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1.
Eggs and sperm were obtained from a female (6.3 kg/BW) and a male (8.4 kg/BW) longtooth grouper Epinephelus bruneus following HCG injection in July 2003. The eggs were fertilized artMcially with the sperm and incubated in one of two 50-m3 tanks after washing the fertilized eggs. The fertilized eggs were 830–950 pn (average 900 ± 2 μm) in diameter and the respective fertilization and hatching rates were 97.7 ± 0.6% and 96.8 ± 0.5% at a water temperature of 25.0 ± 0.5 C. With this regime, the survival rate by day 93 was 7.5% in the 50-m3 tank. The elapsed time from hatching to opening the mouth was 3 d at 25 C. The initial mouth size (z) of the larvae was 0.22–0.23 mm. The newly hatched larvae were 2.02 ± 0.02 mm TL; this increased to 4.12 ± 0.09 mm TL by day 11. By day 54, the larvae had metamorphosed into juveniles and reached 41.12 ± 1.20 mm TL, and by day 93 the juveniles reached 93.78 ± 1.98 mm TL. In all, 49.5% of the larvae were malformed and the type of malformation was diverse.  相似文献   

2.
Abstract. Effects of stocking density on water quality and on the growth, survival and food conversion of Oreochromis niloticus (Linnaeus) were evaluated. Fingerlings of tilapia (average weight 40.25 ± 94 g) were stocked in six 3.75-m3 concrete tanks at 16, 32 and 42.6/m3 and reared for 164 days. A water flow rate of 1 l/min/kg fish biomass was maintained in all the tanks. The growth rate was inversely related to stocking density with mean weights of 337.25g, 327.0g and 323.5g at the low, medium and high densities respectively. At harvest, standing crop biomass averaged 5.36 kg, 10.44kg and 13.24kg for the three densities. The respective food conversion ratios (FCR) were 1.85, 1.88 and 1.95, while the survival rates were 99.2, 99.6 and 95.9%. However, the survival rate, growth rate and food conversion efficiencies were not significantly different at the three stocking densities. Water quality did not deteriorate in different tanks as the oxygen was continuously replenished and metabolites and waste products removed by the water flowing through the tanks. These data suggest that culture of tilapia at a density of 42.6/m3 and production of 13.24 kg/m3 in 164 days with a production of 18–20 kg/m3 in a growing season (April-October) of 210 days is possible using the drainage water in flow-through water systems.  相似文献   

3.
Abstract.— Two spawning and larval rearing trials with striped patao Eugerres brasilianus were conducted at Tunas de Zaza, Cuba, to develop a method for experimental-scale mass production of juvenile fish. Mature striped patao were captured from coastal lagoons in September 1988 and January 1989. Sexually mature females and males were induced to spawn by treatment with human chorionic gonadotropin (HCG). After spawning, eggs were collected and placed in 1.2-m3 cylindroconical fiberglass incubators at densities of 150 and 200 eggs/L. About 1 h before hatching, eggs were transferred to 5–m3 concrete tanks. Larvae were fed a mixture of marine microalgae, rotifers, copepods, and Artemia nauplii; artificial food was supplied at 30 d post-hatch as a shrimp diet with 25% protein and 0.1–0.4 mm particles. Fourteen of 20 females spawned after 2 or 3 HCG injections (total dose = 6–10 IU/g body weight). Fecundity was 467–2,167 eggs/g body weight. Egg incubation time in seawater (38–39 ppt salinity) was 15–17 h at 29–30 C and 21–23 h at 25–26 C, with 98–100% hatching rate. The oil droplet and yolk sac were consumed by 3 to 5 d post-hatch and first food (rotifers) was eaten during second day. High larval mortalities began after the first month. Growth in 39- ppt seawater was faster (0.41 ± 0.01 md/d) at 29.1 ± 0.3 C than at 25.2 ± 0.2 C (0.27 ± 0.008 mm/d). Overall survival was 6–12.5% with tinal densities of 5–10 juveniles/L after 48–60 d. A total of 132,000 juveniles was harvested from the two rearing cycles.  相似文献   

