Simon C. Ellis

Effects of dietary lipid and carbohydrate levels on growth and body composition of juvenile red drum, Sciaenops ocellatus.

Juvenile red drum (2.9 ± 0.3 g) were led one of six experimental diets (containing fish meal, crab meal, fish oil, wheat middlings, mineral and vitamin supplements, cellulose filler and binder) that provided 32% crude protein and 6 or 10% lipid, at three gross-energy (GE) levels ( 15.8 ± 0.3,17.1 ± 0.2 and 18.7± 0.3 kJ/g). Dietary carbohydrate (NFE) levels ranged from 24 to 39%. Significantly (P < 0.05) higher weight gain (481%), feed efficiency (FE: 0.375), apparent net protein retention (ANPR: 19.77%) and apparent net energy retention (ANER: 10.81%) were associated with a diet containing 16.1 kJ GE/g, 10% lipid and 24% NFE. Survival (71–88%) did not differ significantly among dietary treatments. Weight gain, FE, ANPR and ANER of red drum was inversely related to dietary energy level and dietary carbohydrate content. Body lipid levels were significantly (P < 0.05) higher in fish fed 10% lipid diets than in those fed 6% lipid. Dietary lipid exhibhted greater proteinsparing action than dietary carbohydrate, at all energy levels tested. The ability of juvenile red drum to utilize dietary carbohydrate as an energy source may be limited in comparison with warnwater omnivorous species like channel catfish and common carp.

Effects of dietary soybean and fish-protein ratios on growth and body composition of red drum (Sciaenops ocellatus) fed isonitrogenous diets.

An 8-week growth trial was conducted with red drum (Sciaenops ocellatus) to determine the amount of soybean protein that could be substituted for fish protein in formulated diets without reducing growth. In the laboratory, juvenile red drum (7.4 ± 0.1 g) were fed 34%-crude-protein diets in which dietary protein was supplied by soybean (soy) meal, menhaden fish meal or an isonitrogenous mixture of soybean and fish meal calculated to provide graded levels of each protein source. Dietary protein was provided as: (1) 100% soy protein; (2) 100% soy protein with a methionine supplement (calculated to approximate the methionine content of menhaden fish meal); (3) 75% soy protein: 25% fish protein; (4) 50% soy protein: 50% fish protein, (5) 25% soy protein: 75% fish protein; and (6) 100% fish protein. Diets containing only soy protein or soy protein plus a methionine supplement were poorly consumed by red drum. Approximately half of the fish that received these diets died during the first 4 weeks of the growth trial and the remainder lost weight. The 100%-soy and 100%-soy + methionine diets were therefore considered unacceptable for practical use and both treatments were terminated after 4 weeks. Among the remaining treatment groups, red drum fed diets containing only fish protein (100 FP), or soy-protein: fish-protein (SP: FP) ratios of 1: 3 (25 SP: 75 FP) and 1: 1 (50 SP: 50 FP) had higher (P 0.05) from that of fish fed the diets with higher levels of fish protein. This indicated a superior cost: benefit ratio for the 1:1 soy-protein: fish-protein mixture in a 34%-crudeprotein diet for fingerling red drum.

Progress in controlled breeding of Nassau grouper (Epinephelus striatus) broodstock by hormone induction

Abstract Human chorionic gonadotropin (HCG), luteinizing hormone-releasing hormone analogue (LHRH-a), and carp pituitary homogenate (CPH), used alone or in various combinations, were tested as spawning agents in captive E. striatus broodstock. Fifty hormone-induced strip-spawning trials were attempted using a two-injection sequence in which a priming dose (PD) was followed 24 h later by a resolving dose (RD). Hormone treatment strategies tested included, HCG alone (PD = 1000 IU kg −1 bw, RD = 500 IU kg −1 bw), LHRH-a alone (PD = 50–100 μg kg −1 bw, RD = 100–200 μg kg −1 bw), HCG (500 IU kg −1 bw) in combination with LHRH-a (50–100 μg kg −1 bw) as priming or resolving doses, and CPH (PD = 10 mg kg −1 bw) in combination with LHRH-a (RD = 50–100 μg kg −1 bw). As an alternative to hormone injection, intramuscular implantation of a cholesterol pellet containing LHRH-a (200–250 μg) was tested in two females. Females with mean oocyte diameters ranging from 482 to 561 μm were suitable for hormone-induced spawning. Oocyte diameter increased to 524–708 μm within 24 h of the priming dose and to 852–945 μm within 9–16.4 h following the resolving dose. Average diameter of spawned (water hardened) eggs ranged from 879–978 μm. Although fertilization rate (0–94.7%) varied widely among trials, successful spawnings (fertilization rate ≥ 50%) were obtained in all of the hormone strategies tested. Use of different hormones in combination showed no advantage over a single-hormone strategy. As HCG appeared to cause an immune response, LHRH-a is recommended for repeated application. Implantation of LHRH-a produced variable results, inducing ovulation in one female, but apparently inducing sex reversal in the other.

