SEA trout are genetically the same as brown trout, the only difference being that they decide to migrate to the sea to feed. Brown trout may also migrate to different parts of a river or lough to feed. They are anadromous fish in that they breed in freshwater but feed at sea.
Sea trout can grow to weights in excess of 20lbs and this depends on water temperature and food sources. They are known as sewin (Wales) and white trout (Ireland), with young immature fish that spend only a few months at sea often referred to as finnock or herling.
They are found in both the northern and southern hemispheres, with the sea trout from the Rio Grande (Argentina) and the Falkland Islands probably the largest. Most sea trout are female and around 75 per cent survive spawning.