Teng, S.-K. and Chua, T.-E., 1979. Use of artificial hides to increase the stocking density and p... more Teng, S.-K. and Chua, T.-E., 1979. Use of artificial hides to increase the stocking density and production of estuary grouper, Epinephelus salmoides Maxwell, reared in floating net cages. Aquaculture, 16: 219-232. The relative growth and production of estuary grouper, Epinephelus salmoides, in response to seven combinations of hiding space and stocking density were studied in floating net cages. Used car tyres were suspended in the net cages to provide hiding space for the fish. The seven combinations of hiding space and stocking density were as follows: Hiding space (cm3/fish): 0116181222251272289 + Stocking density (fish/m"): 60 84108132156180204 Provision of hiding space in the net cages was found to permit an increase in the stocking density from the optimal rate of 60 fish/m3 (without artificial hides) to 156 fish/m3. The net production was found to increase from 8.5 kg/m3 to 19.5 kg/m3 after 3 months. Growth in terms of weight gain per fish, survival rate and food conversion ratio at stocking rates below 156 fish/m" with hiding space between 116 and 222 cm3/fish was comparable to that observed at the optimal stocking density without hiding space (60 fish/m3). The growth of fish stocked at 180-204 fish/m3 with hiding space of 272-289 cm3/fish, respectively, was found to be significantly depressed. Thus, with the provision.of hiding'space of 251 cm3/fish, the stocking density could be increased to as high as 156 fish/m3 and the production of fish could be increased by 230% over that at the usua.I optimal stocking rate of 60 fish/m3 without artificial hides.
The factors affecting production of estuary grouper, Epinephelus salmoides, in floating net cages... more The factors affecting production of estuary grouper, Epinephelus salmoides, in floating net cages are discussed. The concept of economic production in cage culture is outlined. Economic production of estuary grouper could be achieved by providing a suitable culture site with good water quality; ensuring proper farm management and regular maintenance of cages; preventing disease and ensuring efficient treatment; providing optimum stocking density, a balanced diet, optimal feeding frequency; manipulating fish behaviour by providing artificial hides; and manipulating physiological characteristics, e.g. by the use of growth promoters. The paper further describes environmental parameters, such as dissolved oxygen content, water temperature, salinity, water current, bacteria count, pH, and bottom sediments, as important factors in site selection. Their effects on the growth and production of fish are discussed and their optimal levels determined. The problems involving management and maintenance of the farm are also outlined. The main problem in cage culture is fouling which demands considerable labour and money for cage maintenance. Other problems such as predators, poaching, and cannibalism are discussed at length. It is suggested that by manipulation of stocking density, production could be increased. The optimal stocking rate was found to be 60 fish/m3 which gives a high yield of marketable fish. Stocking could be further intensified by providing artificial hides using used car tyres. The net production could be increased by 230% if hiding space of 251 cm' per fish was provided and the stocking density increased to 156 fish/m'. Although formulated feeds enhanced growth by 27.1% over that of groupers fed on trash fish, the production cost was much higher, rendering the use of formulated feeds alone uneconomical for commercial fish culture. Growth promoters such as 17~methyltestosterone and riitrovin have been found to promote growth of young estuary grouper by 43.4 and 62.8%, respectively. Using various combinations of culture techniques, it was shown that net production could be increased from 23.76 kg/m3 using conventional culture methods to 136.7 5 kg/m' with a combination of hiding space, heavy stocking, appropriate feeding frequency and formulated feeds incorporating growth promoters. The production time was also shortened considerably from 6 months to 2.7 months. Cost-benefit analysis of the eight culture techniques tested indicated that the production cost could be reduced from US$2.OO/kg with conventional methods to as low as US$1.28/kg using a sophisticated method. However, based on current market proces, the conventional culture technique was still economically feasible, as the net income over total capital costs was 33.3%. Improvements of the conventional culture technique will increase the ratio of net income over total capital costs by l-3 times.
The effects of food ration on the growth and yield of the estuary grouper raised in floating net-... more The effects of food ration on the growth and yield of the estuary grouper raised in floating net-cages were investigated. The optimum ration given on alternate days was 5% body weight (wet) which gave the best mean fish weight, uniform condition factor with time, relatively good survival rate, and greatest efficiency of food conversion. The maintenance, optimum and maximum food rations were 1.41, 5.75, and 9.0% body weight (wet) respectively. The fish were more uniform in size when fed 5–8% body weight. Though the yields at the end of the experiment were higher with high ration rates, the difference between rations of 5 and 9.1% body weight was 26.8 and 33.6%, whilst that between 5% and 2% body weight was 596%. For economic production, the ration should be approximately 5% of body weight supplied every 2 days.