4.
Abstract This study was conducted to evaluate the effects of stocking density and monosex culture on growth, survival, yield and feed conversion ratio of freshwater prawn Macrobrachium rosenbergii in concrete tanks. Juvenile prawns with an average weight of 1.8 g were stocked into triplicate tanks at densities of 5, 10, 15 and 20 prawns/m2, grown for 168 d and fed a 34% tilapia diet. Stocking density had significant effect on prawns. Final mean body weight decreased with the increasing density, being highest at 5 prawns/m2 (29.6 9). and lowest at 20 prawns/m2 (17.4 g). Total yield increased from 135 g/m2 (1,350 kg/ha) at a density of 5 prawns/m2 to 261 g/m2 (2,610 kg/ha) at density 15/mz to 245 g/m2 (2,450 kg/ha) at 20/mz. Feed conversion ratios were high and ranged from 3.7 (5 prawns/m2) to 5.6 (20 prawns/m2).
In monosex culture of freshwater prawns stocked in triplicate tanks at a density of 5 prawns/m2 for 112 d, the all-male population had the best growth performance and feed conversion ratio, followed by the mixed-sex and all-female populations. The all-male population had 99% marketable prawns (>20 g) with an average yield of 159 g/m2 (1,590 kg/ha); the mixed-sex population had 90% marketable prawns and the yield was 135 g/mz (1,350 kg/ha); and the all-female population had 75% marketable prawns with an average yield of 108 g/m2 (1,080 kgha).  相似文献   

5.
A two-factor experiment was carried out to investigate the change in skin colour and plasma cortisol response of cultured Australian snapper Pagrus auratus to a change in background colour. Snapper (mean weight=437 g) were held in black or white tanks and fed diets containing 39 mg unesterified astaxanthin kg−1 for 49 days before being transferred from white tanks to black cages (WB) or black tanks to white cages (BW). Skin colour values [ L * (lightness), a * (redness) and b * (yellowness)] of all snapper were measured at stocking ( t =0 days) and from cages of fish randomly assigned to each sampling time at 0.25, 0.5, 1, 2, 3, 5 and 7 days. Plasma cortisol was measured in anaesthetized snapper following colour measurements at 0, 1 and 7 days. Fish from additional black-to-black (BB) and white-to-white (WW) control treatments were also sampled for colour and cortisol at those times. Rapid changes occurred in skin lightness ( L * values) after altering background colour with maximum change in L * values for BW and WB treatments occurring within 1 day. Skin redness ( a *) of BW snapper continued to steadily decrease over the 7 days ( a *=7.93 × e−0.051 × time). Plasma cortisol concentrations were highest at stocking when fish were held at greater densities and were not affected by cage colour. The results of this study suggest that transferring dark coloured snapper to white cages for 1 day is sufficient to affect the greatest benefit in terms of producing light coloured fish while minimizing the reduction in favourable red skin colouration.  相似文献   

6.
Abstract— Wild-caught, adult summer flounder Paralichthys dentatus (avg. wt. = 740 g; range = 264–1,540 g; N = 60), collected in northeastern US coastal waters during October 1994, were transported to Vero Beach, Florida in March 1995 and held in 2.6-m3 indoor tanks through November 1995 under two artificial photothermal regimes: (1) natural regime, simulating natural habitat conditions; and (2) accelerated thermal regime, with seasonal temperature changes advanced by one month. A third group of fish was held in outdoor tanks under ambient photothermal conditions. Under all photothermal conditions, onset of vitellogenesis was associated with declining daylength and temperature, beginning in the accelerated group, then progressing to the natural and the ambient groups. From 20 September to 28 November 1995, 23 vitellogenic stage females from the accelerated and natural regimes were implanted with a cholesterol-cellulose pellet containing LHRH-a (100 μg/kg body wt). Females with initial mean oocyte diameters ranging from 258–456 μm spawned voluntarily 2.5–5.5 d postimplantation, while no maturational response was obtained from females with mean diameters ranging from 165–231 μm. Two females were spawned twice during the study period by LHRH-a pellet implantation. Infrequent, natural spawning without hormone intervention was also obtained. Females released from 22.7–396.9 × 103 eggs on the first day of spawning, with fertilization and hatching rates of 0–93.470 and 0–81.1%, respectively.  相似文献   

