碩士 / 國立海洋大學 / 水產養殖學系 / 89 / Abstract
Although the method of hatching and nursing of grouper larvae is almost established, but to maintain a stable survival rate of larvae is still hard. The factors influencing survival rate include water flow, light, water temperature, egg quality, larval behavior, larvae developing characteristics and live foods…etc.
The purpose of this research is to improve the survival rate of early stage larvae of grouper (Epinephelus coioides). The survival rates of larvae in three types of nursery system were investigated. Three types of water flow conditions (aeration、whirlpool and stewing) in nursery tank had been setup and used to test the hatching rate of fertilized eggs and the survival rate of yolk-sac stage larvae. The results showed that the hatching rate in all three facilities was no different significantly (p>0.05), but the survival rate was. The best survival rate (92.5±6.3%) of larvae before first feeding was obtained in whirlpool treatment.
In order to find the maximum density of grouper larvae which could be nursed in whirlpool system, various amounts of fertilized eggs 2.5, 5, 10, 15, 20, 25 and 30 g were put in various tanks with the same water volume (15 l) and nursed until D3. The hatching rate (96.4-97.8 %) between treatments had no significant different (p>0.05). But due to contamination of water quality, larvae after hatching of groups 30, 25 and 20 g died on D1, D2 and D3, respectively, and 1 g/l was the maximum allowable stocking density under the experimental conditions.
In order to solve the problem of larvae death after feeding due to contamination of water quality, the feasibility of the application of the recirculating aquaculture system was investigated, also. At first, the nursery efficiency of recirculating system and stewing (control) system were compared. The results showed that the survival rate (36.5%) and body length (0.5 cm) of larvae in recirculating system were greater than the control (23.5%, 0.3 cm) on D10. Furthermore, the best water exchange rate in nursing tank was investigated. The results showed that the nursery efficiency were not different significantly for daily water exchange rate of 50, 100 and 200 %, while they were all better than system without water exchange.
| Identifer | oai:union.ndltd.org:TW/089NTOU0086007 |
| Date | January 2001 |
| Creators | Da-wai Lan, 藍大為 |
| Contributors | Kuo - Feng Tseng, 曾國鋒 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 51 |
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