Studies on the effect of stocking density on the growth of estuary grouper (Epinephelus salmoides... more Studies on the effect of stocking density on the growth of estuary grouper (Epinephelus salmoides) were conducted in floating net-cages. Four stocking densities (15, 30, 60 and 120 fish/m3) and two sizes of fish (26 f 0.2 gm and 15.2 f 0.1 gm) were studied. Results of the present study indicate that fish at the stocking density of 60 fish/m3 grew equally fast and showed comparable food conversion ratio and survival rate as those at lower stocking densities of 15 and 30 fish/m3. The net-yield of fish at a stocking density of 60 fish/m' was 1.9 and 3.5 times that of fish at densities of 30 and 15 fish/m', respectively. However, at 120 fish/m', a remarkable decrease in the weight-gain per fish, mean fish weight, efficiency of food conversion as well as survival rate was recorded. The possible effects of stocking density on the growth of estuary grouper under cageculture conditions were discussed.
... 631 Page 9. Table 3 . Effect of Water Temperature on the Survival and Growth of Brown-Spotted... more ... 631 Page 9. Table 3 . Effect of Water Temperature on the Survival and Growth of Brown-Spotted Grouper Larvae, 0-12 day old. Initial size of larvae stocked, 2.36kO.08 mm; initial stocking density, 60 larvae/liter. ... 634 Page 12. Hussain, N, M. Saif Abdullah, and M. Ukawa. 1975. ...
The ingestion, fecundity, growth rates and culture of the harpacticoid copepod, Tisbe furcata, fe... more The ingestion, fecundity, growth rates and culture of the harpacticoid copepod, Tisbe furcata, fed different algal species at different cell densities were studied. It was found that Tisbe furcata initiated feeding at an algal concentration of 2.5 cells l 1 for Rhinomonas reticulata and 8 cells l 1 for Skeletonema costatum but a higher concentration of 30 cells l 1 was needed for the flagellate, Pavlova lutheri. Although the larval growth rates of T. furcata fed on R. reticulata and S. costatum were similar (P>0.05), they were significantly higher than that of T. furcata fed on P. lutheri (P<0.05). The concentrations of algal diets optimal for the population growth rate of T. furcata varied with algal species as follows: Skeletonema costatum at 80 cells l 1 , Rhinomonas reticulata at 15 cells l 1 and Pavlova lutheri, at 90 cells l 1 .
Husbandry and spawning performance of blue-fin porgy broodstock, Sparidentex hasta (Valenciennes)... more Husbandry and spawning performance of blue-fin porgy broodstock, Sparidentex hasta (Valenciennes), are described. Both wild broodstock (fish caught from the sea and domesticated in tanks) and cultured broodstock (from hatchery-produced fry grown in tanks) spawned spontaneously in large concrete or fiberglass tanks (30–90 m3) during February–April 1987. About 88 million eggs were collected from spawning 36 female and 32 male broodstock of 4–7 years old. A total of 61.3% of the collected eggs were floating (viable) eggs. Average hatching rate of the floating eggs was 78.8%. Larval rearing and fry production procedures for the blue-fin porgy are presented. An average production rate of 2760 fry (0.3 g each)/m3 (range: 1960–3470 fry/m3) with normal swim bladder inflation was achieved from a pilot larval and fry production trial, which was carried out in ten to twenty 4-m3 circular fiberglass tanks. Average survival rate of the 60-day old fry was 10.2% (range: 8.9%–12.3%) at an average initial density of 57 hatched larvae/l. Initial swim bladder inflation rates for 12-day old larvae ranged from 64% to 93% (average, 83%) but increased to an average of 95% for 60-day old fry. Critical stages where high larval mortalities occurred are described. Several modifications were made to the previous larval rearing and fry production procedures in terms of feeding regime and illumination. The modifications may have contributed to the better larval survival and fry production rates as well as higher initial swim bladder rates compared to previous results.
