Growth, survival and gonad development of two new types of reciprocal triploid hybrids between Crassostrea gigas and C. angulata

Abstract

The allotriploid technology has been widely applied to aquaculture worldwide. To overcome the deficiency of low growth, poor taste and high mortality of diploid hybrids between Crassostrea gigas and C. angulata in summer, two new types of triploid hybrids were produced by inhibiting the polar body II using cytochalasin B. The growth, survival and gonad traits of triploid hybrids (TGA – C. gigas ♀ × C. angulata ♂ and TAG – C. angulata ♀ × C. gigas ♂), diploid hybrids (GA – C. gigas ♀ × C. angulata ♂ and AG – C. angulata ♀ × C. gigas ♂) and purebred crosses (GG – C. gigas ♀ × C. gigas ♂ and AA – C. angulata ♀ × C. angulata ♂) were evaluated. A high triploidy induction rate (> 95%) was found by ploidy analysis. The fertilization and hatch rates of triploid hybrids were significantly (P < 0.05) lower than that of diploid crosses. During the larval stage, the triploid advantage (TA) was positive in growth, despite was negative in survival. The triploid hybrids exhibited superior performance during the grow-out stage. Across three culture environments (Rongcheng, Rushan and Huangdao), triploid hybrids performed better than diploid hybrids in growth with an increasing value of TA over time. The incremental survival rates of triploid hybrids, especially that of TGA, were significantly (P < 0.05) higher than that of diploid hybrids at Rushan and Huangdao in summer. The TA in cumulative survival rate ranged from 13.80% to 36.04% among environments. A positive yield advantage for diploid and triploid hybrids was observed at Rongcheng (mid-parent heterosis H: 114.11%; TA: 35.76%), Rushan (H: 148.22%; TA: 48.78%) and Huangdao (H: 138.96%; TA: 60.22%). Additionally, most of the triploid hybrids exhibited high sterility during reproduction phase. These findings demonstrated that triploid hybrids between C. gigas × C. angulata had obvious advantage in growth, survival and yield, which have important application value for commercial oyster cultivation in northern China.