I lukkede anlegg kreves full kontroll med kvaliteten på vannet som går inn og ut av anlegget. Nofima har et forskningssenter der 99 prosent av vannet resirkuleres. Foto: Kjell Merok/Nofima

Aquaculture in a controlled environment

Full control is a vital concept for the sustainable intensive production of farmed salmon, with good fish welfare and a minimum of risk. We are working at Nofima to achieve full control of the environment in which fish live. This enables the full growth potential of the salmon to be realised, and reduces production costs.

Aquaculture in a controlled environment is a concept that emphasises that it is the facility personnel who control the environmental factors, and not random environmental factors that control the salmon. In order to control the environmental factors, the facility personnel must be able to control the water that enters and leaves the facility. This means, in practice, that a closed-containment aquaculture system must be used. Experiments carried out by our scientists have shown that closed-containment systems give better control of the fish environment, and good management here gives higher water quality, growth and welfare than can be achieved in traditional facilities.

Closed-containment systems are particularly suitable in salmon aquaculture in order to gain better control of environmental conditions, sea lice, and escapees.

Quotation: “Postsmolts are salmon who are adapted to life in sea water, and have been kept in this environment in a closed-containment system until they weigh around a kilogram.”

Closed-containment systems have a sealed, or nearly sealed, physical barrier between the water in which the fish are kept and the surroundings. They may be closed-containment systems on land with recirculation of the water, or floating semi-closed systems in the sea. Closed-containment systems are particularly interesting for those who want to produce postsmolts weighing up to around a kilogram, avoiding high levels of sea lice and high fish mortality. Although escape can occur also from closed-containment systems, such systems are likely to prevent escape better than traditional cages in the sea.

Biological requirements

Closed-containment aquaculture systems, however, cannot guarantee success on their own. There is a risk of falling into a trap here, unless it is ensured that the farmed fish have good living conditions. The pitfalls of using closed-containment systems may be just as large as the advantages if it turns out that in the enthusiasm over solving one set of problems one experiences a sequence of new ones due to inadequate knowledge about the changed biological requirements of salmon in this new environment.

This is why we are working at Nofima to test new technology in aquaculture, and we carry out research into the environmental conditions that salmon require in order to achieve optimal growth, welfare and survival in closed-containment systems. It is crucial to satisfy the salmon’s requirements if new technology is to be successful.

Examples of technology research we carry out in closed facilities:

  • development and testing of complete systems
  • water-treatment processes, sensors and control systems
  • removal of particles from waste water and the utilization of sludge

Results from our research

Several good examples showing that our research in environmentally controlled aquaculture is beneficial can be given. Just as humans, salmon in the postsmolt stage benefit from less salty water and more exercise. Experiments in closed-containment systems with water recirculation have shown that a salt level of 12 ppt is optimal, and that exercise is beneficial for the fish. These conditions improve growth, welfare, skin health and survival in the postsmolts, and give a more efficient cleaning of the water in the recirculation system. Industrial partners are now continuing these tests on a large scale.

Our research has shown that the currently used guideline for the amount of ammonia that salmon tolerate may not be suitable for future smolt production in closed-containment systems. If the limits are set unnecessarily low, new facilities must either be dimensioned with unnecessarily large biofilters or they must use unnecessarily high flow rates through the biofilters. This makes the systems more expensive to construct and operate than necessary. We have measured the tolerance of the fish for ammonia, and did not find negative effects on the growth or health of the fish until high concentrations were reached.

Research at Nofima into technological solutions and the welfare of fish in closed facilities has contributed to the aquaculture industry now primarily building fish hatcheries with recirculation systems.

We offer:
  • Problem-solving in our facility at the Nofima Centre for Recirculation in Aquaculture (NCRA) at Sunndalsøra
  • Test of prototypes of facilities or components, their effects on fish and on water quality. Several large-scale projects are under way in which we carry out thorough tests on such factors as water quality, growth, skin health and welfare.
  • Aid in reducing production costs in closed-containment systems on land and in the sea
  • Aid in providing good growth conditions for fish
  • Fundamental studies on the recommended concentrations of carbon dioxide, ammonia, nitrite, salt and water flow rates
  • Large-scale trials using new technology at client facilities
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