Suitable initial body sizes juvenile spotted babylon (Babylonia areolata L.) for growing out to marketable sizes in a large-scale flow-through system.

摘要

Suitable initial body sizes of juvenile spotted babylon (Babylonia areolata) for growing out to marketable sizes were determined under a large-scale flow-through system. Juveniles were graded by size into six groups of initial body sizes: traditional size (T; 0.29 pl 0.007 g/snail); medium size 1 (M1; 0.16 pl 0.009 g/snail); medium size 2 (M2; 0.13 pl 0.002 g/snail); medium size 3 (M3; 0.12 pl 0.006 g/snail); small size 1 (S1; 0.09 pl 0.007 g/snail); and small size 2 (S2; 0.07 pl 0.005 g/snail). A comparison was performed at the end of the experiment between the growth of small spotted babylon and the other size groups to confirm that the growth performance of small-size groups was better than the others. There were no significant differences in average weight gain between the six size groups (P < 0.05). The average weight gain ranged from 4.13-4.27 g/snail, 4.00-4.25 g/snail, and 3.97 g/snail in the small sizes, medium sizes, and large size, respectively. However, the average specific growth rate in body weight of both small sizes (S1: 2.73% day-1;; S2: 2.59% day-1) was also significantly higher than those of the medium sizes (2.19%-2.39% day-1) and the large size (1.79% day-1). ANOVA of SGR by size groups showed significant differences between the six size groups (P < 0.05). Intergroup comparisons by Tukey's test revealed that SGR differed significantly except S1 vs. S2. The final survival rate was higher than 96% for all growth trials and ranged from 96.40%-97.50%; no significant difference in survival between the six size groups was found. This study shows that juveniles of small size grew faster than the other size groups.