28 BRITISH FRESHWATER FISHES 



and perseverance in making their way up stream, 

 leaping falls and swimming up rapids. 



During their ascent they often lie in large shoals 

 in certain pools, or they may rest behind big stones 

 which break the current. Opinions differ as to the 

 height which a Salmon can clear at a single spring, 

 but most authorities think lo feet about the limit, 

 and direct falls of more than this height are impass- 

 able. Fish have been known to make repeated vain 

 attempts to clear falls which are too high for them, 

 only giving up at last through sheer exhaustion. It 

 is from this habit that the Salmon takes its name, 

 the Latin Sahno being from the same root as salire, 

 to leap. 



It is only in the larger rivers that there are 

 regular runs of clean Salmon in the winter and early 

 spring, and it seems that in some of the Scottish 

 rivers, provided that the temperature be not too low 

 or the obstacles to be overcome impassable at this 

 season, a good proportion of these fish ascend fairly 

 rapidly right up to the head waters, where they stay 

 without actively feeding until the following autumn, 

 when they spawn there. In Ireland it has been 

 ascertained on the Blackwater that some of the 

 winter clean Salmon make only a temporary stay, 

 and in the spring drop back and resume active 

 feeding in the sea, to reascend later in the season. 

 This probably happens elsewhere in the case of 

 many of the fish which run up early in the year, 

 but as a general rule it may be stated that once 

 a Salmon has entered fresh water he usually stays 

 there until he has spawned. The summer fish run 

 up more quickly than the spring ones ; they are not 

 kept in the lower reaches by cold floods, the water 



