Brown Trout 191 
Loch Gorm trout (Fig. 166), for instance, nearly all have round 
black spots on their sides, and look almost like a different species. 
But these spots, as before, are the result of the special feeding in 
this loch. The feeding has also a great deal to do with the shape. 
The richer the feeding the smaller are the heads and the plumper 
the bodies. Then the nature of the soil and the colour of the water 
have much to do with the colour of a trout. Clear water and a 
light-coloured bottom produce silvery-coloured trout, while peat- 
CEES a 
CW A iS 
Iva: we — Jt. ~My 
2 i 

Catan 
Photo by Harry Anderson. 
Fic. 189.—8-lb. Loch Veyatie Trout. June 1906. 
coloured water produce dark-coloured trout. Young trout before they 
spawn are brighter in colour than older trout. Trout, however, which 
live in tidal water which is brackish are nevertheless silvery like sea- 
trout, and present a strong contrast to Loch Leven trout. A photo- 
graph of a trout from the tidal waters of the Tay is shown in Fig. 167. 
The trout in Loch Harry in the Orkney Islands also frequent brackish 
water, and it is difficult to tell from their appearance whether they are 
sea-trout or brown trout. 
Many trout are compelled to be migratory because the streams are 
so small, and when they grow to a certain size they have to fall back 
into the sea to protect themselves. They must either go into brackish 
