Progress 09/15/04 to 09/14/06
Outputs
Two photothermally-controlled recirculating maturation systems were constructed to permit out-of-season spawning of yellow perch broodstock. Each system consists of a 400-gallon (1,762 l) tank and a filtration system with sand filter and trickling biofilter. Temperature is controlled by means of a 9,500 BTU 3/4-hp chiller to cool the water and a 14,500 BTU heat pump to heat and chill the air. A lighting system controlled by an astronomic timer allows for photoperiod control. Four hundred and fifty 1-year old, fast-growing yellow perch were selected as candidate broodstock from a crop of yellow perch that were raised from fingerling to market size in a recirculating aquaculture system. These fish were reared as future broodstock in an indoor recirculating aquaculture system under conditions of constant illumination and temperature (22 degrees C) from June of 2004 - September of 2005. In June of 2005 chronic mortalities began occurring in this population. Necropsy of
moribund fish revealed massive accumulations of visceral fat (more than 30 percent of BW) and severe lipidosis of the liver. Gonadal development was minimal. Pockets of bacterial development were observed in the visceral fat. Dr. Steven Smith, a veterinarian at Virginia Tech who specializes in fish health, attributed the observed mortalities to liver failure and advised that these fish were unlikely to spawn and were poor candidates for a broodstock. The fish were subsequently destroyed. No replacement broodstock were available so experiments on photothermal control of the yellow perch spawning were not carried out. An economic model of yellow perch production in recirculating systems was developed and populated with data descriptive of producing market-sized yellow perch in a pilot scale facility consisting of two 5,670-gallon (24,978 l) recirculating aquaculture systems. These data represented realistic production parameters for a small-scale production system. Model results
indicate that yellow perch production is not profitable in a small scale system such as that operated at the SW Virginia Aquaculture Research Center, primarily because the management costs were distributed over too few pounds of production. Work with the economic model is ongoing to determine if production of yellow perch in larger scale recirculating aquaculture systems can be profitable, and to determine the sensitivity of the Return on Investment to variables such as growth rates, costs of key operating inputs, and market price. A preliminary study of the use of the fish effluent in horticultural production was conducted to determine the feasibility of using the waste from our systems, which contains salt that is added to maintain fish health. The preliminary study indicated that at the current salt levels, plant production is possible for a wide variety of plants. Insect and disease infestation were found to be potential problems and will be evaluated as the research into
aquaponics continues.
Impacts
The number of producers expressing an interest in recirculating aquaculture has significantly increased during the past year, with 13 new producers interested in installing systems on their farms in southwest Virginia. Before these individuals invest in recirculating production systems for yellow perch they will need reliable information on the profit potential of this type of enterprise. The data collected on yellow perch RAS capital and operating costs, combined with the economic model developed by Virginia Tech researchers, will help producers to evaluate the risks associated with yellow perch production in recirculating aquaculture systems and to decide whether or not to invest in a recirculating aquaculture system. Preliminary results indicate that small-scale yellow perch recirculating aquaculture systems are unlikely to be profitable, and as a result, several producers have decided not to build recirculating aquaculture systems. The information obtained from
aquaponics studies will aid in future direction of work at the Center and provide data useful to producers who are considering use of animal waste for plant production
Publications
- Gonzales, S., G.J. FLick, S.F. O'Keefe, S.E. Duncan. E. McLean, and S.R. Craig. 2006. Composition of Farmed and Wild Yellow Perch. Journal of Food Composition and Analysis. 19(6-7):720-726.
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Progress 10/01/04 to 09/30/05
Outputs
A wet lab was constructed and necessary equipment installed to perform water quality testing and to evaluate live feeds production. The wet lab will also house the algae reactor portion of the live feeds production project. The wet lab was designed with additional safety equipment to protect employees and the yellow perch with improved ventilation to remove harmful gasses from the hatchery addition, improved lighting in comparison to the remainder of the facility, and other personal safety equipment. With the hatchery building construction completed (see Aquaculture Virginia, 2003), the Center was able to secure a donation of valuable hatchery and live-feeds equipment that will be used to complete the project. A growth and feeding model for production of yellow perch has been developed, and data from the current production cycle is being used to validate this model, as well as to enhance the application of this model for aquaculture producers. An economic model has
also been developed for yellow perch production in recirculating aquaculture systems. The feed and growth model is an important production planning tool that will help producers to accurately predict when crops will reach targeted market weights. The model also serves as an important element of the economic planning model. The economic planning model will allow producers to evaluate the profit potential of alternative system designs and production plans. A preliminary study of the use of fish effluent to grow plants was conducted in the greenhouses during fall 2004. Plants studied included cabbage, pansy, chrysanthemum, and a variety of woody landscape ornamentals. This study revealed that the level of salt used for yellow perch production in a recirculating systems did cause some damage to plants. Improved plant growth was shown using effluent mixed with municipal water, which reduced the visible signs of plant stress related to salts. The effluent study also allowed for design of a
system where effluent will be collected from the production systems and held for use in the greenhouses. The collection system will allow collected waste to be either held to allow settling of solids from the waste water or agitated to keep solids in suspension, expanding future research opportunities. The study raised several issues for future research including food safety issues of produce grown in fish effluent, increased pest damage on effluent-produced crops, and the effect of effluent on plant growing media, as it was found that soil texture and structure in effluent studies deteriorated at a more rapid rate than soil from the control (municipal water).
Impacts
The number of producers expressing an interest in recirculating aquaculture has significantly increased during the past year, with 13 new producers interested in installing systems on their farms in southwest Virginia. The information gained from studies conducted will provide valuable data needed by producers to be economically successful and reduced associated risks. The information obtained from aquaponics studies will aid in future direction of work at the Center and provide data useful to producers who are considering use of animal waste for plant production.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
This project is a continuation of VA-428028 and VA-428083. Nine thousand yellow perch (Perca flavescens) are currently being grown in the production systems at the Southwest Virginia Aquacultural Research and Extension Center (SWVA AqREC) in Saltville, Va. The interior of the hatchery has been completed, and construction of three foam fractionaters (one for each recirculating aquaculture system) has begun. The fractionators will reduce the solids load, thereby increasing oxygen levels, reducing heterotrophic bacterial growth, and improving fish health.
Impacts
Year-round production of yellow perch will increase the profits and reduce the cost of producing fish for fish farmers. Aquaponics, which combines the culture of fish and plants in the same system and uses nutrients derived directly from recirculated water in an aquaculture system to cultivate plants, has the potential to augment income for the producer.
Publications
- No publications reported this period
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