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By Suzi Dominy*

Feed is key to the advance of RAS production

Recirculating Aquaculture Systems (RAS) are not new and still represent a small segment of aquaculture production, but it’s a rapidly trending technology and the industry’s hot topic.

Drivers for its future growth are its apparent low environmental impact and the proximity to market for high-value species, affording both economic and biosecurity advantages.

RAS presents challenges and opportunities in every aspect of production, from genetics to systems engineering, and not the least of them is the management of the system biomean area that is inextricably linked to feeds. Most of the major feed companies are devoting research efforts to the development of RAS feeds.

Biomar, for example, is contributing to a new European research project, RASbiome: Microbial management in RAS for sustainable aquaculture production, funded by ERANET BlueBio, which aims to improve the sustainability of fish production in recirculating aquaculture systems (RAS) by introducing new and innovative approaches for microbiological water treatment.

“BioMar is providing the feeds for biological trials on rainbow trout juveniles run by DTU Aqua.”

The different diets in the trials will be varying carbon-to-nitrogen ratios, an essential parameter for microorganism performance. The expected sustainability outcomes of this project for aquaculture production are improving fish welfare and productivity due to stable and optimized chemical and microbiological water quality, reducing environmental impact through nitrogen removal from discharged water, and reducing operational costs.

The RASbiome project will focus on implementing two fundamentally distinct biological water treatment strategies, new to RAS, on improving the management of nitrogen compounds.

The first strategy involves anaerobic ammonia-oxidizing (anammox) bacteria, resulting in almost complete nitrogen removal from the water. This strategy excludes the need for external organic carbon. It entails reduced energy consumption and reduced CO2 production.

The second strategy takes advantage of biofloc formed by heterotrophic bacteria, assimilating nitrogen. This approach allows for harvesting sludge consisting of nutrient-rich microbial biomass. Therefore, it is compatible with the recovery and recycling of nitrogen from RAS water streams.

“BioMar, as well as all RASbiome project partners, truly expect the proposed project to give innovative outcomes on key challenges. New measures that can be applied in microbial water treatment, and especially in the management of nitrogen compounds, will undoubtedly promote sustainable fish production in freshwater RAS systems,” Pedro Gómez Requeni, senior scientist at the Nutrition Formulation Department of BioMar Global R&D said.

“Another approach was outlined by Tom Scrope, UK Manager of Nova Q Ltd., in our June 2021 issue of HATCHERY Feed & Management magazine.”

RAS aquaculture is not just about farming fish, but the biofilter bacteria too, he writes. “RAS managers recognize that bacteria are crucial to operating a RAS. But as long as adequate nitrification kicks in following “seeding”, most producers are inclined to leave the biofilter “well alone” for fear of disturbing the delicate balance.

While other aspects of RAS are being continuously improved, the functionality of the bacteria in RAS has not been optimized in the same way. To do things better, by definition, we need to do them differently”.

This lack of innovation has led to problems currently facing RAS sites, such as inefficient nitrification, including nitrite spikes, slow and unpredictable restarts particularly problematic for sites with short timescales before the introduction of fish to the system (e.g., research sites), hydrogen sulfide (H2S) spikes caused by sulfate-reducing bacteria being able to establish themselves in the system and off-flavor compounds (OFCs) in grow-out RAS reducing the value of stock and requiring expensive and inefficient “purging” to remove.

“Advances in the last few years in sequencing technology (especially 16S rRNA sequencing) need to be combined with innovative tools to influence the microbiome and positively solve the problems identified above.”

Some of these tools will involve a more considered use of inputs (e.g., feed) that impact the microbiome. But a vital part of the toolkit for any RAS farmer should be Active Microbiome Management. This advanced form of bio-augmentation involves directly influencing the biofilter microbiome through constant additions of beneficial bacteria.

This approach is already common in wastewater treatment (WWT) to avoid the system becoming dominated by “undesirable” bacteria. Many beneficial species are slow to reproduce.

By contrast, potentially pathogenic r-strategists (opportunists) can multiply much faster. Regularly adding large quantities of functional bacteria removes their slow reproduction rates as a limiting factor.

“Although good results can be achieved by experienced operators simply applying stabilized bacteria from a bottle, much more powerful impacts are possible using a bio-reactor grow tank to multiply and activate the bacteria before applying them to the system.”

Nova Q is currently adapting for RAS the BrewTus range of automated and purpose-built bio-reactors developed by their Canadian partners, with the installation of the first units expected imminently.

Sustainability news from

More than 70% of the greenhouse gas emissions produced by the salmon industry come from fish feed. Every year, the Norwegian salmon industry utilizes 1.6 million tons of feed, and 90% of the raw materials are imported.

The industry is calling for more environmentally friendly feed, and this will be one of the main tasks for the research center in Bergen, Norway. Researchers and the industry received the tools they need to develop the feed of the future with the opening of The Norwegian Aquafeed Technology Centre (ATC) in August.

The center will conduct open research, meaning that all industry actors will have access to the results and, therefore, the pace of innovation can be increased.

The research director at Nofima, Mari Moren, said that “it is not as simple as just removing soy and then adding new raw material. Firstly, research must be conducted on the suitability of raw materials in the feed pellet because feed production is rather complex. We have to start in the right place. Sustainable raw materials must first be processed in the correct manner before they can be used in salmon feed. Once this is in place, suppliers can start large-scale production.”

“ATC is a state-of-the-art center located at Nofima’s facilities in Bergen. The infrastructure and expertise offered are within bioprocessing, process technology, extrusion and feed technology, and analytical platforms.”

The Aquafeed Technology Centre’s new equipment allows studying the impact the processing of new raw materials has on the ingredients and the final product.

Nofima has also launched the Millennial Salmon Project to accelerate the development of sustainable solutions for the future of farmed salmon. The goal of the four-year project is to create the most sustainable-farmed salmon using novel ingredients from the circular economy and with a low carbon footprint.

With a €1.3 million budget, the project is primarily funded by the Research Council of Norway and is made up of leading organizations, Nofima, InnovaFeed, Corbion Algae Ingredients, Cargill, SINTEF Ocean, and Auchan. The project will study two alternative feed ingredients – protein-rich, insect-based feed ProtiNova from InnovaFeed, and algae-based omega 3s, AlgaPrimeTM DHA from Corbion, both of which offer minimal land use.

The evidencebased study will test the levels that are required to optimize the physical and nutritional needs of salmon, discover the practical and functional properties of both alternatives, as well as demonstrate the environmental and societal aspects of the suggested innovations.

“SINTEF Ocean will be conducting a life cycle analysis of the resulting Millennial Salmon feed.”

Aller Aqua became the world’s first fish feed company to achieve verification of CO2-labelling of fish feed. The verification process at its European factories was conducted by Bureau Veritas.

The company aims to create full transparency for its customers and particularly contribute to reducing CO2 emissions. Aller Aqua has recently taken other measures, such as replacing South American soy with regionally-produced soy in European factories.

A $2.2 million grant from the National Science Foundation has established the Center for Environmental Sustainability through Insect Farming. The Texas A&M College of Agriculture and Life Sciences has been assigned as the lead site for the center, which will be a collaborative effort with Mississippi State University (MSU) and Indiana University-Purdue University, Indianapolis (IUPUI). Joining the universities will be 34 U.S. and global industrial partners, including Mars Inc., Tyson Foods, and insect farming pioneers such as Aspire Food Groups, Protix, and Beta Hatch Inc.

*Suzi Dominy is the publisher of and Hatchery Feed & Management. She brings 30 years of experience in professional aquaculture and feed industry journalism and publishing.

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