382 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



but 1 families, viz : 2 catfisnes, 1 suckers, 8 cyprinoids, and one mem- 

 ber of the codfish family. Eight of the 15 species belong to one family, 

 the Cyprinidce. Not a single species of spiny-rayed fish has ever been 

 found in any of the streams in or about the Hills and it is not probable 

 that any will be found there. Many of the streams in or near the Hills 

 would apparently furnish congenial homes for sunfishes, bass, and even 

 several of the different species of darters. That these are not there 

 must be due to the nature of the lower courses of the streams draining 

 the Hills, and that of the Cheyenne to which they are all tributary. 

 The Cheyenne is ordinarily a shallow stream whose waters are always 

 more or less alkaline and filled with solid matter in suspension from the 

 extremely easily eroded country through which it flows; and fishes 

 would not ascend such streams from choice. 



The lower courses of the streams flowing from the Hills are through 

 the same Cretaceous beds and partake of the same character. Only 

 those species with which the struggle has become most severe will be 

 driven to seek protection antl food in the muddy, alkaline streams, and 

 they alone would eventually find their way into purer, clearer waters 

 above. This, of course, means the soft-rayed, non-rapacious fishes, the 

 suckers and minnows and other mud-loving forms. 



The spiny-rayed species are aggressive, extending their attacks to all 

 weaker forms about them, while the soft-rayed species are defensive 

 and seek protection in retreat. A spiny-rayed fish has no occasion to 

 ascend into the muddy, alkaline, and uncongenial portions of these 

 streams; the only thing which would cause him to do so would be a 

 quest for food, but he finds it easier and more agreeable to get food of 

 sufficient quantity and quality where he is. 



Not so with the soft-rayed fish ; he must not only search for suitable 

 food but he must also see that his enemy, the spiny-rayed fish, does not 

 catch him. The attacks of his enemies were probably the first cause 

 impelling him to take refuge in the turbid water. Finding suitable and 

 sufficient food in this new environment, and total relief from t^ie perse- 

 cutions of his old enemies, he finds the struggle for existence easy, the 

 surroundings in time become bearable and perhaps agreeable, and he 

 moves about at will through all parts of the muddy stream and even 

 into the headwaters where, still finding an abundant food supply and 

 none of his old enemies, he is content to make his home. 



Before mining began in the Hills in 1875 and 187G, nearly every stream 

 possessed all the natural conditions necessary to make it an excellent 

 trout stream. The waters were clear and cold, not subject to contami- 

 nation from any source, and suitable food, such as insects and insect 

 larvte, and the smaller Crustacea and mollusca, was undoubtedly found 

 then, as now, in abundance. With the exception of a few streams 

 which are now ruined by mining operations, the creeks of this region 

 are yet excellent for trout. 



