TROUT WATERS AND CARP WATERS 



The carp is found where the Loire flows through the 

 plain 'and generally at a low altitude; trout where the 

 Loire flows through the mountains and in high alti- 

 tudes : this is the regular state of affairs, of which we 

 are given a complete example. 



These differences are well marked, at least as far as 

 extremes are concerned. At the zones of junction, 

 over areas varying according to locality and time of 

 year, the species mingle, some decreasing and others 

 increasing. The connection is altered only gradually. 

 But when once these zones have been passed in either 

 direction, the distinction becomes clearer and more 

 obvious, and the two habitats, the two categories, are 

 quite definitely marked. Fishermen go to the mountain 

 waters for trout; and for barbel, bream, roach, and 

 bleak to the plain waters, or to lakes at a comparatively 

 low altitude. 



The contrast is so closely related to that of climate 

 in the areas themselves that we are inclined to think 

 one depends upon the other. Temperature, it 

 would appear, has a preponderating, if not exclusive, 

 influence; the trout preferring the cold mountain 

 torrents,, and the carp the warmer waters of the calm 

 and tranquil river. Now this is true only up to a certain 

 point. The coastal streams of Brittany and Normandy, 

 though they are at no great altitude, have trout in 

 them just as the mountain streams. Indeed, some 

 of them, despite the fact that their waters are very 

 warm during the summer, are considered the best 

 stocked of all, and are most visited by fishermen. 

 There must be another reason, and it is not far to 

 seek if we take into consideration the nature of these 

 waters which the trout frequent. They are always 

 fresh, swift, and continually renewed, practically always 

 clear and limpid. The influence of temperature plays 

 a part, but the principal factor is respiration, and this 

 is affected by changes in temperature, advantageously 

 or otherwise, as the case may be. 

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