Location: Cool and Cold Water Aquaculture Research2011 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
The goal of this project is to develop and improve technologies enhancing the sustainability of the modern aquaculture industry (NP106 Component 5), this year significant progress was made under Objective 1. A low-head and high-flow aerator pump mounted directly against the side of the culture tank was found to provide efficient O2 transfer and CO2 removal, which effectively increases carrying capacity of the culture volume. The fixed and variable costs for two types of partial water reuse systems were estimated and compared for trout culture. The partial reuse system using sidewall box airlift pumps at each culture tank reduces fixed costs by approximately 37% and electric and oxygen costs by as much as 54% compared to more conventional partial water reuse technology. The sidewall box airlift pump can therefore be integrated into the design of larger recirculation aquaculture systems (RAS) to improve gas control, provide culture tank rotation, and reduce total power requirements. To investigate improving the fish rearing environment through use of water ozonation, we compiled the results from three studies conducted in our six replicated RAS that were either operated with or without ozone at various water exchange rates. Ozonation of recirculating water in systems operated at the same low water flushing rate was found to improve fish growth while significantly reducing suspended solids, biochemical oxygen demand, copper, iron, and color concentrations in the culture tank water. In addition, water quality and fish growth were similar within ozonated systems operated with low water exchange as compared to the same systems operated without ozonation but with 10-times more flushing. Thus, ozonation improves water quality and fish growth and survival in production systems that must operate in environments where water use is restricted due to water availability, temperature control, or pollution abatement requirements. The effects of elevated nitrate nitrogen (NO3-N) on rainbow trout performance, health, and welfare are being examined in a controlled and replicated study. Fish are being raised from 15g-150g and exposed to either elevated (~100mg/L) or normal (<30mg/L) NO3-N concentrations. Outcomes being examined include survival, deformities, side-swimming, swimming speed, and fin condition, and their association with elevated NO3-N is being investigated. The study is currently nearing completion; findings will be important in establishing boundary water quality criteria in tightly closed RAS.
1. Swimming speed and dissolved oxygen (DO) concentration affect Atlantic salmon performance. Exercise has been shown to enhance salmonid performance, but DO levels can be limiting. Hence, there is a need for research optimizing swimming speed and DO parameters. Scientists at The Conservation Fund’s Freshwater Institute (TCFFI) determined that for Atlantic salmon; mean weight was significantly enhanced by both higher DO levels and swimming speeds, and exercise significantly reduced the prevalence of precocious males which have negative impacts on production. Increased performance and reduced precocity in industry can therefore be achieved through exercise and supplemental DO.
2. Atlantic salmon health and performance unaffected by high carbon dioxide (CO2) concentrations. For freshwater closed containment grow out of Atlantic salmon to succeed, safe water quality criteria are not well-defined. Elevated CO2 can negatively affect fish performance; however, scientists at TCFFI raised Atlantic salmon for 12 months at either high or low CO2 concentrations, and observed that performance and survival were comparable between treatments. Atlantic salmon can therefore be raised safely to market size at relatively higher concentrations of CO2, and increased pumping of water to control CO2 at higher levels is unnecessary.
3. Atlantic salmon strain and photoperiod treatment affect time-to-market and early maturation. Although certain strains of Atlantic salmon have anecdotally performed well in freshwater grow out systems; whether or not photoperiod manipulation is necessary to produce smoltification needed testing. Scientists at TCFFI showed that growth in both strains (Gaspe and St. John) was enhanced with a 6-week winter photoperiod. The Gaspe strain grew faster overall, had lower early maturation, and had a higher dress yield and fillet fat content than St. John fish. This information is being used by farmers to develop a broodstock program to support freshwater salmon production.
Davidson, J., Good, C., Welsh, C., Summerfelt, S.T. 2011. The effects of ozone and water exchange rates on water quality and rainbow trout Oncorhynchus mykiss performance in replicated water recirculating systems. Aquacultural Engineering. 3:44:80-96.