Egg collection and biotelemetry studies of tiger grouper, Epinephelus fuscoguttatus in broodstock tank

Ha , Hou Chew (2007) Egg collection and biotelemetry studies of tiger grouper, Epinephelus fuscoguttatus in broodstock tank. Masters thesis, University Malaysia Sabah.

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Abstract

This study was performed to get basic knowledge of egg collection in tiger grouper, Epinephelus fuscoguttatus through natural spawning in a 150-ton broodstock tank. The chosen 18 E. fuscoguttatus were transferred from the net cage into the broodstock tank. Water quality (temperature, dissolved oxygen, pH and salinity) was measured twice per day and the E. fuscoguttatus were fed with trash fish. An egg net was set up in the broodstock tank to collect the eggs of E. fuscoguttatus every month. Biotelemetry experiment on E. fuscoguttatus was conducted to measure the depth where the fish stayed in the broodstock tank and the fish body temperature to understand their behaviour during spawning. Data loggers were able to record the water depth and the temperature at 2-minute intervals continuously for 30 days. Data loggers were inserted into the abdomen of a female and a male. Approximately 105 million eggs were collected from July 2004 until October 2004. Spawning occurred in July (46 million eggs), August (24 million eggs) and October (35 million eggs) 2004. The biggest egg diameter (0.880 mm) with the highest fertilization rate (95.2%) was considered the best egg quality among the 3 spawnings. The fertilization rate of this study was considerably higher than other studies, which seemed to be because of the water depth of the broodstock tank. In each spawning period, E. fuscoguttatus spawned for 5-6 consecutive nights in the broodstock tank. The spawning occurred at midnight (11pm-1am). On the other hand, from the water parameter results, spawning could occur at 27.4 °C ± 1.1°C (mean ± SD), dissolved oxygen 6.26 mg/L ± 0.41 mg/L, salinity 31.4 ppt ± 0.9 ppt and pH 7.88 ± pH 0.19. On average, the females swam to the water surface between 1.2 times/night and 3.8 times/night during the spawning periods. However, it was only 0.6 times/night during the non-spawning periods. The results of the data logger show E. fuscoguttatus spawned at the water surface with an extreme changes of body temperature. From this study, the 150-ton broodstock tank with 3m depth is suitable for the egg collection of E. fuscoguttatus through natural spawning. This broodstock tank system and management, such as the water temperature 24.4-31.7 °C, the salinity 30-33 ppt, the DO 5.03-6.97 mg/L, the pH 7.32-8.37 and the mean of feeding rate 1.8%, can be recommended as a guideline to other hatcheries for the constant collection of E. fuscoguttatus eggs. The data logger is introduced as a new tool to improve the understanding on fish behaviour, in order to develop the aquaculture in Malaysia.

Item Type:Thesis (Masters)
Uncontrolled Keywords:egg collection, tiger group, Epinephelus fuscoguttatus, spawning, brood stock tank, water quality, aquaculture
Subjects:Q Science > QL Zoology
Divisions:SCHOOL > Borneo Marine Research Institute
ID Code:9132
Deposited By:IR Admin
Deposited On:09 Jul 2014 09:34
Last Modified:09 Jul 2014 09:34

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