Sea trout can be found all around the British Isles and Ireland, but for guaranteed sea trout sport head for the west coast of either England, Scotland, Wales or Ireland as the runs of these fish are the most prolific in those areas.
They enter our freshwater river systems between April and September, swimming many miles upstream to breed. They will use lochs and loughs to further their journey to the cleanest, pure upland rivers.
The sea trout is, in fact, a migratory brown trout that spends a great deal of its time in the sea. They both share the Latin classification Salmo trutta.
In terms of their shape, sea trout are identical to brown trout, but when the sea trout nears freshwater upon its migration it has a silvery appearance. There are numerous spots along the flanks, down to a line that is level with the base of the pelvic fin.
The colour of the adult sea trout darkens as it journeys through freshwater – then it’s even harder to distinguish a sea trout from a brown trout – the only real way to tell the difference is to look at the spots. Brown trout have red spots, while sea trout have dark spots.
Sea trout only feed when they are in the sea. Here they eat crustaceans, shrimp, prawns and small fish. They are particularly fond of sandeels.
To catch a sea trout you have to antagonise it into taking a bait, by either using plugs, worms, prawns or flies.
Sea trout usually breed between October and the end of the year. They breed in shallow, gravelly, pure and well-oxygenated rivers well upstream from the sea.
The young sea trout go through the usual salmonid life cycle of egg, alevin, fry and parr. This can take up to two years.
Once the parr reaches adulthood it changes and takes on a silvery sheen, then migrates to the sea. At this stage the young sea trout are called smolts.
Some smolt spend only a few months at sea and return to freshwater, and the remainder return to breed the following year.