Journals, Virginia Tech Publishing

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Availability of Dietary Zinc Sources and Effects on Performance of Pacific White Shrimp Litopenaeus vannamei(Boone)
Bharadwaj, Anant S.; Patnaik, Susmita; Browdy, Craig L.; Lawrence, Addison L. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2012-06-01)
A study was conducted to evaluate the response of Pacific white shrimp Litopenaeus vannamei to inorganic or chelated sources of dietary zinc. Two sets of diets, one supplemented with zinc from zinc sulfate (55, 80, 116, 168, 243 and 363 ppm zinc) and the other with zinc from a chelated source (methionine hydroxy analog chelate; 39, 52, 65, 78 and 104 ppm zinc) were fed to replicate groups of juvenile shrimp (N = 8; 0.4 g initial weight) for 6 wk. All experimental diets contained 1.38% phytic acid reflecting levels in typical commercial feeds. Final weight, growth rate and biomass of shrimp fed zinc sulfate supplemented diets (243 and 363 ppm total zinc) were significantly higher (p < 0.05) than that in shrimp fed the base diet. In contrast, performance of shrimp fed the chelated source of zinc was significantly higher than shrimp in the control group at much lower levels of supplementation (65 and 78 ppm total zinc). Results indicate that shrimp required 3-4 times more dietary zinc from zinc sulfate than zinc from a chelated source to promote comparable growth when fed diets containing phytic acid. The chelate tested proved to be a safe, effective and available source of zinc for the Pacific white shrimp.
Book Review - Anaesthetic and Sedative Techniques for Aquatic Animals, Third Edition
Smith, Stephen A. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2009-06-01)
Book Review - Species and System Selection for Sustainable Aquaculture
Schwarz, Michael H. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2010-06-01)
Book Review: Aquaculture and Fisheries Biotechnology: Genetic Approaches
Hallerman, Eric M. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2005-06-01)
Book Review: Aquaculture Biosecurity: Prevention, Control, and Eradication of Aquatic Animal Disease
Smith, Stephen A. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2008-06-01)
Book Review: Finfish and Shellfish Bacteriology Manual: Techniques and Procedures
Cipriano, Rocco C. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2004-06-01)
Book Review: Fish Nutrition (Third Edition)
Goddard, S.; Halver, J. E.; Hardy, R. W. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2003-06-01)
Book Review: Food Intake in Fish
Craig, Steven R. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2001-06-01)
As the field of fish nutrition continues to grow and flourish, current reference texts updated with the latest and most relevant references are becoming more important and necessary. Food Intake in Fish, edited by Dominic Houlihan, Thierry Boujard and Malcolm Jobling is an excellent addition to the library of anyone involved in the culture of, or experimentation with fish...
Book Review: Practical Genetics for Aquaculture
Lutz, C. G. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2002-06-01)
Book Review: Public, Animal, and Environmental Aquaculture Health Issues
Ronsholdt, B. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2003-06-01)
Book Review: Recirculating Aquaculture, 2nd Ed. by M.B. Timmons and J.M. Ebeling
Hall, Steven G. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2011-06-01)
Characteristics of the Recirculation Sector of Finfish Aquaculture in the United States and Canada
Delabbio, Juliette L.; Murphy, Brian R.; Johnson, G. R.; Hallerman, Eric M. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2003-06-01)
In the autumn of 2001, a survey was conducted to examine basic farm production and human resource characteristics of recirculation facilities in the United States and Canada currently growing finfish. An 86% response rate was achieved. The survey data indicate that this sector of aquaculture is quite heterogeneous. The number and pounds of fish produced is quite variable, with presence of small-, medium- and large sized farms in this sector. Recirculation technologies are employed to culture a wide variety of both warmwater and coldwater fishes in both saltwater and freshwater situations. The four fishes most commonly grown in recirculation units in the United States and Canada are Atlantic salmon smolts, tilapia, hybrid striped bass and ornamental fishes. A high proportion of facilities using recirculation technologies use pumped groundwater as a primary water source. Over 40% of facilities represented in the survey rely on a single water source to sustain their operation and have no secondary water source as backup. Management personnel of recirculation facilities are highly educated; more than 74% of respondents reported holding at least an undergraduate degree. The majority of personnel managing recirculation facilities are middle-aged individuals who have over 10 years of related work experience. The findings of this study represent the first empirical description of the recirculation sector of finfish aquaculture in the United States and Canada.
