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

Brown and sea trout are the same species (Salmo trutta). Sea trout are brown trout that migrate to sea. Some brown trout migrate to sea and some sea trout eggs develop into brown trout that remain in the river throughout their lives.

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 all trout in a river.

Because of their large size, female sea trout provide most of the trout eggs laid in a river

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.

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

Recent scientic studies highlight the importance of sea trout to brown trout stocks

Over the last 12 years it has become clear that a few large sea trout are critical in maintaining the number of trout in a river.

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

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

Chapter 1 of the 2004 symposium written by Harris and Milner is available online in Sea Trout: Biology, Conservation and Management

In 2015 a report to the 2nd International Sea Trout Symposium revealed that 85% of eggs in the Shimna river were contributed by larger sea trout that have spent at least one winter at sea. This is likely to be true of many other systems, and has obvious implications for management.

In 2016 our understanding of the importance of larger sea trout to trout stocks were increased by scientists from Exeter University, Queen Mary University and Game and Conservancy Wildlife Trust. They reported that a small number of large female sea trout are responsible for maintaining the stock of trout in a river. Their paper is available online: Goodwin et al. (2016) A small number of anadromous females drive reproduction in a brown trout (Salmo trutta) population in an English chalk stream. Freshwater Biology 61, 1075–1089.

What you can do to help conserve trout stocks ?

Please protect sea trout smolts

Some young trout of 1 to 3 years old and 5 to7 inches long change to a silver colour before migrating to the sea.

These small silver trout are called smolts. Smolts shoal together before migrating to sea, usually in late March / April. They are often caught by anglers and should be handled carefully and released. After all they may be parent of many of the brown trout you catch in the future

Please conserve adult sea trout

Follow this advice from the Ness District Salmon Fishery Board

"Help conserve sea trout stocks by showing restraint in the number and size of fish that you kill (i.e. don’t kill the bag limit just because you can!). We would recommend the release of all large sea trout over 3lbs as they are important brood stock for future generations"

My favourite conservation device: The waterproof camera

It was common practice for fishing clubs and associations to award annual prizes to the angler who caught the largest fish.

In order to recognize the contribution of conservation-minded anglers, one forward looking association now awards a waterproof camera to the angler who returns the most fish.

An extension of Catch and Release is Catch Snap and Release

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

Fly fishing for the elusive sea trout: Devon's Silver Tourist

A fly fishing guide can show you where, when and how to fish for sea trout

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Careful daylight preparation is essential before fishing for sea trout

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