2009 Annual Report
1a.Objectives (from AD-416)
1. Develop and evaluate solutions that improve efficiencies of scale and reduce water quality constraints for sustainable production. Sub-objectives are to overcome obstacles associated with managing hydraulics and harvests within large (600 m3) tanks, and control of noise, dissolved organic compounds, micro-organisms, and dissolved carbon dioxide.
2. Develop and evaluate sustainable waste management technologies that result in environmentally compatible CIAS. Sub-objectives include work on treatment processes for solids, nutrient removal from aquaculture effluents and mitigation of the impact of feed on water quality.
3. Field test selected rainbow trout germplasm resources for performance in intensive recirculating aquaculture systems.
1b.Approach (from AD-416)
1. The minimum bottom-center drain surface loading rate and the water inlet structure design required to produce rapid solids flushing and safe fish swimming speeds will be identified using a 600 m3 experimental tank. Studies using oxygen and ph feedback control sytems will determine whether carbon dioxide gradients will induce fish to swim out of the culture tank during a harvest event. Sound levels and frequency ranges typically produced in the CIAS environment will be identified and analyzed to determine sound levels and frequencies that can cause hearing loss, damage fish ears and result in reduced growth rates. Controlled ozone and UV systems will be used to determine the combined ozone and UV irradiation dosages required to inactivate total heterotrophic bacteria and total coliform bacteria within a CIAS. Variable feeding rates per make-up water flow rates, fish health indicators and chemical analyses of organic carbon constituent will be used to determine whether advanced oxidation techniques can reduce accumulations of organic carbon constituents that impair fish health. Carbon dioxide removal across forced-ventilated cascade columns in a marine system will be characterized and modeled as a function of air: water loading, packing height, and salinity. Molecular techniques will be used to investigate reservoirs of infection for an emerging chlamydia-like bacterium that causes respiratory disease in Artic char.
2. The solids and nutrients capture and dewatering efficiency of a new bag filter system used to treat microscreen backwash will be determined. Biological nutrient removal will be evalutated within a commercial membrane biological reactor system using seperate stages for aerobic nitrification and anoxic denitrification. In conrolled, replicated feeding studies, the 'low fish meal and high grain proportion' feeds developed by ARS nutritionists at SGPGRU will be evaluated to determine differences in the amount of solid and nutrient waste excreted in comparison with standard fish meal and fish oil based diets, and determine if these grain-based feeds impact water quality in CIAS.
3. Growth and survival data on selected rainbow trout germplasm cohorts or families provided by NCCCWA will be collected. Replicated and commercial scale intensive recirculating aquaculture systems will be operated as performance trial platforms for the evaluation of singular and mixed stocks of trout. Aquaculture systems will simulate conditions found in commercial production environments or will be modified to create enhanced challenges. Trout will be tagged to allow either individual, family or cohort identification as appropriate. Linkage with specific research objectives at the NCCCWA will be maintained.
This report documents research conducted under a Grant Agreement between ARS and THE CONSERVATION FUND. Additional details for the research can be found in the report for the sibling project 1930-32000-003-01G, DEVELOPMENT OF SUSTAINABLE LAND-BASED AQUACULTURE SYSTEMS. The overall goal of this project has been to develop and improve technologies that enhance the sustainability and reduce the environmental impacts of the modern fish farming industry.
Developed Efficient and Cost-Saving Recirculating Aquaculture Systems: Recirculating aquaculture systems reduce water use and place waterborne wastes into concentrated and relatively small discharges that must be either treated before discharge or before reclamation of the heat, salt, and alkalinity found in the water. Treatment of a high strength aquaculture wastewater was evaluated using a pilot-plant membrane biological reactor to determine overall treatment performance, but especially the removal of nutrients and metals. The treatment process removed more than 99.9% of the solids and biochemical oxygen demand, as well as most of the heavy metals and more than 99.8% of the total phosphorus and 97% of the total nitrogen, while recovering 93% of the wastewater discharge. This research identifies better waste management technologies and practices that can be implemented to improve reclamation of water, heat, salts, and alkalinity, while improving waste capture, dewatering, and disposal at aquaculture facilities.
A New Biological and Physical Process Treats High-Strength Aquaculture Wastewater: Recirculating aquaculture systems reduce water use and place waterborne wastes into concentrated and relatively small discharges that must be treated before discharge. Treatment of a high strength aquaculture wastewater using replicated aerated geotextile filter systems that each combine biological nutrient removal, sludge stabilization, and solids thickening was evaluated. The treatment process removed more than 96.9% of the solids and 94.6% biochemical oxygen demand, as well more than 86.9% of the total phosphorus and more than 70% of the total nitrogen. This research will provide engineering criteria and performance expectations that can be used by fish farmers to minimize water resource use and reduce the risk of potentially adverse interactions between aquaculture operations and the surrounding aquatic environment.
Use of zero fish-meal feeds during entire rainbow trout growout cycle: Incorporating grain- or soy-based proteins into commercial fish feeds will reduce fishing pressure on wild populations exploited for their use in fish-meal-based feeds; however, piloting experimental diets with rainbow trout through a growout cycle needed to be carried out to assess fish performance and welfare relative to these outcomes in fish fed traditional diets. The performance and welfare of rainbow trout fed either grain- or fish-meal-based diets, and raised at two different densities, from first feeding up to market size were compared. Density did not appear to significantly affect the outcomes measured; however, by study’s end fish fed the fish-meal-based diet were significantly larger and had better feed conversion, although fin erosion and mortality were significantly higher in this cohort relative to the grain-based diet group. These findings will guide nutritionists in refining the formulations of grain-based feeds in order to increase performance and render these feeds more viable commercially. The demonstration of the usage of grain-based feeds at The Freshwater Institute has already encouraged the adoption of such novel diets at a commercial salmonid operation in West Virginia.
New Technology Improves Fish Harvest: Improvements in fish transfer and grading technologies for large circular tanks must be achieved to better realize their labor-saving potential and provide the technology required to achieve dramatic increases in domestic commercial fish production. We demonstrated that a sidewall drain box commonly used in large dual-drain culture tanks can be modified to harvest fish when used in combination with a crowding device. The new technology provides a highly efficient, inexpensive, convenient, safe, humane, and reduced labor process for harvesting or transferring fish from large and deep circular culture tanks.
5.Significant Activities that Support Special Target Populations
Technical support in aquaculture engineering, fish health and biosecurity has been provided to rainbow trout, Atlantic salmon, tilapia, and cobia producers across the Appalachian region. This work supports economic development in a region where many counties are rated as economically distressed and unemployment rates are greater than 10%. Across the Appalachian states of West Virginia, Kentucky, Virginia, Maryland, and Pennsylvania, there are many natural resources that appear to represent potential development opportunities.
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