283.8 g). Survival rates of 2N and G1 from 6 to 34 months were 98.0% and 96.0%, respectively. These results indicate that the group with a high percentage of females showed better growth.