Brown trout (Salmo trutta) and sea trout are in actual fact one and the same species. In some cases the trout will stay in freshwater and in other cases it will become migratory and then follow a pattern of life similar to salmon. In this way the sea trout grows to a greater size than is normal with brown trout, doing so by the excellent feeding in the sea. However it will return to quite small rivers and surprisingly small brooks. The forms of trout tend to breed true, that is the offspring of sea trout parents produce sea trout. However in the wild, cross breeds mean that the forms normally thought of as brown trout can if required as a result of deteriorating freshwater conditions choose to go to sea.

Sea trout are common in the rivers systems of much of Europe and many years ago were introduced and spread well in South America. However it is the dominant species of salmonid in a system that sustains the sea run so for example although brown trout are quite common on the Atlantic coast of North America it is the brook trout that takes on the migratory role, in the same way the rainbow trout becomes the steelhead on the west coast of America. Sea trout don't always return to the exact parent stream but usually do prefer the parent system. Wales, Scotland and Ireland are the main sea trout areas around the British Isles. Spawning occurs in gravel "redds" in the Autumn, the females prepare in October and look for and try out suitable redds and pair off with males. Day length appears to be a key trigger mechanism and water temperature effects the length of the process. Specific areas are chosen year in and year out and the condition of our rivers are key to good stocks, particularly clean silt free highly oxygenated streams. The fish choose stable gravel areas with gravel of around .75 to 1" diameter and in about one foot of water located in small tributaries usually about ten feet wide. The female cuts the redd by vigorous spasms of movement from side to side mostly at dusk. When the redd is ready the male and female position themselves alongside each other and the stream of eggs are fertilised by a cloud of sperm. The current pushes the eggs into the depression of the redd and the male moves away while the female lashes the gravel back over the eggs.

Many females and males can be at work in a communal Redd. By the end of December the spawned adult fish (kelts) will have moved back to sea. The eggs incubate through Winter and are hatching in early spring as Alevins which become fry. The fry move away from the gravel and downstream into slacker water to take nymphs and other food that pass by. More than 90% of the fry die mainly as the result of predators such as other fish but also birds. While some birds are in reasonable balance with the stock, there is a major problem with Cormorants and Merganisers. However the really serious problem occurs when the fish get to sea as seals which have massively increased in population taking large numbers of fish that far exceed fish caught on the fly. The fry are known as fingerlings at about 3 to 4 months and have parr markings like finger prints. They will move further downstream and feed on nymphs, caddis, snails and small fish fry as well as caterpillars and insects. By their first winter they move into the pools and take up spots next to a deep bank of stones where they become less active until the warm weather returns, by the summer they will be about 5 to 6" in length. At this point they will start to change from being identical to brown trout and become silvery and move into the lower reaches of the river for their second winter.

The larger ones will become Smolts who go to sea to feed, but others may hang around in the estuary or go back upstream to grow further before going to sea. In colder latitudes the process could take up to 5 years as opposed to 1 year in the South of England. When migration starts they will drop downstream often at night in high water conditions in the spring.



At sea the sea trout tend to remain close to the coast and often stay near their rivers. Larger ones may travel larger distances along the coast and are caught by commercial nets. They eat other small fish and sand eels and in productive areas such as around the coast of mid Wales gain weight rapidly. Most of these fish return to the river within months and are often referred to as Finnock who shoal into the river in June and July. Depending on the locality these fish can be quite small say around 10oz but in other areas they come earlier and the early fish can be quite big at 2lbs. The process is repeated and fish that have spawned three or four times will tend to weigh about 6 to 7lbs.

Salmon are confused by some anglers with sea trout, particularly when they are fresh-run. Sea trout have thicker tail wrists and in keeping with brown trout it is hard to hand tail them. Sea trout feel smoother having more and smaller scales, a scale count (from rear of adipose fin to lateral line) is fourteen. The sea trout has more spots and tends to have a flatter squarer tail. Sea trout differ from Salmon in more ways than appearance as they can feed in freshwater and will take a lure at night.

Fishing in Darkness
First, it is worth mentioning the importance of safety. Rivers can be dangerous at daytime but with the added burden of darkness special precautions should be taken. It is almost essential to know the river before attempting to fish it at night. If you are on holiday, when much sea trout angling occurs, then visit the river during the day and plan your nocturnal visits. Be on the look out for deep holes in the river bottom, large rocks, steep banks, boggy areas and other hazards. On the night in question you are likely to be there just before dusk so you can again check the terrain and think through your plans. A torch is essential. Some anglers choose to buy a small adjustable torch that can be clipped to a waistcoat. For the most part do not wade at night though. The ideal night for sea trout angling is with a moon but with overcast conditions. Bright moonlight is less productive and the anglers movements are more likely to be observed anyway. Pitch blackness with no moon can be uncomfortable for fishing and the productivity of such conditions are debatable. As for the times, between dusk and midnight is productive and is usually fished with flies close to the surface. After this it is best to switch to a well sunk fly on a sinking line although from time to time a surface fly should be tried, one that sits on the water and creates a good wake.

t will have become apparent therefore that sea trout are difficult to catch during the day and they are the most wary of fish. Although freshly run fish are active by both day and night they are most active immediately after darkness descends and at dawn. The longer they are in the water the more they take up particular lies. In heavy water conditions sea trout tend to be more active during the day and all may be quiet during the night. Sea trout can be divided into certain types by their taking potential. Traveling fish in June and July are identified by their wakes as they push upstream even in low water and they show little interest in the fly. They will only take when they start settling down in a particular pool. These fresh fish are sometimes called cruisers and move around a pool. Likely spots are the 'tail' of the pool as the dusk turns fully dark. Do not be afraid to cast over very shallow water as sea trout seem to like shallow areas so long as they are not spooked. The head of the pool should also be tried. Sea trout don't really feed in fresh water although they exhibit feeding behaviour and respond to hatches of naturals, particularly where they are abundant. However a more consistent fishing method involves fly patterns which lure as well as imitate naturals.

The best rod for sea trout fishing is the trout rod you are used to so long as it is not too light. Usually a floating line is best and the fly should be fished slightly under the surface with the cast sunk. The best approach, as I would say for most fishing, is to fish near the bank first and work the fly out with each cast to cover more water. There are two benefits here in that if you are quiet you will cover close fish and even if the pool has been fished it may have been done so from the far bank, pushing the fish to your side. Sea trout are wily creatures so it is good practice to proceed with caution, in due course many of the fish will move to the far bank and then it is there alone that most takes will continue to be made. Covering the area towards the tail of the pool you can cast slightly upstream and let the fly work round. Generally speaking attempting to mend the line can be more trouble than good because of the disturbance but also because sea trout can be attracted to a fly streaming away from them, particularly those fish freshly arrived in the pool. As with brown trout fishing it is a good idea to allow the fly to swim for a moment as it goes downstream of you. It is also worth retrieving it towards you a little bit before lifting off to cast. Sea trout can take very abruptly and can make powerful runs and jumps, they are the most sporting of all fish. When a fish is hooked make a quick note of where you intend to land it and how. Size and conditions dictate here but if you can beach a fish it is often the best method. During the fight keep the rod high and maintain a steady pressure, do not allow the fish to pull line away too freely if they run as they seem to sense escape and take advantage of it. In darkness problems of tangles and overruns are even more problematic, so try to fish in a tidy fashion and once the fish settles into the fight, retrieve loose line onto the reel and keep loose line to a minimum or play the fish off the reel.