7.
Abstract.
The study was conducted to develop guidelines for high-density overwintering of tilapia in tanks using warm underground sea water. Seawater-acclimated fish of 20 g were stocked in 36 tanks at 250, 500 and 750/m3. Water flow was regulated at 0.1 and 0.2 l/kg fish/min. Fish were fed at the rates of 0.75% and 1.0% of biomass per day.
After 135 culture days, the mean individual weight gain and specific growth rate decreased, whereas feed conversion increased significantly ( P <0.0001) with the increase in stocking density. The condition factor at 500 and 750 fish/m3 was significantly lower ( P <0.0005) than at 250 fish/m3. However, stocking density had no significant effect on the survival rate. Significantly better specific growth rate, condition factor and feed conversion were observed at a water flow rate of 0.2 l/kg fish/min than at 01 l/kg fish/min. Significantly higher mean individual weight gain, specific growth rate, and survival rate were observed at 1.0%/day than at the 0.75%/day feeding rate. The findings indicate that the optimum stocking density for overwintering tilapia in tanks using warm underground sea water is 750 fish/m3 with a water flow rate of 0.1 l/kg fish/min and a feeding rate of 0.75%/day.  相似文献   

8.
Abstract. Production of Florida red tilapia seed (eggs, sacfry and fry) in 34-m2 above-ground tanks using recirculated brackishwater (12 ppt) was studied over a 5-month period on Lee Stocking Island (Exuma Cays, Bahamas). Four tanks were stocked with year class 1 (YCI) breeders, while 2 tanks were stocked with year class 2 (YCII) breeders at densities of 200 and 240/tank (5·9 and 7·1/m2), respectively, and at a sex ratio of 3 females to 1 male, beginning in November 1988. Seed production was measured by removing free-swimming fry from tanks and eggs and sacfry from the mouths of brooding females, and assessing the number of each at 15 to 16-day intervals from February to June 1989. Average seed production (seed/m2/day) was significantly higher in YCI (52·3) than in YCII (36·0) broodstock, indicating the advantages of replacing broodstock with yearling breeders each year.  相似文献   

9.
Intensive Culture Potential of Penaeus vannamei   总被引:3,自引:0,他引:3  
Tank and pond rearing studies were conducted to assess the potential for intensive culture of Penaeus vannamei in South Carolina. Postlarvae were stocked in intensive nursery tanks at 500/ m2. Growth and survival were compared for shrimp reared in control fiberglass tanks and in tanks with artificial substrates (fiberglass screen). Addition of substrate improved survival (82% versus 58%), but not growth. Juvenile shrimp (mean weight, 1.3 g) from the nursery trial were stocked into 6 m diameter tanks at densities of 10, 20 and 40/m2. Growth rate was inversely related to stocking density, with mean sizes of 33.9, 32.5, and 26.7 g attained at the low, medium, and high densities respectively after 168 days. At harvest, standing crop biomass averaged 225.6, 442.0, and 685.4 g/m2 for the three densities. To further test the intensive culture potential, two 0.1 ha ponds were stocked with hatchery-reared postlarvae at densities of approximately 40 and 45/m2. The ponds were managed intensively using paddlewheel aerators and water exchange averaging 16–17%/day. The ponds were harvested after 138 and 169 days and yielded 6,010 kg/ha of 16.7 g (mean weight) shrimp and 7,503 kg/ha of 17.9 g shrimp, respectively. Average production was 6,757 kg/ha with a food conversion of 2.51. These data suggest good potential for intensive pond culture of P. vannamei in South Carolina and other areas of the continental United States.  相似文献   

