TROUT FLY-FISHING IN AMERICA 



which sources control the food and pigment supply and 

 directly affect the action of the nerves, glands and pigment 

 cells. As abnormal coloration in trout, irrespective of 

 the species, is the great exception and not the rule, it vi^ould 

 seem as if, when considering the subject of coloration, 

 such conditions might fairly be eliminated as having little 

 material bearing upon the general subject. 



The coloration of trout in the first instance, that is the 

 characteristic coloring of each species and sub-species, 

 depends upon the dominant pigment colors which are nat- 

 ural to them. Under certain fixed conditions each sepa- 

 rate and distinct species and sub-species of trout will de- 

 velop to all practical purposes the same general colora- 

 tion. While under the same conditions two different 

 species or sub-species will develop entirely different 

 coloration, and this is due to the quality and quantity of 

 the different pigment colors natural to each. 



Change the water conditions and the coloration will 

 change ; change the character of the food and the colora- 

 tion will change; change the character of the water bot- 

 tom or the degree and character of light and the coloration 

 will change. In other words, a marked change in any one 

 of the elements that produce and make effective the colora- 

 tion of trout will change that coloration. 



One of the most marked illustrations of how col- 

 oration changes is found in the so-called sea-run 

 species of trout, such as the Steelhead and the Brook 

 Trout. 



137 



