博士 / 國立臺灣大學 / 動物學研究所 / 87 / In order to establish the basic aquaculture data for reference of culturist and to provide a model for researching and developing culture technique of new exotic species, a series of relevant experiments have been launched.
An automated system for egg collecting, hatching, and transferring of larvae of several cultured freshwater finfishes has been developed. The system consists of a spawning tank, a filter, an incubation tank, hatching nets, and larviculture ponds. Using this system, grass carp (Ctenopharyngodon idellus), bighead carp (Aristichtys nobilis), silver perch (Bidyanus bidyanus), palmetto bass (Morone saxatilis × M. chrysops) and black carp (Mylopharyngodon piceus) were successfully induced to spawn with a single hormone injection. The fertilized eggs could flow freely into nets for normal hatching, and the hatched larvae could be conveyed automatically into larviculture ponds. The new automated system reduces labor and is highly efficient. The filtration and reuse of culture water achieves the prime objective of water conservation in aquaculture development. The system offers an improvement to the existing technology.
Imported fry of F1 hybrid striped bass (Morone saxatilis × M. chrysops, palmetto bass) were held in an earthen pond and fed exclusively commercial floating pellets. They could reach sexual maturity at 2 years old and could be successfully induced to spawning by a single hormone injection. Fertilization rates ranged from 77.2 to 96.7% and hatch rates were between 1.6 and 24.2%, whereas the level of larval deformities ranged between 19.2 and 100%. The F2 progeny exhibited low hatch rate, low larval survival, high level of deformities, and growth variability which suggests that F2 progeny may not be a suitable candidate species for culture.
An experimental period of 84 days was carried out to examine the effects of three levels of environmental temperature (18, 23 and 28℃) on the growth performance of palmetto bass. Specific growth rate (SGR) and feed intake both increased with increasing temperatures. With increasing temperature, there was a significant decrease in muscle moisture, but an increase in lipid content. The variance in harvest size distribution was much larger at 28℃ than at the lower temperatures. In terms of SGR and FCE, it can be concluded that the most economical temperature for aquaculture of this species is between 23 and 28℃.
Juveniles of palmetto bass were stocked at low (0.71 kg / m3), medium (1.42 kg / m3) and high (2.84 kg / m3) densities. The highest percent weight gain and specific growth rate were obtained in fish raised at medium stocking density and significant differences were found only between low and medium stocking densities. The relationship between proximate composition and growth of fish is less apparent, however, fish with good growth (at medium stocking density) contained more lipid, whereas those with poor growth (at low density) had lower lipid content. The correlation between growth rate and stocking density may be dependent on the factors of social interaction, physical constraints and threshold level of stocking density.
Juveniles palmetto bass were reared for 56 days to compare the performance among the six feeding regimens. The maximum specific growth rate was occurred with group fed three meals daily. The elevation in the feeding frequency resulted in increased food intake but decreased feed conversion efficiency. The total food consumption was higher but quantity of food eaten per feeding was observed to be lower in the fish fed frequently. In addition, body moisture and lipid contents were affected by feeding regimen, whereas protein and ash contents were not. Based on the results of this study, the total amount of food eaten was significantly greater during the day than at night, and the best growth for hybrid striped bass was at three meals daily when food deprivation time was equal to 6 h under the condition used in this study.
Effect of size-sorting on the growth performance of palmetto bass was studied. The results obtained from the present study demonstrated that size-grading did not have a significant effect on harvest total biomass or size-frequency distribution. The coefficient of variation (CV) of the individual weights elevated in both sorted-large and sorted-small fish during the experiment. It is suggested that high levels of social interaction between individuals of similar size might result in developing agonistic behavior, which both interfere with feeding and lead to increase energy expenditure, giving reduced growth as the end result.
Three temperatures (18, 23, and 28℃), three stocking density levels (0.72, 1.42, and 2.84 kg / m3), and two size-groups (averaging 104 and 173 g, respectively) were designed to conduct experiments on the effect of temperature, stocking density, and fish size on the ammonia excretion (AE). As a result, AE increased with increasing temperatures and stocking densities. On the contrary, AE varied inversely with individual fish size. Diurnal variation of AE in palmetto bass showed that AE increased to a peak at about 4 h after feeding was initiated, and to the lowest value at about 24 h.
| Identifer | oai:union.ndltd.org:TW/087NTU00312008 |
| Date | January 1999 |
| Creators | Fu-Guang Liu, 劉富光 |
| Contributors | Hon-Cheng Chen, 陳弘成 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 168 |
Page generated in 0.0016 seconds