Hatchery study of the effects of temperature on eggs and yolksac larvae of the Nassau grouper Epinephelus striatus

Abstract The effects of temperature on eggs and yolksac larvae of the Nassau grouper (Epinephelus striatus) were examined under controlled, hatchery conditions. Artificially-fertilized eggs, obtained by induced spawning of captive adults, were stocked (36 eggs per 1) into 15 500 1 cylindroconical indoor tanks at temperatures of 26, 28 and 30 °C, with five tanks per treatment. A salinity of 37 g l−1 and a photoperiod of 12 L: 12 D were maintained. Incubation time to hatching was inversely related to temperature, decreasing from 24.9 h post-fertilization (p.f.) at 26 °C to 20.4 h p.f. at 30 °C, but hatching success (avg. = 82.5%) did not vary with temperature. Survival of pre-feeding larvae declined more rapidly at the higher temperatures to 91.4, 80.7 and 42.2% by Day 1 p.h. at 26, 28 and 30 °C, respectively, indicating that early survival was influenced by factors unrelated to feeding. Development time to the first-feeding stage was inversely related to temperature, decreasing from 86 h p.f. (2.54 d p.h.) at 26 °C to 71 h p.f. (2.11 d p.h.) at 30 °C. Lower temperatures delayed starvation, with survival falling to 32.3, 9.3 and 1.2% by Day 4 p.h. at 26, 28 and 30 °C, respectively. A temperature of 26 °C is deemed advantageous to higher temperatures for incubating eggs and for rearing first-feeding larvae, although even lower temperatures may be feasible. Temperatures within an ecological range can markedly influence development rates of E. striatus eggs and yolksac larvae and hence, dispersal potential, first-feeding and survival in the field.

Light Intensity and Salinity Effects on Eggs and Yolk Sac Larvae of the Summer Flounder

Abstract The effects of light intensity and salinity on eggs and yolk sac larvae of summer flounder Paralichthys dentatus were examined under controlled laboratory conditions. Fertilized eggs (early gastrula stage), obtained by induced spawning of captive broodstock, were stocked (53 eggs/L) into forty-eight 5-L translucent containers under light intensities of 0 (constant dark), 500, 1,000, and 2,000 lx and at salinities of 26, 31, and 36 g/L. Temperature was 19°C and photoperiod was 12 h light:12 h dark. Light intensity and salinity produced significant (P < 0.05) additive effects on larval growth. At the stage when 97% of the yolk sac was absorbed (114–131 h postfertilization, hpf), at the first-feeding stage (129.5–135 hpf), and at yolk exhaustion (153.5–159 hpf), notochord lengths were generally maximal at low light intensity (500 lx) and high salinity (36 g/L) and minimal at high intensity (2,000 lx) and low salinity (26 g/L). Yolk utilization efficiency declined significantly (P < 0.01) with increa...

Temperature Effects on Feed Utilization and Growth of Postsettlement Stage Nassau Grouper

Abstract Feed utilization and growth of hatchery-reared, postsettlement stage Nassau grouper Epinephelus striatus (mean weight = 3.20 g) were compared for 63 d at temperatures of 22, 25, 28, and 31°C under controlled laboratory conditions. Final weights (Wf ) and specific (SGR) and relative (RGR) growth rates were significantly (P < 0.05) higher at 28 and 31°C (Wf = 10.5–12.4 g, SGR = 1.95–2.07%/d, RGR = 246–273%) than at 22 or 25°C (Wf = 7.33–8.70 g, SGR = 1.32–1.52%/d, RGR = 131–164%). Temperature unit requirements per gram of growth (range = 342–234°C × d/g) also appeared to decrease with temperature within this range. Higher growth with increasing temperature was related to feed consumption (% body weight/d), which increased significantly (P < 0.05) from 1.60 at 22°C to 2.23 at 31°C. Feed conversion ratio (weight fed/weight gained: range = 1.23–1.04) and condition factor (103 × weight/length3; range = 30.6–31.7) did not differ among treatments. Survival did not differ and remained high (range = 96.4–1...