Comparison of Growth, Feed Conversion and Survival of Morone saxatilis female x M. mississippiensis male and M. saxatilis female x M. chrysops male Hybrids Reared in Recirculating Aquaculture Systems
Bosworth, B. G.; Libey, George S.; Wolters, W. R. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2001-06-01)
Striped bass female (M. saxatilis) x white bass male (M. mississippiensis), (SBxWB, n = 300) and striped bass female x yellow bass male (M. chrysops) (SBxYB, n = 300) fingerlings, initial mean weight 91 g and 62 g, respectively, were reared in recirculating aquaculture systems at densities of 118 fish/m3 for 120 days. Mean weight increased 309 g and 151 gin SBxWB and SBxYB, respectively. ,final mean weight and total length, and rate of weight and length increase were higher for SBxWB than SBxYB. Condition factor and survival were higher for SBxYB (1.04 and 99.3%, respectively) than for SBxWB (1.01 and 96.0%,respectively). Mean feed conversion ratio (FCR) was lower for SBxWB (1.4) than for SBxYB (1.6). Significant time x hybrid interactions indicated that growth rate of SBxYB improved, relative to SBxWB, as the study progressed. Positive linear trends for total ammonia, unionized ammonia, and nitrite indicate water quality deteriorated as the study progressed. Time x hybrid interactions for growth rate may have been due to differential responses of SBxYB and SBxWB to deterioration of water quality. Although SBxYB had slightly better survival than SBxWB and their growth rate improved relative to that of SBxWB, the slow overall growth of SBxYB limits its potential for recirculating system production.
Comparisons of Tilapia Seed Production Under Various Broodstock Densities and Fry Stocking Densities
Glenney, G. W.; Libey, George S. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2002-06-01)
Three types of seed (eggs, sac-fry, and fry) production for Rocky Mountain White® hybrid tilapia, (O. niloticus x O. aureus), were compared under green water conditions over a six-month period in an environmentally-controlled greenhouse at the Virginia Tech Aquaculture Center. Rectangular tanks were stocked with broodstock (mean wt. 680 g), at a sex ratio of 3 females to 1 male. Nine tanks were stocked at one of three densities (1, 2, and 4 females/m2), and seed was collected from the females' mouths weekly. Three additional tanks were stocked at a density of 2 females/m2, and fry were collected from the edges of the tanks daily. Average number of viable fry produced by the clutch removal method at 1 female/m2 was significantly higher than the combined average production of densities at 2 and 4 females/m2 (p< 0.02). Even though there was no significant difference between viable fry production per meter sq. (p>0.05), the highest density consistently produced more fry/m2. No significant difference was observed in viable fry production between the clutch removal method and the natural mouth-brooding method (p>0.05). The mean monthly hatchery seed survival was 65.7 ± 2.3%, which varied largely depending on initial seed developmental stage. The effects of stocking density on growth and survival were evaluated by stocking 14-16 day old artificially incubated fry (25.5 ± 0.32 mg, 12.1 ± 0.04 mm), into 150-liter troughs at three densities (3, 6, and 12 fry/ liter) under green water conditions for 30 days. Significant differences were observed between mean weight, length, survival, and feed conversion ratios among the various fry stocking densities (p<0.05).The greatest growth was at a density of 3 fry/liter, while survival was not affected until a density of 12 fry/liter was reached. These results suggest that to maximize fry production and reduce labor, a density of 4 females/m2 or higher be used under the natural mouth-brooding seed collection method. They also suggest a fry stocking density between 6 to 12 fry/liter should be used with periodic grading or sex reversal to reduce cannibalism and increase growth.
Design and Performance of an Indigenous Water Recirculating Aquaculture System for Intensive Production of Nile Tilapia, Oreochromis niloticus (L.), in Saudi Arabia
Al-Hafedh, Y. S.; Alam, A. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2007-06-01)
The increasing demand for fish, and the scarcity of fresh water in Saudi Arabia both press the need to adapt new technologies for intensive water recirculating aquaculture to maximize water recycling and increase fish production. Using locally available materials, a commercial-scale recirculating aquaculture system was developed in triplicate to produce Nile tilapia. The system was operated to produce more than 50 kg fish/m3/cycle, and the filters were evaluated for their efficiency in removing organic wastes from the effluent. Each replicate consisted of a culture tank, two mechanical filters with sand/gravel medium, two submerged biofilters with plastic media, a sump and two pumps. Mixed sex tilapia with an average size of 76.4 g were stocked at a density of 188 fish/m3 and fed a 34% protein diet at 3% body weight per day (initially). Water temperature was maintained at 28 ± 1°C, water flow rate was adjusted to 300 liters/min and the culture tank and biofilter were aerated. Water samples were collected from the inlet and outlet of each component and were analyzed for important parameters. Values (± SE) of total ammonia nitrogen (TAN) (0.98 ± 0.1 ppm) and nitrite-nitrogen (NO2-N) (0.48 ± 0.02 ppm) in the fish culture tanks were within the acceptable limits, while the other water quality parameters were also maintained under normal range by the filtration system. Removal rates (± SE) of 186.7 ± 31.59 g TAN/m3/day and 66.53 ± 16.9 g NO2-N/m3/day, respectively, as well as TAN and NO2-N removal efficiencies (31.45 ± 2.32% and 21.05 ± 3.8%, respectively) were measured across the PVC biofilter medium. The area specific TAN and NO2-N removal rates (± SE) or nitrification rates (0.34 ± 0.06 g/m2/day and 0.15 ± 0.05 g/m2/day) for the biofilter were comparable with the performance of other commercial intensive recirculation systems. Mean final weight (±SE), final biomass, growth rate, SGR, FCR, and percent survival for the mixed-sex tilapia were 277.21 (1.76) g/fish, 50.21 kg/m3, 1.34 g/fish/day, 0.86%, 1.89, and 96.53%, respectively, whereas the average water use was 0.4 m3/kg of fish production. Locally available materials were found to be appropriate for solid and organic waste removal. More than 85% of the system water volume could be recycled daily, while fish production per unit space was also multiplied 3-6 fold compared to the traditional culture practice.
