16 THE FRESH- WATER TROUT. 



Leven in Fifeshire, the Blackadder and the Leet in 

 Berwickshire, the lower parts of the Clyde in 

 Lanarkshire, and Biggar Water in Peehlesshire. All 

 these streams run very slowly ; in some of them 

 there are miles where it is difficult to tell at first 

 sight which way the water is flowing. They all 

 contain large, well-shaped, and in general red-fleshed 

 trout, owing to the superior feeding which such 

 streams, running over a bottom of mud or marl, 

 possess, and also to the circumstance that they are 

 generally not numerous. This last fact is due to a 

 number of causes. Deep, slow-running streams are 

 not favourable for spawning, trout requiring shallow 

 water for that purpose. They are also ill- provided 

 with stones and gravel, where the young fry may 

 shelter themselves from their rapacious relatives, 

 and from pike, which generally abound in such 

 places, and commit sad havoc. It is observed that 

 wherever these fresh-water tyrants are found, the 

 trout attain large size, those that escape getting 

 double the quantity of food they would under 

 ordinary circumstances. It seems as if the feeding 

 of a river could only support a certain weight of 

 trout, so that where they are very numerous they 

 are not large, and vice versa. Hence proprietors of 

 ponds sometimes drag them with a net, and take 

 out the small fish to improve the size of the re- 

 mainder. 



Of the opposite class from those just mentioned 

 are very rapid streams. Of this kind are most 



