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Canadian RAS, hybrid farm tech commercially ‘ready,’ says DFO

February 5, 2020  By  Nestor Arellano

A long-awaited study by Canada’s Department of Fisheries and Oceans (DFO) indicates that the country’s recirculating aquaculture systems and hybrid farm technologies are ready for commercial development.

The 64-page report, titled State of Salmon Aquaculture Technologies 2019 was expected to be released some 12 months ago but it was only made public today.

The DFO examined four alternative technologies: RAS, hybrid, floating closed containment systems, and offshore open-ocean systems. The study found only RAS and hybrid fish farm technologies were more advanced than the other technologies the government investigated.


“All four systems offer multiple improvements over today’s conventional net-pen production systems,” the study said. “…Land RAS and hybrid production technologies are ready for commercial development in BC while floating containment and offshore production systems need up to five years and 10 years respectively to evaluate their potential.”

The study also noted that several things need to be aligned in order to promote innovation in Canada and to position B.C.’s salmon aquaculture sector for growing global seafood export opportunities.

These included: national legislation and policy that will “clarify the requirements for aquaculture in terms of environmental and social performance and this will send the appropriate signals for investors to develop the technologies that meet the challenge.”

In October last year, shortly before the Liberal government of Justin Trudeau won its second term, the prime minister unveiled a controversial plan to replace British Columbia’s open net-pens with land-based salmon farms in the next six years.

The plan was opposed by many net-pen operators and said it was “unachievable.” The policy was labeled as “high irresponsible” by The Canadian Aquaculture Industry Alliance.

The study’s positive reference to hybrid technology could bode well for the net-pen industry.

Many salmon farmers in B.C. have been testing out hybrid systems. The method reduces the amount of time fish spend in open water.

BC Salmon farmers have already been exploring hybrid systems, which simply reduces the amount of time fish spends in the open water. And one small RAS system, Kuterra, has successfully operated as a proof-of-concept. Kuterra LP also has a RAS facility for salmon in Port McNeil, Vancouver.

Currently, about 98 per cent of global salmon production comes from open net-pen systems in sheltered and exposed in-shore environments (about 94 per cent of B.C. total).


Land-based RAS involves growing salmon in tanks on land in closed buildings to maintain an environment that is highly controlled and secure. The water intake is treated with an ultraviolet light or passed through special filters to prevent disease and contamination that could affect fish health. Upwards of 99 per cent of the water is re-circulated on each cycle through the system.

Some RAS systems produced up to 1,000 mt of salmon annually. Other systems being constructed have the potential to produce 3,000 mt or more.

“High capital costs have led to larger facilities being built to gain efficiencies of scale. The larger facilities employ modular designs to reduce risks associated with component failures or contamination events,” the report said.

The study also noted several challenges with RAS technology:

  • Fish quality  – Managing the system to avoid off-flavours is an on-going key topic for RAS producers.
  • Fish health – Microparasites and water compounds such as sulfides that can reach toxic levels. Control measures including water intake and recirculation filters, construction materials, anti-fouling agents, ozone treatment, and fish waste management are all important areas of research
  • Broodstock development – This will focus on gender advantages, triploidy, late maturation, tolerance to high stocking density and low oxygen
  • Large tank design- There is ongoing research to optimize water velocities, placement and design of nozzles, and other measures to achieve proper distribution of oxygenated water and collection of waste in larger tanks of different shapes
  • Energy efficiency- Improvements in water pumping, filtration, lighting, heating and cooling, and other system components and functions will continue to gain efficiencies while maximizing fish welfare and performance
  • Feed formulations – New developments aim to meet sustainability criteria with alternatives to fish meal/oil ingredients that are suited to land-based RAS needs including efficient waste collection. For these systems, this must not hinder biofilter function or off-flavours.
  • Stocking densities –This impact water flows in tanks, fish health, and welfare, revenues, loads on recirculation system components.
  • Design and construction efficiency- Given the high impact of capital costs on the viability of these systems, there will be continued efforts to find more cost-effective designs and construction techniques.


The hybrid approach involves producing post-smolts weighing from 250g to 1kg. The land-based portion provides better growing conditions and reduces early growth phase risks at sea. The shortened grow-out period reduces some environmental risks at marine sites and avoids the most costly portion of land-based systems in the grow-out phase, according to the report.

Current hybrid technology development is focused on finding the appropriate size of post-smolts for transfer to sea as a number of factors are considered in order to optimize the use of the land and marine production systems, the report said.

Challenges with hybrid systems include:

  • Land-based requirements – Hybrid systems have some requirements equivalent to those already discussed for land-based systems. For example, so water intake and discharge requirements may lead to different facility locations (adjacent to the sea rather than inland) compared to some land-based RAS hatcheries that are using freshwater only
  • Transfer to marine sites – This will be similar to conventional transfers today, however, the stress of fish at larger sizes is being studied to optimize procedures. New larger vessels (not only for transfers) are being designed to service marine sites and coastal infrastructure must be developed to support these
  • Sea lice – The use of marine net-pens for grow-out will continue to require methods for addressing sea lice, although the sea lice presence and outbreak risks are greatly reduced with larger post-smolts spending less time in the marine environment
  • Algal blooms – Blooms may persist as a problem for open net-pens. Although insurance can cover some losses, this ultimately comes at a cost to operators. Oxygenation and aeration diffusers for structured upwelling (also to prevent sea lice) are promising to be effective for algal blooms.
  • Other environmental impacts- Wildlife interactions, escapes, waste effluent, and other environmental issues associated with marine net-pen sites will continue to be a focus of research efforts

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