Teng, S.-K. and Chua, T.-E., 1979. Use of artificial hides to increase the stocking density and p... more Teng, S.-K. and Chua, T.-E., 1979. Use of artificial hides to increase the stocking density and production of estuary grouper, Epinephelus salmoides Maxwell, reared in floating net cages. Aquaculture, 16: 219-232. The relative growth and production of estuary grouper, Epinephelus salmoides, in response to seven combinations of hiding space and stocking density were studied in floating net cages. Used car tyres were suspended in the net cages to provide hiding space for the fish. The seven combinations of hiding space and stocking density were as follows: Hiding space (cm3/fish): 0116181222251272289 + Stocking density (fish/m"): 60 84108132156180204 Provision of hiding space in the net cages was found to permit an increase in the stocking density from the optimal rate of 60 fish/m3 (without artificial hides) to 156 fish/m3. The net production was found to increase from 8.5 kg/m3 to 19.5 kg/m3 after 3 months. Growth in terms of weight gain per fish, survival rate and food conversion ratio at stocking rates below 156 fish/m" with hiding space between 116 and 222 cm3/fish was comparable to that observed at the optimal stocking density without hiding space (60 fish/m3). The growth of fish stocked at 180-204 fish/m3 with hiding space of 272-289 cm3/fish, respectively, was found to be significantly depressed. Thus, with the provision.of hiding'space of 251 cm3/fish, the stocking density could be increased to as high as 156 fish/m3 and the production of fish could be increased by 230% over that at the usua.I optimal stocking rate of 60 fish/m3 without artificial hides.
The factors affecting production of estuary grouper, Epinephelus salmoides, in floating net cages... more The factors affecting production of estuary grouper, Epinephelus salmoides, in floating net cages are discussed. The concept of economic production in cage culture is outlined. Economic production of estuary grouper could be achieved by providing a suitable culture site with good water quality; ensuring proper farm management and regular maintenance of cages; preventing disease and ensuring efficient treatment; providing optimum stocking density, a balanced diet, optimal feeding frequency; manipulating fish behaviour by providing artificial hides; and manipulating physiological characteristics, e.g. by the use of growth promoters. The paper further describes environmental parameters, such as dissolved oxygen content, water temperature, salinity, water current, bacteria count, pH, and bottom sediments, as important factors in site selection. Their effects on the growth and production of fish are discussed and their optimal levels determined. The problems involving management and maintenance of the farm are also outlined. The main problem in cage culture is fouling which demands considerable labour and money for cage maintenance. Other problems such as predators, poaching, and cannibalism are discussed at length. It is suggested that by manipulation of stocking density, production could be increased. The optimal stocking rate was found to be 60 fish/m3 which gives a high yield of marketable fish. Stocking could be further intensified by providing artificial hides using used car tyres. The net production could be increased by 230% if hiding space of 251 cm' per fish was provided and the stocking density increased to 156 fish/m'. Although formulated feeds enhanced growth by 27.1% over that of groupers fed on trash fish, the production cost was much higher, rendering the use of formulated feeds alone uneconomical for commercial fish culture. Growth promoters such as 17~methyltestosterone and riitrovin have been found to promote growth of young estuary grouper by 43.4 and 62.8%, respectively. Using various combinations of culture techniques, it was shown that net production could be increased from 23.76 kg/m3 using conventional culture methods to 136.7 5 kg/m' with a combination of hiding space, heavy stocking, appropriate feeding frequency and formulated feeds incorporating growth promoters. The production time was also shortened considerably from 6 months to 2.7 months. Cost-benefit analysis of the eight culture techniques tested indicated that the production cost could be reduced from US$2.OO/kg with conventional methods to as low as US$1.28/kg using a sophisticated method. However, based on current market proces, the conventional culture technique was still economically feasible, as the net income over total capital costs was 33.3%. Improvements of the conventional culture technique will increase the ratio of net income over total capital costs by l-3 times.
The effects of food ration on the growth and yield of the estuary grouper raised in floating net-... more The effects of food ration on the growth and yield of the estuary grouper raised in floating net-cages were investigated. The optimum ration given on alternate days was 5% body weight (wet) which gave the best mean fish weight, uniform condition factor with time, relatively good survival rate, and greatest efficiency of food conversion. The maintenance, optimum and maximum food rations were 1.41, 5.75, and 9.0% body weight (wet) respectively. The fish were more uniform in size when fed 5–8% body weight. Though the yields at the end of the experiment were higher with high ration rates, the difference between rations of 5 and 9.1% body weight was 26.8 and 33.6%, whilst that between 5% and 2% body weight was 596%. For economic production, the ration should be approximately 5% of body weight supplied every 2 days.
