Cages can be places in rivers or in the sea. They are anchored to the seabed and are located in areas that are protected from storms and high waves. Because the cages are in open connection to the surrounding water, diseases and parasites can easily be spread from farmed to wild fish and the other way around. Chemicals, medicines and faeces are coming directly in the surrounding water. Farmed fish often escape because the nets damage easily. Most salmon is farmed in this type of system.