Virtual tour to salmon farming

When the fish has gone through the physiological changes to become a smolt, it is then fit to tolerate the salty seawater without danger of dehydrating. The fish can now drink seawater and excrete salt through the gills.

In the spring the smolt, which is now between 80 and 100 grams, is placed in sea pens. A pen is a large net bag that hangs from a floating unit in the sea. The net is made of nylon threads. Weights are attached to the bottom of the pen to keep it stretched. The float has a fence to prevent the fish from jumping out. The float has to be well moored either to land or the seafloor. Pens are normally round, square or polygon with a diametre of 30 metres and above, and with a depth of 15-20 metres. The round pens normally are built of plastic, while the square pens are made of steel. Pens are often clustered together in groups.