10.
Abstract— Grow-out performance of striped bass Morone saxatilis , palmetto bass ( M. saxatilis ♀ × M. chrysops ♂ ) and backcross hybrids [sunshine bass ♀( M. chtysops ♀ × M. saxatilis ♂) × M. saxatilis ♂] was examined in a two-part study. During part I fish (mean weight = 20.1 g) were stocked at a density of 56 fish/m3 in 1.8-m3 cylindrical fiberglass tanks connected to a central biological filter. Fish were fed a 38% protein trout ration daily and the study duration was 273 d. At harvest, no differences ( P > 0.05) in mean weight or feed conversion were detected among the fish types. However, there were differences in specific growth, with the striped bass having a significantly higher growth rate than the palmetto bass and the backcross hybrids being intermediate. The condition factor (K) for striped bass was also significantly lower (1.2) than that recorded for either of the other two groups. In addition, survival of striped bass (91%) was significantly higher than that of backcross hybrids (74%), while survival of palmetto bass (87%) was intermediate. The survival of backcross hybrids was adversely impacted by an infestation of the dinoflagellate Amyloodinium sp . During part II stocking density in each tank was reduced to 19 fish/m3. The study lasted 104 d. At harvest, no differences were detected in weight, survival, or feed conversion. However, there were significant differences in specific growth, length and K. Striped bass and backcross hybrids gained weight faster than palmetto bass. Length and K were inversely related with all groups being significantly different. Striped bass had the largest TL and the lowest K while, palmetto bass were the shortest with the highest K.  相似文献   

11.
The effects of four levels of diffused aeration (0, 6, 12, and 24 hours/day) and two stocking densities (400 and 600 fish/m3) on the culture performance of caged Florida red tilapia were evaluated in 1 m3 cages in a 2 ha watershed pond on St. Croix, U.S. Virgin Islands. Fish obtained a nutritionally-complete (36% protein), floating feed from demand feeders for 143 to 146 days. Diffused aeration had no significant ( P > 0.05) effect on fish growth, survival, feed conversion, and production in cages. Combined across all levels of diffused aeration, fish stocked at 400/cage had a greater growth rate (2.21 vs. 1.97 g/day), larger final body weight (370 vs. 335 g), and a lower feed conversion ratio (1.69 vs. 1.80) than fish stocked at 600/cage ( P < 0.05). The final biomass of fish stocked at the higher density (181 kg/m3) was greater than at the lower density (140 kg/m3). The enhancement of water exchange rates by diffused aeration did not increase tilapia growth rate or production in cages.  相似文献   

12.
Four diets (T0–T3) were formulated reducing the fishmeal (Indian) component by 100 g kg–1 from 300 to 0 g kg–1 and including proportionately increasing quantities of maize. Diets were fed for 120 days at 50 g kg–1 body weight to triplicate groups of common carp (av. wt. 2.11–2.18 g) stocked at 1 m–2 in mud bottomed cement tanks (18 m2), fertilized with poultry manure. Fish growth, SGR and FCR in the different treatments were statistically not significantly different ( P  > 0.05). PER was lowest for the 300 g fishmeal kg–1 diet treatment (diet T0), increasing with decrease in dietary fishmeal content (diets T1–T3). Fish survival ranged from 96.29 to 100%. Diets influenced carcass composition and digestive enzyme activity. A significant increase in lipid deposition was recorded with increasing dietary carbohydrate content. Amylase, protease and lipase activities were higher in fish fed with diets T2 and T3. The protein sparing effect of dietary carbohydrate and the economic implication of eliminating fishmeal from the diet are discussed.  相似文献   

13.
Abstract.— The effect of stocking prawns Macrobrachium rosenbergii at increasing densities in ponds with Nile tilapia Oreochromis niloticus reared at low density was evaluated. Twelve 0.01-ha earthen ponds were stocked with 1 tilapia/m2 and 0, 2, 4, or 6 postlarvae prawn/m2. Three replicates were randomly assigned to each prawn density. Postlarval prawns were stocked a week prior to tilapia juveniles and both were harvested 175 d after the beginning of the experiment. Tilapia final average weight, survival, production, and food conversion rates did not differ significantly among treatments ( P > 0.05); the averages were 531 g, 67%. 3,673 kg/ha, and 1.91, respectively. Prawn survival rates did not differ for the three stocking densities (mean 90%). However, final weight and production were significantly different ( P < 0.05) as follows: 34.0, 23.0, and 14.7 g and 639, 909, and 818 kg/ha, respectively for 2. 4, and 6 prawns/m2 densities. Stocking densities up to 6 prawn/m2 did not affect tilapia production and required neither additional feeding nor significant changes in management. The polyculture system allowed an increase in total production with the same amount of supplied feed, thus improving the system sustainability.  相似文献   

