UPV Theses and Dissertations
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Item A comparative study of the effects of supplementary feeding and artificial substrate on the production of milkfish fingerlings in brackishwater pondsAdeyemi, 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.Item Effects of different levels of Pinus tebulaeformis pollen on growth and stress resistance of milkfish fry (Chanos chanos)Baldove, Analyn B. (University of the Philippines Visayas, 2010-06)The present study investigated the effects of different inclusion levels of pine pollen from Pinus tabulaeformis Carr. on the growth performance and stress resistance of milkfish fry (Chanos chanos). Milkfish fry with average body weight of 0.02 g were stocked in 15 tanks (40 fish per tank). A control diet (without pine pollen) and four experimental diets were prepared containing different levels of pine pollen at 0 g kg-1, 1.3 g kg-1, 2.6 g kg-1, 3.8 g kg-1, and 5.1 g kg-1 was fed to the experimental fish for 60 days. At the termination of the experiment, milkfish were subjected to acute ammonia and high salinity shock test. The result of feeding trial revealed that milkfish fed diets containing different levels of pine pollen stowed significantly higher growth (p < 0.05) in terms of weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio than the control diet. Survival of the milkfish during the trial were not significantly different among treatments (p > 0.05). Survival rates of milkfish groups exposed to high salinity stock test for 72 h were not significantly different from each other (p > 0.05). In contrast, results of the ammonia stress test revealed that the survival rates of milkfish fed with the diets containing (2.6 to 5.1 g kg-1) were significantly higher (p <0 .05) than those fed with diets containing 1.3 g kg-1 and the control diet Optimum dietary PP level was estimated using the quadratic model by using SGR and FCR values and found to be is 2.9 g kg-1 and 3.0 g kg-1, respectively. conclusion, pine pollen can be used as a supplement in milkfish diet to enhance growth and stress resistance against environmental stressors like ammonia.Item Assessment of induced stress as schemes for selectively removing fish with opercular deformities in hatchery produced milkfish (Chanos chanos) seedsCordero, Christian P. (College of Fisheries and Ocean Sciences, University of the Philippines Visayas, 2015-06)The effects of different types of induced stress were tested as schemes for the elimination of fish with opercular deformities in hatchery produced milkfish seeds. Salinity and pH were used as the main stressors for milkfish larvae of different ages. Induced salinity stress was initially tested on larvae at 15 days post-hatch (dph) by directly transferring the larvae from its rearing water salinity of 32 ppt to salinities of 10 ppt, 25 ppt, 35 ppt and 45 ppt. Almost all of the larvae subjected to salinity stress dies, hence, it was deemed necessary to examine the influence of handling stress and to determine the age of larvae that could tolerate handling. Larvae of different ages (from 10 dph to 22 dph) were thus subjected to handling stress by collecting them from the mass rearing tank and transferring them to 1000 ml beakers where survival was monitored. Results showed that milkfish larvae were able to withstand handling stress beginning 21 dph. Considering that milkfish fry (21 dph) are already known to tolerate direct transfers to various salinities, the next experiments were focused on pH stress. The suitability reduced or increased pH as stressors were initially tested by directly transferring larvae from normal seawater (pH 7.50) to acidic water (pH 6.5-7.0) and basic seawater (pH 8.0-8.5). Results revealed several advantages of reducing pH levels over increasing pH levels, which included the comparably higher larval survival, the lesser amount of chemicals required to change pH levels and the corresponding cost of these chemicals. A range finding test was then conducted to determine the optimum pH that could selectively remove fry with opercular deformities by directly transferring fry reared in normal seawater (pH 7.50) to seawater with reduced pH: Trt 1-pH 6.5; Trt 2-pH 6.6; Trt 3-pH 6.7; and Trt 4-6.8. Larval mortalities were recorded after 1 h, then 25% water change was done for all treatments which were monitored further for mortalities after 2h, 3h, 5h, and 24h. The surviving larvae from all the treatments were reared further for 18 days (until 40 dph) in order to monitor opercular deformities which can observed only when the larvae have metamorphosed into juveniles. Results showed that a sudden drop in pH of normal seawater to pH 6.5-6.7 selectively removed all the fish with opercular deformities in hatchery produced milkfish seeds; at such pH range, more than 90% survival of milkfish fry was obtained with this batch of larvae and all the surviving fish had no opercular deformities.