Freshwater focus
RAS
THE Conservation Fund’s Freshwater Institute (FI), a global leader in recirculating aquaculture system (RAS) research and development, will be hosting a full session at the RAStech conference in Washington DC this May. Entitled ‘Freshwater Institute Research Update:A Holistic Approach to Fish Production in RAS’, the session is designed to highlight a range of important aspects for RAS facilities, including engineering, fish health and biology, production system management and operation, fillet and product quality attributes, wastewater treatment, economics, and more.
The FI team will be in attendance to present recent work encompassing these topics. Many of the talks will centre on research evaluating Atlantic salmon production in RAS, a focus driven by increased interest and rapid investment in this industry sector in the US and abroad.
Director of research, Dr Christopher Good, will kick off the session with an overview of FI’s multi-year collaboration with CtrlAQUA, Norway, a partnership specifically designed to study RAS based salmon production.
FI’s focus in the CtrlAQUA research programme is post-smolt Atlantic salmon production and grow-out in freshwater RAS, while European scientists are evaluating smolt production in land based systems in support of the existing salmon farming industry.
FI’s research facility in Shepherdstown, West Virginia, houses a semi-commercial scale RAS and replicate experimental systems where research with a variety of aquaculture species, including Atlantic salmon, is carried out.
FI’s focus on Atlantic salmon grow-out in freshwater RAS is unique and somewhat unconventional, but the research has proven that it’s biologically and technologically feasible to raise salmon to market size with this approach.
A likely advantage of Atlantic salmon production in freshwater is that it expands the possibility for siting land based RAS facilities to locations away from the coastline and closer to major markets.
John Davidson, research scientist at FI, said: ‘If you have access to a viable freshwater supply anywhere in the US, you can potentially grow Atlantic salmon there.’
However, he is quick to point out that Atlantic salmon production in freshwater RAS has not been without challenges.
FI has experienced a relatively high degree of early maturation during some of their Atlantic salmon grow-out trials.
Salmon maturation is a highly flexible process that is influenced by many factors, such as photoperiod, water temperature, and genetics.
FI researchers are diligently working to define the right combination of conditions to limit early maturation, which causes downgraded fillet quality. Experience with early salmon maturation will also be described by FI staff at the RAStech meeting.
Questions still remain in this relatively new frontier of salmon farming, but FI is poised to help the RAS industry and its stakeholders.
A core competency of the Freshwater Institute programme is its research, development, and engineering of RAS technologies, which will be on display at RAStech.
Research associate Christine Lepine will present research entitled, ‘Woodchip bioreactors for treating RAS wastewater: Evaluating performance, economic feasibility, and environmental impact’.
This presentation will demonstrate adoption of a farmer friendly technology used in tradi-
“Questions still remain in this relatively new frontier of salmon farming”
tional agriculture for denitrification treatment of RAS effluents. Engineering design metrics, including optimal hydraulic retention time, inlet design, and nutrient removal efficiencies will be discussed.
Also related to the development of next generation technologies, John Davidson will describe integration of membrane biological reactors within the water recycle loop of RAS.
His research indicates that this advanced waste treatment technology can reduce water use and waste discharge by six to seven times compared to traditional RAS, while maintaining suitable culture conditions for salmonids.
Further reductions in water use and waste discharge are potentially important aspects to consider with the growing scale of salmon RAS facilities.
Other presentations with overlap to RAS based salmon production will also be provided, including a talk by assistant aquaculture production manager Curtis Crouse entitled, ‘Practical problem solving and management techniques to address RAS challenges’.
This talk will offer insights into select tank side challenges that FI fish production managers have encountered, along with innovative solutions that have been developed to solve these problems.
In addition, an overview of FI research on off-flavour remediation techniques, humane slaughter, and Atlantic salmon product quality will be provided.
To close out the list of FI talks, project engineer Laura Bailey will present an analysis of economies of scale for land based salmon RAS, evaluating capital costs for production scales from 1,200-3,600 tonnes.
Salmon RAS facilities that are currently being planned or constructed are large, ranging from 1,000 tonnes up to > 30,000 tonnes.
This final presentation will provide insight into the relationship between economies of scale and production costs of salmon RAS facilities.
The session will conclude with an open panel question and answer forum, where FI staff will be available to answer questions about their work: past, present, and future.