Sea Trout Recognition

The sea trout is in fact the same species as a brown trout salmo trutta. The sea trout is simply the migratory form. Like the salmon a brown trout can be anadromous. In English this means that it spawns in fresh water but migrates to the sea for feeding.

Not all brown trout become sea trout. In fact nobody is sure why some do and others don't. It may be partly genetic and partly environment driven. Certainly waters where feeding is relatively poor seem to produce more sea trout. Since mature trout are territorial it is thought that the weaker fish are forced downstream by the stronger ones. Eventually they reach the richer feeding in the sea and start to grow more quickly.

You might also come across bull trout. These never go to sea proper, but hang about the estuaries. Again they grow faster. Sea trout don't venture so far out to sea.

Whereas salmon will venture out to the Faroes and Greenland, the sea trout tend to hand around the coasts. This probably explains why sea trout are more susceptible to sea lice infestations from fish farms which are found around the coast.

Salmon can be distinguished from large sea trout by:

1. a more streamlined shape,

2. concave tail,

3. slimmer wrist,

4. upper jaw reaching no further than the rear of the eye,

5. few if any black spots below the lateral line,

6. 10 to 15 (usually 11- 13) scales counted obliquely forward from adipose fin to lateral line - trout have 13 - 16

A Sea Trout kelt of 14lb - note the huge spade tail and lots of spots below the lateral line.

A spring salmon of 20lb, note the concave tail, silver flanks and no spots below the lateral line. The belly is marked, but well healed.

The Atlantic Salmon Trust
7 Kirkmichael Road
Pitlochry
PH16 5JQ
Tel. 01796 473 439