Response to selection for growth in successive mass selected generations of Iwagaki oyster Crassostrea nippona

Abstract

The Iwagaki oyster (Crassostrea nippona) is a potential aquaculture species with delicious taste and edibility in summer when the Pacific oyster (Crassostrea gigas) suffer from low meat quality. Although there is an increasing interest in hatchery mass production and field grow-out among farmers, large-scale expansion of C. nippona aquaculture has been compromised by unimproved growth performance. To improve the growth rate of C. nippona, we initiated the mass selective breeding program for fast growth in 2014 and estimated the genetic parameters of growth traits in the first three successive mass-selected generations. Each selected line exhibited better growth performance than the corresponding control group at all sampling dates. At grow-out stage, the average selection response (SR), realized heritability (hR2) and genetic gain (GG) for shell height was 0.45–0.56, 0.27–0.42 and 9.20–11.12% in the three mass selected lines, respectively. A significant increase in GG for shell height was observed in the third-generation selected line compared with that in the first-generation (P < 0.05). Meanwhile, the average SR (0.44–0.49) and GG (11.07–12.46%) for body weight of C. nippona were observed in the selective breeding program after three successive generations of mass selection. The encouraging results obtained in this study suggest that genetic variances still remain at a relatively high level in the breeding populations of C. nippona, and demonstrate the feasibility of improving the growth traits by selective breeding for C. nippona.