C. R. Arnold

Rapid 13C/12C turnover during growth of brown shrimp (Penaeus aztecus)

SummaryUsing natural-abundance 13C/12C ratios as tracers, carbon turnover rates were determined for postlarval brown shrimp, Penaeus aztecus, in five laboratory growth experiments. Although tissue turnover in adult animals generally occurs during maintenance metabolism and is a function of time, turnover for young postlarval shrimp was accelerated during growth, and was primarily a function of weight gained rather than time. Metabolic loss of tissue carbon during growth was usually approximated by the function, Fraction lost=1-(initial weight/final weight). For shrimp that switch diets in the sea, model calculations show that this high turnover rate coupled with a four-fold weight increase suffices for shrimp to achieve a close isotopic resemblance of 1‰ or less (δ13C units) to the new diet.In accordance with these predictive calculations, shrimp which had increased in weight by a factor of four or more in the culture experiments showed essentially constant isotopic values reflecting their new diets. For these larger animals, the average animal-diet difference varied across three diets from-0.9 to +11‰, and the δ13C range among individuals was ≦1.4‰ in each experiment.

Replacement of fish meal in practical diets for the Pacific white shrimp, Litopenaeus vannamei.

Abstract The use of a co-extruded soybean poultry by-product meal (CEPM) and flashed dried poultry by-product meal (FD-PBM) was evaluated as replacements for fish meal in a practical diet formulated to contain 32% crude protein and 8% lipid. Each meal was substituted for menhaden fish meal on an iso-nitrogenous basis and offered to juvenile Litopenaeus vannamei (mean initial wt.±S.D., 0.37±0.015 g) over a 6-week period. Inclusion levels ranged from 0 (30 g fish meal /100 g diet) to 80% replacement (6 g fish meal/100 g diet). Replacement of fish meal with CEPM resulted in equivalent values for final weight, percent weight gain and feed efficiency (FE) and a significant increase in protein conversion efficiency (PCE). Similarly, replacement of 40%, 60%, and 80% of the fish-meal protein in the basal diet with FD-PBM resulted in a significant increase in weight gain and FE. Although not significant, there was also a general increase in PCE when FD-PBM was included in the diet. Under the reported conditions, survival, FE, and PCE values were either improved or were not significantly influenced by the replacement of menhaden fish meal with either CEPM or FD-PBM. Hence, these products can be used to reduce the fish-meal content of practical diets from 30 to 6 g/100 g dry wt.

Plasma cortisol and secondary stress responses of cultured red drum (Sciaenops ocellatus) to several transportation procedures

Abstract Transportation procedures induced rapid elevations in plasma cortisol and glucose concentrations (100–160 ng/ml and 60–140 mg/100 ml, respectively) within 15–30 min of capture and loading in cultured juvenile red drum. The elevations were transient and plasma levels of cortisol returned to baseline levels during the 5.5 h transport, suggesting that capture and loading are the most traumatic procedures. Plasma glucose concentrations had returned to baseline values within 1–2 days of transport. Plasma osmolality increased during transportation in 32 ppt seawater and decreased during transport in 4 ppt seawater. Survival ranged from 96 to 100%, indicating that despite the trauma associated with initial transport procedures, juvenile red drum can be transported successfully in seawater or low salinity seawater. Anesthesia with MS-222 (80 mg/l) prior to capture, coupled with the use of sedating doses (5 and 25 mg/l MS-222) in the transport tanks, did not decrease the magnitude of the stress responses. On the contrary, the corticosteroid stress response was augmented in fish transported in 25 mg/l MS-222. Laboratory tests showed that long-term (30–90 min) exposure to sedating doses of the anesthetic caused a dose-dependent increase in plasma cortisol levels, whereas anesthetization of red drum with MS-222 prior to capture and transport in anesthetic-free seawater markedly reduced the plasma corticosteroid response after capture/loading and at the end of transport. Plasma glucose levels and osmolality were also lower in those fish anesthetized prior to capture. These results suggest that acute exposure to immobilizing doses of an anesthetic, MS-222, is an effective method of reducing endocrine and metabolic disturbances during transportation of red drum.

