Browsing by Author "Fermin, A. C."
Reproductive performance of hatchery-bred donkey's ear abalone, Haliotis asinina, Linne, fed natural and artificial diets Hatchery-bred donkey's ear abalone, Haliotis asinina, Linne broodstock were given diets consisting of natural food, seaweed (SW), Gracilariopsis bailinae, D1; combination of SW and artificial diet (AD), D2; and AD alone, D3. Equal numbers of 1 : 1 female and male abalone were stocked in 24 units, 60 L tanks with eight replicate tanks per dietary treatment. Reproductive performance, e.g. number of spawnings, instantaneous fecundity and egg hatching rates, was monitored over 270 days. The mean number of spawnings was not significantly different among treatments. The mean instantaneous fecundity and percent hatching rates were significantly higher in abalone fed D2 or D3 compared to those given D1. Survival of abalone broodstock fed D1 was, however, significantly higher at 88% than those fed either D2 or D3 at 75%. Fatty acid analysis showed that the n-3/n-6 fatty acid ratios of abalone hepatopancreas reflected those of their diets. Mature abalone ovary had n-3/n-6 fatty acid ratio of 1.3. A higher amount of essential nutrients in the artificial diet such as protein, lipid and the highly unsaturated fatty acids, e.g. 20 : 4n-6, 20 : 5n-3, 22 : 6n-3 in abalone fed D2 or D3, may have influenced the increased reproductive performance.
Year-round sexual maturation of bighead carp Aristichthys nobilis (Richardson) reared in floating cages in Laguna de Bay (Philippines). AC Fermin -
Journal of Applied Ichthyology, 1990 - Blackwell PublishingSexual maturation in bighead carp Aristichthys nobilis reared without supplemental feeding in floating cages in Laguna de Bay was observed year-round. Percent maturation ranged from 3 to 94% in females and 0 to 82% in males from July 1985 to July 1986. High maturation rates in both sexes occurring in March 1986 were positively correlated with high inorganic turbidity in the lake. Low natural food productivity (phyto- and zooplankton) during high turbidity did not negatively affect fish growth. Fish may have depended partly on suspended particles as additional food sources when production of more suitable food (zooplankton) was low. Increased production of natural food as a result of water clearing by seawater intrusion during May to September did not enhance growth and maturation of the fish. There was a low negative correlation between chlorinity and percent maturation of both sexes.