Salmon and Trout Recognition

Salmon and Sea Trout Recognition

The difference between salmon and sea trout

Salmon (I) can be distinguished from large sea trout (II) by a more streamlined shape, concave tail, slimmer tail wrist, upper jaw reaching no further than rear of the eye, few if any black spots below lateral line, 10-15 (usually 11-13) scales counted obliquely forward from adipose fin to lateral line – trout have 13-16.


Salmon Sea Trout
General appearance Slender and streamlined More round and thickset
Head Pointed More Round
Position of the Eye Maxilla (bony plate usually alongside mouth) does not extend beyond rear rear of eye Maxilla extends beyond eye
Colour Relatively few spots Often heavily spotted
Scale count (number from adipose fin to lateral line) 10-13 13-16
Fork of tail Usually forked Usually square or convex
Wrist of tail Slender Broader
Handling Easy to pick up by tail Tail slips through hand

The differences between salmon parr, salmon smolts and young trout

Salmon and sea trout - Parr recognition

Salmon parr (I) can normally be distinguished from young brown/sea trout (II) by the more streamlined shape, deeply forked tail, longer pectoral fin, lack of orange on adipose fin, smaller mouth, sharper snout, only 1-4 spots on gill cover (often one large spot), well defined parr marks.


Salmon smolts

Salmon Smolts
When the salmon parr begin to migrate to the sea, usually in March, April and May, they gradually become more elongated and the fins darken. A layer of guanine crystals is laid down in the skin. rendering the body more silvery in colour and obscuring the spots and finger-marks, except on the gill-covers. They then become Smolts.