Location: Cool and Cold Water Aquaculture Research2010 Annual Report
1a. Objectives (from AD-416)
1: Identify criteria to optimize the performance, health, welfare and consumer value of Atlantic salmon and other salmonids grown to food-size in intensive, land-based, closed-containment systems. • 1.1 Determine effects of high (20 mg/L) and low (10 mg/L) dissolved carbon dioxide concentrations on Atlantic salmon performance, health, and welfare during growout in freshwater RAS. • 1.2 Determine effects of strain and photoperiod manipulation (to produce smoltification) in a 2 x 2 factorial study on Atlantic salmon growth, processing attributes, and sexual maturity to 24 months post-hatch in freshwater RAS • 1.3 A comparison of rainbow trout performance and welfare in semi-closed (i.e., makeup freshwater supplied only to replace backwash flows) versus closed (i.e., freshwater backwash collected and reclaimed using MBR treatment) RAS operated with ozonation. • 1.4 Determine effects of swimming speed (2 body length/sec versus < 0.5 BL/sec) and dissolved oxygen concentration (70% versus 100% saturation) on rainbow trout performance and welfare. 2: Improve the effectiveness, energy efficiency, and economics of water reuse and waste treatment technologies and practices. This will include developing technologies to minimize waste and reclaim water, protein, and/or energy to improve the economic and environmental sustainability of closed-containment systems. • 2.1 Economic evaluation and life cycle assessment of land-based closed-containment systems for production of food-size Atlantic salmon and rainbow trout. • 2.2 Development of low-head and high-volume gas transfer processes to improve the energy efficiency of RAS. • 2.3 Improve technologies and practices that counter the effects of fish pathogens, and reduce the need for chemotherapeutic and antibiotic use within closed-containment production systems. • 2.4 Optimize cell age within MBR systems to maximize metals removal and protein content of waste mixed liquor suspended solids. 3: Conduct production trials of fish and feeds developed through ARS collaborations. • 3.1 Compare the effects of grain versus fishmeal-based diets on rainbow trout performance and welfare, as well as water quality, water treatment process performance, and waste production rates in RAS operated at low flushing rates. • 3.2 Field test selected rainbow trout (NCCCWA, Leetown, WV) or Atlantic salmon (NCWMAC, Franklin, ME) germplasm resources for performance in intensive recirculating aquaculture systems.
1b. Approach (from AD-416)
Research at The Conservation Fund’s Freshwater Institute focuses on developing and improving technologies to enhance the sustainability and reduce the environmental impact of the modern fish farming industry. To this end, the proposed projects listed in this plan will continue our work in pioneering land-based, closed containment water recirculation systems that are biosecure, have an easily controlled rearing environment, produce healthy and optimally performing fish, and produce manageable effluent for significant reduction in waste discharge. Specifically, our proposed research will investigate, among other things, the biological and economic feasibility of raising Atlantic salmon to market size in freshwater recirculation systems (as opposed to coastal net-pens); the potential for raising rainbow trout in semi-closed or closed water recirculation systems to further reduce the amount of influent water and point source discharge required for these systems; the health and welfare of salmon and trout in relation to dissolved oxygen and carbon dioxide levels, swimming speed in circular tanks, soy-based feeds, and water ozonation in low-exchange systems; and the potential for greater energy efficiency in water recirculation systems through improved low-lift pumping and gas transfer processes. In addition, our experimental systems will continue to serve as field testing sites for alternative-protein feeds and for salmon and trout strains selected through genetic improvement programs at other USDA facilities. The investigations proposed in this plan will build on the findings of previous years of USDA-funded research to develop a sustainable, environmentally responsible, and economically viable aquaculture industry in the United States. 1. Identify criteria to optimize the performance, health, welfare and consumer value of Atlantic salmon and other salmonids grown to food-size in intensive, land-based, closed-containment systems. 2. Improve the effectiveness, energy efficiency, and economics of water reuse and waste treatment technologies and practices. This will include developing technologies to minimize waste and reclaim water, protein, and/or energy to improve the economic and environmental sustainability of closed-containment systems. 3. Conduct production trials of fish and feeds developed through ARS collaborations.
3. Progress Report
This report documented progress for 1930-31320-001-00D which started 12/2/2009 and continued research from 1930-32000-003-00D. 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. Progress was made in several areas. Selected strains of Atlantic salmon and arctic char were subjected to two photoperiod regimes influencing smoltification, and are being reared to market size to determine strain performance and the effect of photoperiod manipulation on growth and product quality. The findings of this study will be used to provide valuable information to producers intent on rearing either or both of these species in WRAS up to market size in fresh water. Atlantic salmon are being raised to market size in freshwater WRAS operated at either high (20 mg/L) or low (10 mg/L) dissolved CO2 levels to obtain performance data that can be compared to similar data from saltwater net-pens, and to determine whether Atlantic salmon can perform as well in a relatively high CO2 environment. These findings will provide baseline data essential for designing land-based, closed-containment aquaculture facilities as an environmentally friendly alternative to coastal net-pens. Rainbow trout were raised to market size in replicated WRAS while being fed either a traditional fishmeal based diet or novel, alternative protein diet formulated by USDA-ARS scientists. These findings provided trout performance data for both treatment groups and provided novel data on the effects of soy-based diets on WRAS water quality and unit process treatment efficiency. A sidewall box airlift pump was developed to provide a new high water flow and low lift method of gas exchange just outside of the culture tank. A total of six different diffuser grids were tested within a pilot-scale 0.46 m square airlift pump. Water flow rates were measured, plus dissolved oxygen and carbon dioxide transfer rates and efficiencies. Providing an “angled-type” diffuser grid was found to increase water flow by approximately 60% over a ‘flat’ diffuser grid design. The “angled-type” diffuser grids were also found to transfer the most dissolved oxygen and dissolved carbon dioxide. The sidewall box airlift pump can be integrated into the design of much larger recirculating aquaculture systems to improve gas control, provide culture tank rotation, and reduce total power requirements and the carbon footprint of these systems. The effects of swimming speed and dissolved oxygen on rainbow trout performance, health, and welfare were examined in a 6-month factorial study, and this study will be repeated using Atlantic salmon. The findings of these studies will assist in optimizing the environment of farmed fish reared in circular tanks in order to improve fish production while minimizing health and welfare concerns. These studies have been and will be carried out in partial collaboration with fish health researchers at Nofima in Sunndalsora, Norway.
