2012 Annual Report
1a.Objectives (from AD-416):
Recirculating aquaculture systems (RAS) provide control of water quality and temperature to optimize fish production and health, provide barriers that prevent escape of fish and entry of pathogens, contain and remediate waste flows to curtail environmental impact, and minimize water use. RAS can allow a commercial fish farm to locate where power, feed, or oxygen is relatively inexpensive, where environmental impact can be minimized, and/or adjacent to their primary markets. However, RAS are dependent on relatively larger energy inputs than traditional flow-through or net-pen systems. Thus, strategies are required for reducing energy consumption and improving waste disposal, which both are major factors in a fish farm’s overall life cycle assessment. In addition, production techniques must be developed to improve biosecurity and reduce stress and disease outbreaks in fish cultured in closed containment systems. This work will integrate research and technology advancements, and resolve current and emerging constraints to the expanded use of land-based, closed containment systems for the production of safe and nutritious salmon and other cool- and cold-water species.
Objective 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.
Objective 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.
Objective 3: Conduct production trials of fish and feeds developed through ARS collaborations.
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.
The overall goal of this project is 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.
Research on Atlantic salmon performance, health, and welfare, plus system water quality, was carried out in replicated water recirculating systems that were operated at either high makeup water (2.5% flow exchange) or low makeup water (0.25% flow exchange) flushing rates. This work has provided valuable information to producers intent on rearing Atlantic salmon in closed-containment systems up to market size in fresh water.
A sidewall box containing a forced-ventilated cascade column and low-head axial flow pump was developed and found to provide a more cost and energy effective method for adding oxygen to and removing carbon dioxide from water recirculated back into the fish culture tank. As a result of this positive analysis, this technology 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.
We compared 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 water recirculating systems operated at low flushing rates.
Selected Atlantic salmon (NCWMAC, Franklin, ME) germplasm resources, one group diploid and the other triploid, were received as eyed eggs, hatched, and cultured to parr. After smoltification, these diploid and triploid salmon will be evaluated during growout within intensive water recirculating systems.
We employed 454 pyrosequencing toward characterizing intestinal microflora of rainbow trout fed grain- or fishmeal-based diets and raised at high or low densities. The novel discovery of a core intestinal microbiome that appears resistant to changes in diet and density will assist aquaculture nutritionists in formulating new diets that are both environmentally sustainable and fish performance-enhancing.
We evaluated the effects of chronically elevated nitrate nitrogen on rainbow trout
performance, health, and welfare. Findings are critically important in establishing
boundary design criteria for rearing system water quality in tightly closed recirculating systems.