Fly Fishing Devon: Instruction & Guiding on Dartmoor Rivers

  • The Upper Yealm Fishery receives a good run of sea trout

  • We encourage Catch and Conserve
    because sea trout make a major contribution to healthy stocks of brown trout in the river

Sea trout conservation

Sea trout are brown trout that migrate to sea. Brown and sea trout are the same species (Salmo trutta). Some brown trout migrate to sea and some sea trout eggs develop into brown trout that remain in the river throughout their lives.
Scientists have not yet worked out why some trout migrate to sea. It is possibly an interaction between genetic and environmental factors. Maybe a lack of food in the river triggers migration. We do know that the better sea trout rivers tend to be short acidic rivers with easy access to good spawning and nursery areas.

Most sea trout are female . They produce an average of 800 eggs per pound of their body weight. Clearly migratory trout make an important contribution to trout stocks. The heavier, older sea trout produce more and larger eggs, and should be released for the sake of conserving the stock of trout in a river.

The ‘First International Sea Trout Symposium’ in 2004 highlighted the following key points:

  • Sea trout are the sea-running form of brown trout
  • Sea trout and brown trout interbreed
  • The majority of sea trout are female
  • Unlike salmon, sea trout can return to spawn up to 10 times
  • Because of their large size, female sea trout provide most of the trout eggs laid in a river
  • Genetic studies show that larger, longer-lived sea trout produce young that are also likely to grow large;
  • ‘Finnock’ are sea trout in their first year after l eaving the river as smolts
  • Some finnock enter rivers in the summer/autumn, and some of these breed
  • Sea trout and brown trout should be managed jointly

Diagram shows the life cycle of sea trout.
From the Celtic Sea Trout Project

Some sea trout flies tied by a South Devon expert who specialised in sea trout fishing by night and by day


This fly was fished at night after treatment with floatant so that it fished in the surface and created a wake when retrieved

Peter Ross

Tups Indispensible

This fly was fished as a dry fly or nymph during the day. It went through several versions with increasing amounts of red / pink dubbing

My favourite conservation device: The waterproof camera

At the "2nd International Sea Trout Symposium" held in 2015 it was reported that a study on the Shimna river in Northern Ireland revealed that 85% of eggs in the river were contributed by larger sea trout that had spent at least one winter at sea.
This shows how important sea trout are for maintaining healthy trout stocks.