1. Successful applications of soy-based fish feed to rainbow trout in water recirculating systems. The interest and usage of alternative protein sources for fish feed is increasing as the aquaculture industry expands beyond the sustainable limits of ocean feed fish harvests. Experimental grain-based diets within three replicated water recirculating systems were tested by ARS scientists at Leetown, WV to assess fish growth rate, feed conversion, final size, and survival, as well as water quality, relative to these outcomes in fish fed traditional diets within three identical systems. No significant differences in rainbow trout growth, feed conversion, condition factor, or final harvest size were found between the two treatment groups. Although all water quality parameters tested were within safe limits, significantly higher concentrations of total suspended solids, carbonaceous biochemical oxygen demand, and total nitrogen and nitrate nitrogen were measured within systems fed the grain-based diet. These findings indicate significant progress toward a more sustainable grain-based diet as reflected by the comparable rainbow trout growth rate, survival, final harvest size, and feed conversion; findings also suggest that the recirculating flow should be ozonated to help reduce the suspended solids and organic carbon accumulation that can occur when using grain-based feed.
2. Identified factors affecting rainbow trout performance in circular rearing tanks. The relationships between fish growth and both dissolved oxygen levels and swimming speeds have been characterized individually, but not in combination. A factorial study, by ARS scientists at Leetown, WV, to identify whether swimming speed (2 body-lengths per second vs. 0.5 body-lengths per second) and dissolved oxygen levels (100% saturation vs. 70% saturation) affect rainbow trout performance or fillet yield was conducted. By end-of-study, after 225 days, mean weight of rainbow trout from all treatments averaged 838 to 1049 grams and was significantly affected by dissolved oxygen levels, i.e. the treatment groups receiving 100% dissolved oxygen saturation had significantly higher final weights than fish raised at 70% saturation. Increasing swimming speed did not significantly affect mean final weight, but did significantly increase mean fish cardiosomatic index, which has important implications concerning animal fitness. There were no significant differences between mortalities, fish length, feed conversion, or butterfly fillet yields among treatment groups. These findings indicate that circular tanks and oxygenation systems can be used to optimize rainbow trout growth and fitness by maintaining 100% oxygen saturation concentrations through the culture tank and swimming speeds of 2 body-lengths per second.
3. Rainbow trout health and performance unaffected in WRAS with low water exchange. Previous unreplicated research has indicated that in low makeup water / high feed loading WRAS, fish health declines for unknown reasons. This finding may have important implications for farmers using WRAS with very limited supplies of fresh water. Rainbow trout were raised for six months in replicated WRAS with either high makeup (2.5% exchange) or low makeup (0.25% exchange), by ARS researchers at Leetown, WV, to observe differences in fish performance, health and welfare. By study’s end, no significant differences were determined in growth, survival, and other measured fish health outcomes, although significant differences in a variety of water quality parameters were noted (none of these parameters, however, was outside acceptable ranges for raising salmonids). The results of this study illustrate that rainbow trout perform comparatively well even in low exchange, high feeding WRAS, and demonstrate that farmers with limited water resources can still remain competitive in terms of rainbow trout production.
4. Rainbow trout health and performance unaffected by dissolved carbon dioxide concentrations of 10 and 25 mg/L. Elevated carbon dioxide levels in aquaculture settings have been linked to poor growth, feed conversion, and reduced survival. At the same time, water pumping measures to increase tank exchange can represent significant cost to the producer both in terms of energy required for pumping and in fixed costs for equipment. ARS researchers at Leetown, WV raised rainbow trout in six replicated water recirculating systems for six months, exposing the fish to either high (25 mg/L) or low (10 mg/L) carbon dioxide concentrations. Performance, survival, and numerous fish health outcomes were unaffected by the high carbon dioxide treatment, i.e., there were no significant differences between the two treatment groups. The findings of this study demonstrate that rainbow trout can be raised to market size at carbon dioxide concentrations of 25 mg/L without detrimental consequences, and therefore increased pumping necessary to produce lower concentrations of carbon dioxide in water recirculating systems is unnecessary.
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.
Sharrer, M.J., Rishel, K., Summerfelt, S.T. 2010. Evaluation of a Membrane Biological Reactor for Reclaiming Water, Alkalinity, Salts, Phosphorus, and Protein Contained in a High-Strength Aquacultural Wastewater. Bioresource Technology. 101:4322-4330.