Economic Analysis of an Aquaponic System for the Integrated Production of Rainbow Trout and Plants
Adler, P. R.; Harper, J. K.; Takeda, F.; Summerfelt, S. T. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2000-06-01)
Conventional treatment alternatives for phosphorus in wastewater, whether they employ chemical precipitation, physical removal, or land application technologies, represent a significant additional cost to the owner of an aquaculture operation. Plant-based removal of nutrients has the potential to generate additional revenues, which can offset treatment costs. The objective of this analysis was to describe the economic relationship between a 22,680 kg per year recirculating rainbow trout (Oncorhynchus mykiss Walbaum) production system and a hydroponic treatment unit, growing 'Ostinata' lettuce (Lactuca sativa L.) and sweet basil (Ocimum basilicum L.), capable of reducing phosphorus concentration levels in the fish farm effluent to less than 0.1 mg/L. The integration of the fish and plant production system (aquaponics) produces economic cost savings over either system alone. Shared cost savings come from spreading out operating costs (e.g., management, water, nutrients, and overhead charges) and capital costs (e.g., backup generator, used truck, and office equipment) over the two systems. The investment analysis demonstrates the profitability of this combined system over its 20-year expected life. Net present values are positive for a wide range of discount'rates. Internal rate of return analysis shows that for a total investment of $244,720 this system can potentially provide a return of 12.5%. The hydroponic system drives the potential profitability of the combined system with 67% of annual returns derived from plant production.
Effect of a Parabolic Screen Filter on Water Quality and Production of Nile Tilapia (Oreochromis niloticus) and Water Spinach (Ipomoea aquatica) in a Recirculating Raft Aquaponic System
Danaher, Jason J.; Shultz, Charlie R.; Rakocy, James E.; Bailey, Donald S.; Knight, Lasiba (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2011-06-01)
Aquaponics is an integrated fish and plant recirculating production system. Solid fish waste must be removed from the production system to maintain optimal water quality parameters for fish and plant health. The University of the Virgin Islands (UVI) raft aquaponic system’s primary treatment device for solids removal is a cylindro-conical clarifier; however, alternative mechanical filtration devices such as a parabolic screen filter (PSF) may offer advantages. The objectives of the elevenweek experiment were to compare water quality parameters, Nile tilapia (Oreochromis niloticus) production and water spinach (Ipomoea aquatica) production in a raft aquaponic system using either a cylindroconical clarifier or parabolic screen filter for primary treatment of solids in the waste stream. The water quality results showed no significant differences (P > 0.05) between treatments for temperature, oxygen, pH, alkalinity, EC, TAN, NO2-N and NO3-N, macronutrients and micronutrients concentrations, with the exception of copper and zinc. There was no significant difference (P > 0.05) between treatments for the total suspended solids (TSS) concentration entering either primary filtration device; however, there was a significant difference (P ≤ 0.05) between treatments for TSS concentrations exiting the primary filtration device. The PSF treatment had a significantly higher (P ≤ 0.05) TSS concentration exiting the unit and a significantly higher (P ≤ 0.05) TSS concentration in the secondary treatment device (net tank) compared to the clarifier. There were no significant differences (P > 0.05) between treatments for Nile tilapia production, average weight, survival, or feed conversion ratio. There were no significant differences (P > 0.05) in water spinach production or plant tissue analysis between treatments. In conclusion, the PSF used in this experiment performed less effectively in removing TSS compared to the clarifier, would require more labor to clean and would not be recommended for use in a larger raft aquaponic system. In addition, water spinach assimilated dissolved fish wastes well and grew vigorously in the raft aquaponic system.
