The Salmon 55 
ing upstream all the time. If the gravel is easy to work, the spawning- 
bed thus scooped out is often a foot deep ; and by the time spawning 
is completed the fish will have turned up the gravel to the extent of 
2 to 3 yards upstream, and about 2 feet across stream (Fig. 45). The 
spawning-beds can always be detected by observing the light colour 
of the gravel which has been newly exposed, contrasted against the 


Fic. 47.—Showing Salmon-Beds diverting the water where the gravel is raised, 
River Duart More, Sutherland. 
darker-coloured part on each side (Fig. 46). The whole process of 
depositing the spawn in the gravel to the depth of 10 or 12 inches occupies 
from three to fourteen days, according to the state of the weather and 
the water. So eager are fish to spawn in their own river that I have 
observed them begin five minutes after they entered. If, on the other 
hand, they are prevented from spawning by being delayed in pools 
during low water, they retain their spawn for weeks longer than they 
would have done had the water been suitable for their reaching the 
