color with brown and black spots with the ventral side being tan to yellow. The sides have many orange and red spots ringed with a light blue. Life cycle Their average length is 60 cm, but they can grow up to 130 cm in length and weigh up to 20 kg under favourable habitat conditions. Their most striking feature is the long, elongated, torpedo-shaped body. They have silver grey sides and grey-green backs. The belly is white. Like all trout species the sea trout has an adipose fin. Sea trout feed mainly on fish, small crabs, shrimps and prawns. It is an anadromous, migratory fish, which closely resembles the Atlantic salmon in its form and lifestyle. In the sea, it makes long journeys and also swims upstream into small rivers in order to spawn. Spawning occurs in winter on gravelly river beds in the grayling zone to the barbel zone. Their eggs are laid in troughs or redds. The young fish remain in freshwater for one to five years and then make their way to the sea. The "inner clock" signals to the fish when they need to make their return journey to the sea. During this migration, they can cover up to 40 km per day. Fish that are ready for spawning are usually lean and have to eat a lot of food in order to increase their energy levels as quickly as possible. After completion of the spawning process, the fish return to the sea. The mass mortality after spawning that is common in some species of salmon is not usual for brown trout. Once back in the sea, the fish regain their weight and lose their brown spawning colouring. The surviving young of sea trout will generally migrate back to the sea, to feed in estuaries and coastal waters. However it is also known that adult brown trout, which may have spent some years entirely in a river, can for whatever reason decide to migrate to sea, to return next year as a much larger (sea) trout, with silver colouration. Threats In many rivers of Central Europe, the sea trout have been extirpated because hydropower plants prevent spawning migration. In addition, many spawning grounds have disappeared due to the backflooding of rivers. In more recent times, sea trout have succeeded in re-establishing themselves in some lakes and rivers through the introduction of fish ladders and bypass channels