Research on cultivation techniques of spotted babylon (Babylonia areolata) for commercial purpose

Results showed that B. areolata laid moderately transparent, vasiform egg capsules, which were firmly attached individually to the sand substratum by a long narrow stalk. The average egg capsule was 21.4 mm in length and 9.5 mm in width. On average, each breeder spawned 46 egg capsules and 851 eggs per capsule ranging from 493 to 1133. The average egg diameter was 425 microns. Embryonic development occurred inside the egg capsules during the first 7 days after spawning. Newly hatched larvae were 720 microns in shell length. They hatched through the apical opening of the egg capsule 8 days after spawning. Larval metamorphosis was accomplished within 18 days after hatching. Newly settled juveniles were 1520 and 1160 microns in shell length and width, respectively. Monthly average growth of larvae was 84.5 microns per day in shell length and average survival rate was 1.8-3.2 percent respectively. There were significant differences in both shell and tissue growth rates among the four nursery culture systems in most of the months (P0.05). The highest growth rates generally occurred at the nursery culture system of sand substratum with flow-through seawater, followed by system of sand substratum with static water and no sand substratum with flow-through seawater, respectively. Regardless the lowest growth rate is the suspened culture. At the end of the experiment, survival typically exceeded 80 percent for all nursery culture systems. The present study showed that the culture system of sand substratum with flow-through seawater can obtained the marketable size of 4.0-4.5 cm in shell length within 8 months. There were no significant differences in monthly mean environmental variations among 4 nursery culture systems (P0.05). Multiple regression analyses of shell growth with temperature, salinity, pH and dissolved oxygen as independent variables showed no significant for all nursery cultures and it may be concluded that growth of juveniles spotted babylon were not affected by these environmental variations among 4 nursery culture systems.