Location: Cool and Cold Water Aquaculture Research
2011 Annual Report
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.
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.
The ADODR is in frequent contact with the cooperator through phone calls, email, and site visits in addition to receipt of written reports.