14.
Abstract— Australian red claw crayfish Cherax quudricarinurus were cultured in monoculture and in polyculture with male Nile tilapia Oreochromis niloricus in nine 0.02-ha earthen ponds. Red claw with an average weight of 7 g were stocked in all ponds at 2/ m2. Tilapia with an average weight of 19 g were stocked in six ponds at either 0.5 or 1/m2. A sinking 32% fish diet and dry alfalfa hay was provided to all ponds as feed and forage. After 135 d, red claw survival was similar (19–24%) in all treatments while average weights were 76 g in monoculture and 48 g in both polyculture treatments. Lower than expected survival was a result of stress caused by poor shipping conditions. Tilapia survivals were similar (84–90%) in all ponds and had an average weight of 403 g when stocked at 1/m2 and 444 g when stocked at 0.5/m2. Red claws are generally considered non-aggressive, especially when compared with other clawed crustaceans. This lack of aggressiveness is suggested as a cause for decreased growth in polyculture with tilapia.  相似文献   

15.
Abstract. Six groups of tropical freshwater catfish, Mystus nemurus (Cuvier & Valenciennes)(mean weight. 20·45 ± l·5g), were reared in 0·34m3 fibreglass tanks at different stocking densities (105, 195, 285, 375, 465 and 555 specimens/m3 water) for 84 days. The objective of the study was to determine the effect of various stocking densities on the growth, nutrition, biochemical composition and survival of M. nemurus. The lowest growth rate appeared in fish at the highest density and the highest was observed in fish stocked in moderate density of 285 and 375 fish/m3 water. Fish production was also lower at relatively low stocking densities of 105 and 195 fish/m3. Food conversion ratio (FCR), protein efficiency ratio (PER) and biochemical composition of M. nemurus indicate that there exists an optimum stocking density which lies between 285 and 375 fish/m3.  相似文献   

16.
Postlarvae of Litopenaeus vannamei were acclimated and stocked in lake-based cages at the following stocking densities: 10, 20, 30 and 40 shrimp m−2. Another set of shrimp was stocked in concrete tanks as reference samples at 30 shrimp m−2. Significant differences were observed among stocking densities throughout the 95-day culture. The final weight at harvest decreased with increasing stocking density: mean weights of 23.3, 15.8, 13.0, 10.9 and 14.6 g for the 10, 20, 30, 40 shrimp m−2 and reference tanks were observed respectively. There were no significant differences in survival throughout the culture period, ranging between 69% and 77%. Daily growth rates (range: 0.11–0.24 g day−1) and specific growth rates (range: 3.54–4.34%) also differed significantly among stocking densities, both increasing with decreasing stocking density. The feed conversion ratio in the cages did not differ among the stocking densities, ranging from 1.53 to 1.65. The relationship between stocking density and mean individual weight at harvest followed the equation y =81.06 x −0.54 ( R 2=0.938) and that of stocking density and production (in g m−2) is y =58.01 x −0.46 ( R 2=0.834).  相似文献   