Growth and Feed Utilization of Hatchery-Reared Juvenile Nassau Grouper Fed Four Practical Diets

Abstract The effects of four practical diets, formulated for carnivorous marine finfish, on growth, feed utilization, and body composition of hatchery-reared juvenile Nassau grouper Epinephelus striatus (mean weight ± SD = 2.37 ± 0.75 g) were compared for 56 d in 145-L flowthrough seawater (36–38 ‰) aquaria. Diets differed in crude protein (CP) and crude lipid (CL) content as follows: low CP (43.5%), low CL (5.91 %) trout grower (LP–LL); midlevel CP (52.7%), high CL (15.2%) salmon grower (MP–HL); midlevel CP (55.6%), low CL (7.79%) Japanese formulation for carnivorous fish (MP–LL); and a high CP (61.8%), high CL (14.2%) research diet for dolphin (mahimahi) Coryphaena hippurus (HP–HL). Energy : protein ratios (E:P) of these diets were 35.2, 32.0, 28.3 and 28.9 kJ/g, respectively. Relative growth rate (RGR, % increase in weight) and specific growth rate (SGR, % increase in body weight/day) were strongly correlated (P < 0.0005) to dietary CP and E:P ratio and were higher (P < 0.05) for fish fed the MP–LL and...

Hormone-Induced Multiple Spawning of Captive Nassau Grouper Broodstock

Abstract During a 5-month period from 3 December 1991 to 28 April 1992, two female Nassau grouper Epinephelus striatus were spawned three times and one female two times by hormone induction. The interval between spawnings for an individual female ranged from 28–75 d. Successful spawnings (fertilization rate > 50%) were induced in females with average oocyte diameters ranging from 517–544 μm by a primary injection of human chorionic gonadotropin (HCG; 1,000 IU/ kg body weight), followed by a second injection (500 IU!kg body weight) after 24 h. Time of strip-spawning ranged from 37–45 h after the first injection and was inversely related to average water temperature (range, 22.4–26.4°C). Mean diameters spawned eggs were 871–959 μm, and the number of eggs spawned per female ranged from 200,000 to 2,000,000. Fertilization and hatching success were 17.9–80.6% and 68.3–90.1 %, respectively. The results demonstrate a reproductive capacity that minimizes broodstock requirements and enhances suitability of the Nas...

Temperature Effects on Eggs and Yolk Sac Larvae of the Summer Flounder at Different Salinities

Abstract The combined effects of temperature and salinity on eggs and yolk sac larvae of summer flounder Paralichthys dentatus were examined under controlled laboratory conditions. Fertilized eggs (early gastrula stage), obtained by induced spawning of captive broodstock at 17°C and 36 g/L salinity, were stocked (60 eggs/L) into forty-five 5-L translucent containers at temperatures of 16, 20, and 24°C and at salinities of 22, 28, and 34 g/L. Light intensity was 500 lx, and photoperiod was 12 h light: 12 h dark. At 16°C and 20°C, hatching rate was moderate to high (57.8-99.0%) at all salinities; at 24°C, hatching rate was high at 34 g/L (75.2%) but poor at 28 g/L (0%) and 22 g/L (30.5%), indicating a high-temperature-low-salinity inhibition (P < 0.001). At the first feeding stage and at the stage when 97% of the yolk sac was absorbed (YSA), notochord lengths increased (P < 0.05) with decreasing temperature, from a minimum at 24°C to a maximum at 16°C. Yolk utilization efficiency appeared to show a similar ...

Effects of Dietary Lipid Levels and Energy: Protein Ratios on Growth and Feed Utilization of Juvenile Nassau Grouper Fed Isonitrogenous Diets at Two Temperatures

Abstract The growth and feed utilization of juvenile Nassau grouper Epinephelus striatus (mean weight = 2.12 g; N = 9) were compared for 75 d in laboratory aquaria supplied with flow-through seawater. Fish were fed four isonitrogenous (45% crude protein) diets differing in lipid content (6, 9, 12, or 15% dry weight) and energy: protein (E:P) ratio (28.4, 31.0, 33.5, or 36.0 kJ/g protein) at two temperatures (25°C and 30°C). Specific growth rates and final weights increased (P < 0.001) with decreasing dietary lipid and E:P ratios, from a minimum of 1.20% of body weight (bw) per day (5.21 g) for fish fed the 15% lipid diet to a maximum of 2.04% bw/d (9.31 g) for fish fed the 6% lipid diet. The specific growth rate was greater (P < 0.01) at 30°C (1.38–2.09%/d) than at 25°C (1.02–1.99%/d). Feed consumption (2.16–3.30% bw/d) was inversely correlated (P < 0.001) to dietary lipid content and E:P ratio and was greater (P < 0.005) at 30°C than at 25°C. Feed conversion ratio (1.91–2.74) was positively correlated an...