The Effect of Disinfection Strategies on Transmission of Aeromonas salmonicida and Yersinia ruckeri in a Recirculating Aquaculture System
Bullock, G. L.; Schill, W. B. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2006-06-01)
Continuous addition of Aeromonas salmonicida (which causes furunculosis) or Yersinia ruckeri (which causes enteric redmouth disease, or ERM) broth cultures to recirculating aquaculture systems, without fish, resulted in the presence of these pathogens in the fluidized sand biofilters. Disinfection of the recirculating systems, except biofilters, with 200 ppm sodium hypochlorite and flushing biofilters for 24 hours with spring water did not prevent outbreaks of furunculosis or enteric redmouth disease after stocking Arctic char (Salvelinus alpinus) or rainbow trout (Oncorhynchus mykiss), respectively. Disinfection of the entire recirculating systems with 10 ppm Chloramine-T following outbreaks of furunculosis or ERM, or after addition of broth cultures prevented transmission of enteric redmouth in three trials and in two of three trials with furunculosis. Within 75 days of stocking Atlantic salmon (Salmo salar) with subclinical furunculosis in the recirculating system with rainbow trout, A. salmonicida could be cultured from the mucus of rainbow trout and from the fluidized sand biofilters. Removal of salmon and trout and disinfection of the recirculating system with 10 ppm Chloramine-T prevented a furunculosis outbreak when Arctic char were stocked into the system. However, if the recirculating system was only drained and refilled after removal of salmon and trout, furunculosis occurred within seven days of stocking char.
Effect of Phytase on Growth and Phosphorus Utilization in Japanese Flounder (Paralichthys olivaceus)
Sarker, P.K.; Hosokawa, H. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2009-06-01)
An experiment was conducted to investigate the effect of phytase supplementation on weight gain, phosphorus and protein digestibility and retention in Japanese flounder (Paralichthys olivaceus) fed a soybean meal (SBM)-containing diet. Six levels of phytase-supplemented diets containing 0, 150, 300, 450, 900 and 1500 FTU (phytase unit)/100g diet were assigned to triplicate tanks and fed to Japanese flounder (20 fish/tank, initial average weight 151.4 g) for 40 days. The increase of soluble phosphorus and decrease of phytic acid remained relatively constant for all levels receiving the 300 FTU diet and greater. Significantly (P<0.05) greater weight gain and higher feed conversion ratios (FCR) were observed in fish fed diets supplemented at 300 FTU or greater compared to the control (0 FTU) diet. Significantly (P<0.05) improved apparent protein and phosphorus digestibility, as well as serum calcium concentration were found in fish fed the 300 FTU diet. All diets supplemented at 300 FTU or greater also showed a significantly (P<0.05) improved concentration of bone calcium and zinc. The 150 FTU inclusion level showed only better protein and phosphorus retention, bone phosphorus and magnesium than the control (0 FTU) diet. Therefore, this study indicated that supplementation of phytase is effective and that the 300 FTU/100g SBM-containing diet resulted in the maximum release of soluble phosphorus, and as a consequence improved weight gain, FCR, bone minerals, phosphorus and protein digestibility and retention in Japanese flounder.
The Effect of Solids Removal on Water Quality, Growth and Survival of Litopenaeus vannamei in a Biofloc Technology Culture System
Gaona, C. A. P.; Poersch, L. H.; Krummenauer, D.; Foes, G. K.; Wasielesky, W. J. (Commercial Fish and Shellfish Technologies Program, Virginia Tech, 2011-06-01)
Biofloc technology culture systems can increase the productivity of shrimp culture. Through the use of minimal or zero exchange, biofloc technology culture systems can also reduce the use of water. Diet enhancement through the addition of feed increases the amount of excreta. Together with unconsumed feed, the additional excreta increases the amount of suspended solids and reduces the concentration of dissolved oxygen. In addition, the excess of suspended solids can harm the culture by reducing light penetration. In turn, the lower light levels reduce the abundance of photosynthetic organisms (microalgae) that are also important for water quality and shrimp nutrition. The objective of this study was to evaluate the removal of suspended solids from the water of the culture system by a clarification process (i.e. particle settling). Two treatments were applied: with clarification and no clarification. Six tanks, each 35 m³, were used in the study. In the clarification treatment, 35 m³ of water with bioflocs was pumped from the experimental unit for 6 hours. The water passed through a settling tank (1,000 L) and was returned to the culture unit through gravity. The clarification treatment reduced total suspended solids (24.5%), turbidity (27%) and chlorophyll a (27.8%). The availability of dissolved oxygen and pH values were also greater in the clarification treatment. Growth, feed conversion ratio, survival and productivity were significantly higher (p<0.05) with the removal of suspended solids. Control of the concentration of suspended solids contributed to the improvement of water quality and the growth performance of the shrimp L. vannamei in the superintensive biofloc technology culture.