Plasma Cortisol and Secondary Stress Responses of Red Drum to Handling, Transport, Rearing Density, and a Disease Outbreak

Abstract The effects of some common fish culture procedures on the biochemical stress responses of juvenile red drum (Sciaenops ocellatus) were examined in the present study. Plasma cortisol, glucose, and osmolality were measured in cultured red drum subjected to capture and handling, transportation, an outbreak of disease, and different rearing densities. Capture and handling elicited rapid, marked elevations of plasma cortisol and glucose in the fish. The responses were transient, however, and the plasma concentrations returned to initial values 1 d after handling. Similarly, transportation of red drum induced rapid but transient plasma cortisol, glucose, and osmolality responses and caused no mortality. An outbreak of disease evoked cortisol, glucose, and osmolality stress responses in red drum. As the disease progressed, the plasma cortisol and osmolality responses became more pronounced. Fish reared at different densities had similar plasma glucose levels. Cortisol titers were temporarily elevated in...

Co-feeding microparticulate diets with algae: toward eliminating the need of zooplankton at first feeding in larval red drum (Sciaenops ocellatus)

The effect of adding algae to the culture water used to rear red drum larvae was evaluated in terms of growth, survival and digestive enzyme activity. Red drum larvae were subjected to one of the following dietary regimes from first feeding (day 3 post-hatch) to day 14: (1) zooplankton supplemented with algae (L-A), (2) zooplankton without algae (L-NA), (3) a microparticulate diet with algae (M-A) and (4) the microparticulate diet alone (M-NA). The presence of algae in the rearing tanks improved growth of red drum larvae for both types of feeds. Growth was significantly higher (P<0.05) in larvae reared in the presence of algae (L-A and M-A) than in larvae raised in the corresponding treatments without algae (L-NA and M-NA). Red drum larvae raised on the microparticulate diet and algae (M-A) grew as well as the zooplankton treatment with no algae (L-NA), and were not significantly different from the L-A treatment. The larvae fed the microparticulate diet in the absence of algae (M-NA) were significantly smaller than the other three treatments. These results were consistent for two separate feeding trials. Final survival was highly variable in all treatments; nevertheless, mean final survival values were 30% higher in treatment L-A compared to L-NA (14.1 and 10.1%, respectively) and 42% higher in M-A than for M-NA (6.2 and 4.0%, respectively). Significantly higher trypsin and aminopeptidase activity was observed in the presence of algae, which may have influenced the digestion of the diet. Our results demonstrate that red drum larvae may be raised on a microparticulate diet from first feeding without the use of zooplankton.

Partial Replacement of Fish Meal with Meat-and-Bone Meal, Flash-Dried Poultry By-Product Meal, and Enzyme-Digested Poultry By-Product Meal in Practical Diets for Juvenile Red Drum

Abstract To reduce long-term dependence upon fishery resources, we evaluated selected terrestrial by-products as alternatives to fish meal for rearing juvenile (mean weight, 2.3 ± 0.1 g) red drum Sciaenops ocellatus. Over a 6-week feeding trial, 10 test diets (basal diet and 9 test diets) were formulated on an isonitrogenous (44% gross protein) basis. The primary protein sources in the basal diet were fish meal and soybean meal, which were incorporated at 30 and 24.8 g/100 g of diet, respectively. Replacement of fish meal in the test diets ranged from 16.6% to 66.7%. Low ash meat-and-bone meal (MBM), flash-dried poultry by-product meal (PBM), and enzyme-digested poultry by-product meal (EPM) were used to replace the fish meal. All four MBM diets produced significantly lower weight gain compared with fish maintained on the basal diet. Feed efficiency (FE) and protein conversion efficiency (PCE) were similar for the 16.6% MBM diet and the basal diet, but higher levels of MBM produced significantly lower FE ...

