254 FLY FISHING AND SPINNING 



decrease, and little or no food is taken by them. Their 

 bodies do not increase in size to any considerable extent, 

 and nature is therefore not called upon to make any very 

 great increase in the size of the scales. 



I cannot agree that the diminution of the annular 

 markings can be considered as being due as has been 

 suggested to disturbance of the salmon while on their 

 feeding ground. It is far too regular in its occurrence and 

 covers too long a period of each annual series. 



TROUT AND THEIR SCALES 



Trout will also develop their scales but more slowly 

 than the smolt as they encounter or pass into waters 

 containing (either as an element or a component part of 

 its smaller inhabitants) an increasing quantity of lime salts. 

 In the waters of New Zealand this exo-skeleton growth is 

 very remarkable, the Brown Trout of the Southern Island 

 especially developing similar scale markings to those on the 

 scales of salmon. The large trout in that country, save 

 during the spawning season, appear to reside and flourish 

 best in the tidal waters of the rivers, but the exact extent 

 of their visit to the sea, if any, has not yet been determined. 



Trout of one year or two years' growth, on leaving the 

 streams flowing into Loch Leven and entering its waters, 

 develop their scales, which, like the smolt scales, gradually 

 conceal their former markings (see Plate XXIX.). 



When young the skin of the ordinary brown trout appears 

 to the touch, and when scraped, to be as free from scales as 

 the lamprey. In many of our chalk streams, especially 

 in rivers like the lower part of the Test, where sub-aqueous 

 foods of the water-shrimp variety are plentiful, the scales, 

 as they grow, change very considerably the colouring and 

 appearance of the trout from that by which it is known in 

 the upper portions of its rivers. The scales can be detached 



