Sea Trout
Sea trout are the anadromous form of brown trout — the same species, but fish that leave their natal rivers as smolts, feed at sea, and return to spawn.
They run rivers across Wales, Scotland, northern England, and the West Country, and they're one of the most demanding freshwater quarry in the UK.
Night fishing with a fly on a Welsh or West Country river in summer is as close to a cult as British angling gets.
Scientific Name: Salmo trutta
Also known as Sewin (Wales), Peal or Peel (southwest England), Mort (northwest England), Finnock (Scotland, for first-return fish), Salmon trout (culinary)
- Fresh-run fish are bright silver with a white belly and sparse black spots — easily mistaken for a small salmon until you check the tail, which is square-cut rather than forked.
- Dark spots surrounded by pale halos appear above and below the lateral line; the upper jaw extends clearly beyond the eye.
- Most river fish run 1–4 lb, but double-figure fish are caught regularly on the Dart, Tamar, Spey, and Dovey; specimens over 10 kg have been recorded in Wales and Scotland.
- After time in the river, the silver fades to a darker, more brown-trout-like colour — fresh fish are the brightest and hardest fighters.
What to know
Habitat Distribution
- Native throughout the British Isles; anadromous populations run rivers along the Atlantic coast from Cornwall and Devon north through Wales, northwest England, and Scotland.
- Juveniles (parr) grow in the same acidic, gravel-bedded upland streams as resident brown trout before smolting and heading to sea, usually in late March or April.
- Returning adults hold in pools, runs, and estuary channels; they feed little once back in freshwater and are most active after dark.
- The River Ouse in Sussex is noted for producing the largest average-sized sea trout in England and Wales; the Tyne, Lune, Wear, and Ribble are the top-producing rivers in northern England by catch numbers.
Key Locations
- River Tyne (northeast England) — consistently the highest sea trout catch returns in England; the South Tyne runs crystal clear and fishes well at night.
- River Lune (Lancashire) — second only to the Tyne in northern England catch numbers; a classic spate river with good access.
- River Wear (County Durham) — smaller system than the Tyne but exceptional sea trout density per mile; night fishing is the local tradition.
- Afon Dovey / Dyfi and Afon Teifi (Wales) — two of the most celebrated sewin rivers in Wales, though both have seen runs decline from their peak years.
- River Dart and River Tamar system (Devon) — West Country rivers with a long tradition of peal fishing; the Dart's Totnes weir pool has produced double-figure fish.
Specific Spots
- Deep holding pools with a steady flow over the tail — sea trout rest here through the day and move onto the shallower glides and runs after dark.
- Pool tails and glides in low light: as darkness falls, fish spread from the deep water into the shallower, faster sections where a swung fly covers them well.
- Estuary channels and tidal pools on a rising tide, where fresh-run fish stack before pushing upriver — often overlooked but can produce numbers of bright fish.
- Weir pools and any natural obstruction that slows upstream migration; the Totnes weir pool on the Dart has historically produced large fish.
Sea Trout FAQ
Answers from onWater's species guide.
What are the best lures and bait for Sea Trout?
Small silver or gold spinners (sizes 1–3) and spoons are the classic spinning approach, the flash imitates the sandeels and small fish sea trout have been feeding on at sea.
What flies work for Sea Trout?
Large dark wet flies, patterns like the Teal Blue and Silver, Medicine, or Stoat's Tail (all slim, mobile flies tied on single or double hooks), are the backbone of night fishing, swung across the current on a floating line so they hang and pulse in the flow.
When is the best time to fish for Sea Trout?
First runs arrive in late spring on many rivers, with the main body of fish entering through June and July after summer spates. June and July are peak months on most Welsh and West Country rivers; northern English rivers like the Tyne and Lune often fish best from July into September.
How do you catch Sea Trout?
Night fishing with a fly is the dominant method across Wales and the West Country, where anglers wade familiar pools in darkness and swing wet flies or wake a Muddler across the surface. On northern English rivers like the Tyne and Wear, both night fly fishing and daytime spinning after a spate are widely practised.
What do Sea Trout eat?
Sea trout feed heavily at sea on sandeels, sprats, and small crustaceans, which is why silver or pearl-bodied flies and lures draw strikes even from fish that have stopped feeding in freshwater, the instinct runs deep.
See it in the app
Most maps show you water.
onWater shows you Sea Trout.
- 01 · Species map filter
Map every Sea Trout water
Pick Sea Trout and the map zeroes in on the waters they call home. No more guessing which lake holds them.
- 02 · Waterbody species
Tap any water. See what lives there.
Species, behavior and seasonal patterns for every lake, river and pond, before you leave the driveway.
- 03 · Angler Intelligence
Ask how to catch Sea Trout
Tactics, gear and timing from onWater's AI fishing guide, tuned to the species and the water you're on.
Stop guessing where Sea Trout are.
Open the map, filter by Sea Trout, and head to water that holds them. Download onWater and plan your next trip in minutes.
- Species map filter
- Angler Intelligence
- Fishing journal
Explore other species
Trout, bass, salmon, panfish and everything in between. Each guide unpacks the behavior, seasons, and tactics that put fish in the net.
No species information available.
Smarter Fishing Starts in the App.
onWater Fish gives you everything you need to plan smarter, fish better, and own every trip from first cast to last.