Farming in closed facilities
A closed tank or net provides full control over everything that enters and exits. This gives control over the environment and greater opportunities for the growth, health and wellbeing of the fish. Salmon lice, escapes and unwanted emissions can in principle be eliminated in a closed facility.
Closed facilities on land are used today for smolt weighing up to 100 grammes before the fish are put out into saltwater. Several closed facilities have now also been implemented in which the fish are kept beyond the smolt stage. This provides a more robust fish and results is reduced mortality.
Different solutions are being tested and trialled, both as fully and partially closed systems at sea and on land, with different materials such as concrete, fibreglass, steel tankers and mash etc.
The work especially involves fish weighing between 100 and 1,000 grammes (post-smolt). The challenge is to find a method that functions for larger fish without this meaning a substantial increase in energy use, a deterioration in fish health and reduced fillet quality.
So far, it seems that the salt content and the water throughflow are the critical factors for good fish health in closed facilities.