Browsing by Subject "Abalones"
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Photoperiod effects on feeding, food conversion, growth, and survival of abalone (Haliotis asinina Linne) during nursery rearing - In J Hylleberg & A Nateewathana (Eds.), Proceedings of the 11th International Congress & Workshop of the Tropical Marine Mollusc Programme (TMMP), 28 September - 8 October 2000, Kodaikanal, Rameswaram and Tuticorin, Tamilnadu, India, 2001 - Phuket Marine Biological CenterJuveniles of Haliotis asinina, 10 mm shell length were subjected to four photoperiodic regimes namely, 6L:18D, OL:24D, diffused 12:12D, and ambient light (12L:12D) serving as control. Juveniles were fed fresh seaweed, Gracilariopsis bailinae, in excess amounts throughout the experiment. At the end of a 105-day experiment, juveniles held under ambient photoperiod were significantly bigger and had higher average daily growth rate than the rest of the treatments. Feed conversion efficiency was higher at ambient light than at other photoperiodic regimes. Daily feeding rates at 65-day culture period were similar for all treatments; however towards the end of culture period, feeding rate of abalone at ambient light was lowest compared to the rest of the treatments. Percent survival was significantly higher in animals at ambient light and at 6L: 18D with 99% and 97% respectively, than at other photoperiodic regimes.
Shell marking by artificial feeding of the tropical abalone Haliotis asinina Linne juveniles for sea ranching and stock enhancement -
Aquaculture Research, 2003 - Blackwell PublishingA method of marking abalone (Haliotis asinina Linne) for sea ranching and stock enhancement purposes was developed. Three-month-old abalone juveniles (11.8-mm shell length, 0.28 g) were fed artificial diets for 1, 2, or 3 weeks. The width of the bluish-green shell band produced by abalone juveniles was 1.7, 2.6, and 4.2 mm after 1, 2, or 3 weeks of feeding respectively. The growth and survival of juveniles fed artificial diets did not differ from that of juveniles fed the seaweed Gracilariopsis bailinae (control). Feeding the diet-fed juveniles with the seaweed thereafter produced the natural brownish shell, thus forming a sandwiched bluish-green band. An experimental release in outdoor tanks with natural growth of seaweeds and diatoms, and in a marine reserve showed that the shell band remained clear and distinct, indicating the usefulness of this shell marking method in sea ranching and stock enhancement of abalone.
Spontaneous spawning, fecundity and spawning periodicity in the donkey's ear abalone Haliotis asinina Linnaeus 1758 - In A Hylleberg (Ed.), Proceedings of the 10th International Congress and Workshop of the Tropical Marine Mollusc Programme (TMMP), 20-30 October 1999, Hanoi and Haiphong, Vietnamen, 2000 - Phuket Marine Biological Center; Phuket Marine Biological Center Special Publication 21(1)Spontaneous group spawning was monitored in wild-caught (WC) and hatchery-bred (HB) abalone broodstock (Haliotis asinina) held in duplicate tanks at 1:3 (male: female) ratio from June 1997 to January 1999. Abalone breeders (mean SL, wild = 69-79 mm, HB = 68-71 mm) were kept in perforated plastic baskets and fed red alga, Gracilariopsis bailinae, to excess given at weekly intervals. Abalone spawned spontaneously year-round. Water temperature during the study ranged from 26-29 degree C. A total of 139 and 128 spawning episodes were recorded for WC and HB group respectively. Spawning in WC group (mean: 7 ± 0.8) were more frequent in September (1998) and from February to April. Spawning frequency in the HB group (mean: 6.4 ± 1) was generally high during September (1998) until April. Likewise, egg production was highest during these months. Pooled mean survival from trochophore to veligers stage ranged from 7 to 30% (n=36). Potential fecundity was determined in sacrificed group of HB females (n=21) varied from 6,741-11,902 oocytes g -1 BW. Mean oocyte diameter ranged from 136 to 150 mu m. Bigger females had higher potential fecundity (range: 6.2 to 11 x 105 oocytes individual -1 than smaller females (range: 2.8 to 3.3 x 105 oocytes individual -1). The time interval between successive spawning among animals that spawned more than twice during a 5-month period ranged from 13 to 34 days for the small-size group and from 18 to 37 days for large-size group. In separately stocked HB females (without male), instantaneous fecundity was shown to range between 1,500 and 12,300 eggs g -1 BW (n=16). In contrast to potential fecundity, smaller and younger individuals gave higher 68-71 instantaneous fecundity (range: >3,000 >12,000 oocytes g -1 BW) than the bigger and older individuals (1,500-6,500 oocytes g -1 BW).