Studies on the effect of stocking density on the growth of estuary grouper (Epinephelus salmoides... more Studies on the effect of stocking density on the growth of estuary grouper (Epinephelus salmoides) were conducted in floating net-cages. Four stocking densities (15, 30, 60 and 120 fish/m3) and two sizes of fish (26 f 0.2 gm and 15.2 f 0.1 gm) were studied. Results of the present study indicate that fish at the stocking density of 60 fish/m3 grew equally fast and showed comparable food conversion ratio and survival rate as those at lower stocking densities of 15 and 30 fish/m3. The net-yield of fish at a stocking density of 60 fish/m' was 1.9 and 3.5 times that of fish at densities of 30 and 15 fish/m', respectively. However, at 120 fish/m', a remarkable decrease in the weight-gain per fish, mean fish weight, efficiency of food conversion as well as survival rate was recorded. The possible effects of stocking density on the growth of estuary grouper under cageculture conditions were discussed.
... 631 Page 9. Table 3 . Effect of Water Temperature on the Survival and Growth of Brown-Spotted... more ... 631 Page 9. Table 3 . Effect of Water Temperature on the Survival and Growth of Brown-Spotted Grouper Larvae, 0-12 day old. Initial size of larvae stocked, 2.36kO.08 mm; initial stocking density, 60 larvae/liter. ... 634 Page 12. Hussain, N, M. Saif Abdullah, and M. Ukawa. 1975. ...
The ingestion, fecundity, growth rates and culture of the harpacticoid copepod, Tisbe furcata, fe... more The ingestion, fecundity, growth rates and culture of the harpacticoid copepod, Tisbe furcata, fed different algal species at different cell densities were studied. It was found that Tisbe furcata initiated feeding at an algal concentration of 2.5 cells l 1 for Rhinomonas reticulata and 8 cells l 1 for Skeletonema costatum but a higher concentration of 30 cells l 1 was needed for the flagellate, Pavlova lutheri. Although the larval growth rates of T. furcata fed on R. reticulata and S. costatum were similar (P>0.05), they were significantly higher than that of T. furcata fed on P. lutheri (P<0.05). The concentrations of algal diets optimal for the population growth rate of T. furcata varied with algal species as follows: Skeletonema costatum at 80 cells l 1 , Rhinomonas reticulata at 15 cells l 1 and Pavlova lutheri, at 90 cells l 1 .
Husbandry and spawning performance of blue-fin porgy broodstock, Sparidentex hasta (Valenciennes)... more Husbandry and spawning performance of blue-fin porgy broodstock, Sparidentex hasta (Valenciennes), are described. Both wild broodstock (fish caught from the sea and domesticated in tanks) and cultured broodstock (from hatchery-produced fry grown in tanks) spawned spontaneously in large concrete or fiberglass tanks (30–90 m3) during February–April 1987. About 88 million eggs were collected from spawning 36 female and 32 male broodstock of 4–7 years old. A total of 61.3% of the collected eggs were floating (viable) eggs. Average hatching rate of the floating eggs was 78.8%. Larval rearing and fry production procedures for the blue-fin porgy are presented. An average production rate of 2760 fry (0.3 g each)/m3 (range: 1960–3470 fry/m3) with normal swim bladder inflation was achieved from a pilot larval and fry production trial, which was carried out in ten to twenty 4-m3 circular fiberglass tanks. Average survival rate of the 60-day old fry was 10.2% (range: 8.9%–12.3%) at an average initial density of 57 hatched larvae/l. Initial swim bladder inflation rates for 12-day old larvae ranged from 64% to 93% (average, 83%) but increased to an average of 95% for 60-day old fry. Critical stages where high larval mortalities occurred are described. Several modifications were made to the previous larval rearing and fry production procedures in terms of feeding regime and illumination. The modifications may have contributed to the better larval survival and fry production rates as well as higher initial swim bladder rates compared to previous results.
Uploads
Papers by Seng-Keh Teng