17.
The results of two stocking density trials on the nursery and grow-out stages of Epinephelus tauvina (Family: Serranidae), in PVC-lined raceways are presented.
At the nursery stage, fry of 17.1 g initial mean weight showed no significant differences in growth rate, survival rate and condition factor when stocked at densities of 200 and 400 fish/m3 over a period of 52 days. Fish grew to mean weights of 61.7 and 63.7 g, giving growth rates of 0.86 and 0.90 g/fish/day and final biomasses of 12.1 and 2S.2 kg/m3 for densities of 200 and 400 fish/m3, respectively. Survival rates were excellent for both treatments at 98percnt; or greater. Food conversion efficiency was slightly improved at the higher density.
At the grow-out stage, E. tauvina of mean weights ranging from 150-170 g cultured for a period of 215 days grew better at a density of 5 fish/m3 than at densities of 20 and 60 fish/m3 (final size: 770, 560 and 450 g with growth rates of 2.8, 1.8 and 1.4 g/fish/day, respectively). Survival rates were higher at the two lower densities. Overall, total biomass increased with stocking density (3.9, 11.1 and 23.4 kg/m3, for 5, 20 and 60 fish/m3, respectively). These results indicate that hamoor has potential to be successfully cultured in raceways.  相似文献   

18.
Rohu, Labeo rohita (Ham.), fingerlings (average wt 3.38 g) maintained in 25 m2 cement tanks were fed fish-meal-based, 300 g kg−1 protein diets containing different levels (0, 0.25, 0.5, 0.75 and 1.0 g kg−1) of L -carnitine in triplicate over a period of 126 days. Fish that received 0.5 g kg−1 carnitine showed significantly higher growth than those fed the basal diet or the rest of the carnitine diets. Fat digestibility, food conversion efficiency and protein efficiency ratio were better in carnitine-fed fish; however, viscerosomatic and hepatosomatic indices decreased. Muscle proximate composition was affected as a result of carnitine treatment. The results of the present study demonstrate a positive effect of carnitine on the growth and body composition of rohu.  相似文献   

19.
Reproductive performance of albino and pigmented channel catfish ( Ictalurus punctarus ) females was compared when spawning was induced with HCG (human chorionic gonadotropin) or Ovaprim 3 (domperidone and [d-Ala6, Pro9 NEt]-luteinizing hormone-releasing hormone). In 1985, only HCG was used to induce spawning. Albino females required more injections, had a longer latency period from time of first injection to spawning, and had lower spawning success (30%) than pigmented females (77%). No differences were observed between albino and pigmented females for time-of-day of spawning, number of eggs obtained by manual stripping, and number of eggs/kg body weight. In 1988, HCG, Ovaprim, and saline (control) were used to induce spawning. HCG induced spawning in 80% of albino and 71% of pigmented females. Ovaprim induced 67% of pigmented females to spawn, but only 2 of 5 albino females spawned. One of four pigmented females injected with saline spawned. Albino females yielded 40–50% fewer eggs/kg body weight than pigmented females. Other performance characteristics for albino and pigmented females were similar whether injected with HCG or Ovaprim. High temperatures encountered during the 1985 spawning season my have had a differential effect on albino and pigmented fish and may account for some differences in spawning success.  相似文献   

20.
An indoor aquaponic system (i.e., the integration of fish culture with hydroponic plant production in a recirculating setup) was operated for maximizing water reuse and year-round intensive food production (Nile tilapia, Oreochromis niloticus , and leaf lettuce) at different fish feed to plants ratios. The system consisted of a fish culture component, solid removal component, and hydroponic component comprising six long channels with floating styrofoam rafts for holding plants. Fish culture effluents flowed by gravity from the fish culture component to the solid removal component and then to the hydroponic component. Effluents were collected in a sump from which a 1-horsepower in-line pump recirculated the water back to the fish culture tanks at a rate of about 250 L/min. The hydroponic component performed as biofilter and effectively managed the water quality. Fish production was staggered to harvest one of the four fish tanks at regular intervals when fish attained a minimum weight of 250 g. Out of the total eight harvests in 13 mo, net fish production per harvest averaged 33.5 kg/m3 of water with an overall water consumption of 320 L/kg of fish produced along with the production of leaf lettuce at 42 heads/m2 of hydroponic surface area. Only 1.4% of the total system water was added daily to compensate the evaporation and transpiration losses. A ratio of 56 g fish feed/m2 of hydroponic surface effectively controlled nutrient buildup in the effluents. However, plant density could be decreased from 42 to 25–30 plants/m2 to produce a better quality lettuce.  相似文献   

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