Suitable Initial Body Sizes of Juvenile Spotted Babylon (Babylonia areolata L.) for Growing Out to Marketable Sizes in a Large-Scale Flow-Through System

Abstract

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 ± 0.007 g/snail); medium size 1 (M1; 0.16 ± 0.009 g/snail); medium size 2 (M2; 0.13 ± 0.002 g/snail); medium size 3 (M3; 0.12 ± 0.006 g/snail); small size 1 (S1; 0.09 ± 0.007 g/snail); and small size 2 (S2; 0.07 ± 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.

KEYWORDS:

• Babylonia areolata
• growing out
• flow-through system
• initial body sizes
• growth
• survival

We thank the National Research Council of Thailand (NRCT) for providing the funding for this research during the period 2003–2008. I wish to express my special thanks to Professor Yutaka Natsukari, Faculty of Fisheries, Nagasaki University, Japan, for his interest in this research and revision of the manuscript.