The effects of dietary protein level on growth, feed efficiency and survival of juvenile Florida pompano (Trachinotus carolinus)

Florida pompano is considered a suitable candidate for mariculture due to its ready adaptation to culture systems, acceptance of formulated feeds, and rapid growth rates. Little information on the nutritional requirements or growth rates under controlled conditions have been reported. A seven week feeding experiment was conducted with juvenile fish (mean wt. 4.5 g) to evaluate the effect of dietary protein level on growth, feed intake, feed utilization and survival. Four practical diets were formulated to be isoenergetic and to contain increasing levels of protein (30, 35, 40 or 45% crude protein). Although total feed intake was not significantly different among treatments, feed intake expressed as amount consumed per unit of body weight was significantly different among treatments. Fish fed the highest protein diet had lower percentage daily feed consumption values than did fish fed the lowest protein diet. Growth and feed efficiency ratios increased with dietary protein level and were highest for fish fed the diet containing 45% protein. The results obtained in the present study indicate that juvenile Florida pompano required a minimum of 45% protein for maximum growth and feed efficiency ratio when fish meal and soybean meal are the primary sources of protein.

Cryopreservation of Atlantic croaker spermatozoa

An artificial insemination method was standardized. The effects of various extenders, dilution ratios, cryoprotectants, equilibration times, freezing and thawing rates, and semen and egg quantities on fertilization capacity of post-thaw Atlantic croaker Micropogonias undulatus spermatozoa were examined to optimize cryopreservation procedures. Fertilization rates using NaCl, Glucose, and sucrose solutions were comparable to those achieved with more complex extenders. No fertilization was obtained when methanol was the cryoprotectant. The optimum ratio of semen to DMSO to extender was 10%: 15%: 75%. No significant difference (P<0.05) in fertilization rates was found among freezing rates ranging from −10°C/min to −150°C/min. The two-step freezing method gave a fertilization rate similar to that obtained with the conventional one-step freezing method.

Evaluation of growout diets with varying protein and energy levels for red drum (Sciaenops ocellatus)

The augmentation of nutrient retention and subsequent reduction of effluent waste generated by aquaculture production facilities are important factors in lowering production costs while simultaneously minimizing pollution and environmental impact resulting from intensive growout culture. Consequently, the present study was designed to evaluate the influence of dietary protein and energy levels on growth and nutrient utilization of the red drum in the initial stages of growout culture. Four practical diets were formulated to contain 44, 40, 36, and 32% protein with practical energy:protein (E:P) ratios. Additionally, the E:P ratio of the 44% protein diet was increased and the E:P ratio of the 32% protein diet was reduced. Each diet was fed to juvenile red drum (mean initial weight 50 g) to apparent satiation in triplicate tanks containing 670 l of seawater at 35‰, 28.8±1.4°C for 13 weeks. Significant differences (P<0.05) in final weights, protein consumption, feed efficiency (FE), protein conversion efficiency (PCE) and intraperitoneal fat ratios (IPFR) were observed due to the dietary treatments. Weight gain and FE generally increased with protein and energy content of the diet. Increasing the lipid content of the 44% protein diet resulted in significantly higher FE values but also doubled the amount of fat deposited in the peritoneal cavity. Reduction of digestible energy from 335 to 279 kcal/100 g diet in the 32% protein diet did not significantly influence body composition or feed consumption. Based on regression analyses of feed consumption data, consumption rates appear to be primarily influenced by the weight of the fish and not the energy content of the diet. Consequently, reduced growth rates of fish offered the low protein feeds appear to be due to reduced protein intake and not imbalances in E:P ratios. These data indicate that red drum reared in seawater require at least 44% dietary protein (dry weight basis) for maximum growth and FE.

The design, management and production of a recirculating raceway system for the production of marine shrimp

Despite continuing problems with disease outbreaks and environmental concerns over effluent pollution and land usage, world shrimp farming continues to expand. Although traditional pond production systems will continue to be the dominant driving force in aquaculture expansion, there is continued interest in alternate production systems. The use of high density, water reuse systems is one alternative to conventional pond production systems which addresses restrictions associated with environmental regulations and user conflicts of coastal land and water usage. This paper reports on techniques which have been developed for the production of marine shrimp in recirculating raceway systems and typical results which have been observed over a 6-year production period. Both bait shrimp (Penaeus setiferus) and food shrimp (P. vannamei) have been produced with final biomass loads as high as 10 kg/m3 utilizing 100–120-day and 160–175-day production cycles, respectively. Results from multi-phase growout are most promising and indicate that this may be a suitable mechanism to optimize biomass loading of the culture system. Although the economic viability of recirculating production systems for bait and food size shrimp have yet to be proven, the consistent results of production, low water usage and ease of waste management are encouraging and warrant further economic and marketing evaluations.