Induced spawning, seed production, and juvenile growth of the donkey's ear abalone Haliotis asinina Linne, 1758
1998
Tanate Poomtong | Songchai Sahawatcharin | Kongsak Sanguanngam (Department of Fisheries, Bangkok (Thailand). Coastal Aquaculture Development Center)
Total of 180 hatchery-raised abalone Haliotis asinina Linne were conditioned to photo-periods of 12 h light and 12 h darkness. Reversal of day and night periods made abalones change spawning behaviour and release gametes during day time. Spawning started after 7-10 days and continued from February to August 1996 without further treatment. The abalones produced a total of 40 million fertilised eggs. Survival of individual stages varied considerably. Calculated from the previous stage, survival was 60 percent to veliger stage, 48 percent to creeping larval stage, 10-20 percent to shell length of 2 mm (1 month), 40 percent to shell length of 5 mm (2 months), and 60 percent to shell length of 10 mm (3 months). The monthly hatchery production was 39,497 juveniles with a shell length of 10 mm. Juveniles were reared in plastic cages suspended in the sea or kept in the raceway of the hatchery. The latter showed higher growth rate but lower survival rate. However, no statistical difference was found between the treatments.
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