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UPV Theses and Dissertations

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1983 - 198911990 - 19981

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    Growth of the telescope snail, Telescopium telescopium (Linne) in brackishwater ponds
    Apistar, Jobert H. (Division of Biological Sciences, College of Arts and Sciences, University of the Philippines, 1998-04)
    Samples of T. telescopium were collected every month, from April to October 1997 for 6 months, in brackishwater ponds. Allometric relationships were defined by comparing shell length with shell width, as well as various body weight proportions including total weight with shell, total volume with shell, visceral weight and visceral volume. A total of 5 cohorts with growth rates ranging from 0.45 - 0.67 mm-day- were observed using the Bhattacharya analysis. A high mean growth rate of 0.56 mm-day- (sd = 0.07, n= 5) was estimated by joining the modes of the cohorts between successive sampling months. Low inverse correlations were observed between mean shell length and various environmental parameters (i.e. salinity, air temperature, water temperature and organic matter content) possibly explained by the species' environmental adaptations. On the other hand significant correlation was observed between mean shell length and density, indicating the possible role of overcrowding in these habitats.
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    A comparative study of the effects of supplementary feeding and artificial substrate on the production of milkfish fingerlings in brackishwater ponds
    Adeyemi, Frederick F. (University of the Philippines Visayas, 1983-03)
    The growth and survival of milkfish fry in response to supplementary feeding and artificial substrate were evaluated at stocking densities of 75 and 100 fry/m2 for a period of 56 days from August 21 to October 15, 1982. The study was conducted in eighteen 40m2 experimental nursery ponds of the University of the Philippines Brackishwater Aquaculture Centre, Leganes, Iloilo. A 3 x 2 factorial experiment in completely randomized design was used and six treatment combinations between level of inputs (no inputs, supplementary feeding or artificial substrate) and stocking density (75 or 100 fry/m2) were investigated with three replicates per treatment. The best fish growth was obtained in Treatment VI (100 fry/m2 with substrate) with mean final weight and length of 1.59 gm. and 5.36 cm. respectively while Treatment IV (100 fry/m2 without feeding or substrate) gave the poorest fish growth with mean final weight and length of 0.83 gm. and 4.60 cm. respectively. Differences in mean weight and length among treatments were, however, not statistically significant. Mean percentage survival was significantly higher at a stocking density of 75 fry/m2 (82.8%) than at 100 fry/m2 (64.1%) but supplementary feeding or artificial substrate ix did not show any statistically significant effect on survival. At either 75 or 100 fry/m2 stocking density, supplementary feeding gave a numerically higher percentage survival than artificial substrate. Economic analysis revealed that a stocking density of 75 fry/m2 without supplementary feeding or artificial substrate was the most profitable treatment with a return on investment of 39.2%. At a stocking density of 100 fry/ m2, supplementary feeding with rice bran was more profitable than the use of artificial substrate with returns on investment of 22.6% and 9.1% respectively.