Browsing by Subject "Tropical abalone"
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Aquaculture, 1999 - ElsevierThe effects of different stocking densities on the growth, feed conversion ratio and survival of two size groups of the tropical abalone Haliotis asinina were determined. Three culture trials were conducted in net cages installed in a sheltered cove, Guimaras Province, Philippines. Trials 1 and 2 were conducted using 15–20 mm abalone juveniles for 150 days, while trial 3 was conducted using 35–40 mm abalone for 180 days. The animals were fed sufficient amounts of the red alga, Gracilariopsis bailinae (=G. heteroclada), throughout the experiment. There was an inverse relationship between growth (length and weight) and stocking density. Feed conversion ratio was not influenced by density, but was observed to be higher for larger animals. Survival was not significantly affected by density. Net cages are appropriate for culture of H. asinina. This study showed that H. asinina can reach commercial size of about 60 mm in one year. It also showed that growth of H. asinina can be sustained on a single-species diet. An economic analysis will be important in choosing the best stocking density for commercial production.
Optimal sperm concentration and time for fertilization of the tropical abalone, Haliotis asinina Linné 1758 -
Aquaculture, 1998 - ElsevierCurrent interest in the tropical abalone, Haliotis asinina has generated research into seed production and culture techniques. However, there has been no report regarding the optimal sperm concentration for fertilization and development, and gamete viability for this species. Spawned eggs of H. asinina were artificially fertilized using eleven final sperm concentrations ranging from 1×102 to 1×107 sperm ml−1. In another experiment, eggs were fertilized using sperm spawned at the same time at a final sperm concentration of 1×105 sperm ml−1 at 1, 2, 3, 4, and 5 h after spawning. Sperm concentrations of 5×103 to 1×105 sperm ml−1 gave both maximal fertilization rate and normal trochophore development. The sperm to oocyte ratio of this range is 1×103 to 2×104. Gametes were still viable 2 h after spawning; both fertilization and normal development rates decreased when fertilized later. It is recommended to use 1×105 sperm ml−1 for artificial fertilization of H. asinina eggs within 2 h after spawning.
Aquaculture, 1998 - ElsevierThe sex ratio, initial size at sexual maturity, spawning period, time interval between successive spawnings and fecundity of the Donkey's ear abalone, Haliotis asinina were studied. The sex ratio of wild abalone (>60 mm shell length) collected from Panagatan Cays, Antique, Philippines was approximately 1:1. Sexual maturity was first attained at a size of 35.0 mm and 35.9 mm for hatchery-reared male and female abalone, respectively, and 40.6 mm for wild-caught male and female specimens. Based on calculated gonad bulk indices and histological observations, wild-caught abalone appeared capable of spawning during most months of the study period except June for males and May–June for females, during which most specimens collected were at a resting stage. This abalone species is a serial spawner with an asynchronous spawning behavior. Hatchery-reared abalone have short time intervals between successive spawnings of 13–15 days. Ripe females measuring 58.1–69 mm in shell length may release about 150,000 to 600,000 eggs per spawning.