142 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
irrigating ditches and are left to perish in the fields. The destruction of trout by 
this agency is far greater than that due to all others combined, and itis going on in. 
almost every irrigating ditch in Colorado. 
The fishes of Colorado comprise very few species, only 52 indigenous 
species being enumerated by Dr. Jordan, of which 2 were new to science, 
The Rocky Mountain trout, Salmo mykiss, is found in all the moun- 
tain lakes and streams tributary to the four main rivers, extending 
down to a point where the summer temperature reaches 60° to 65° F., 
where it gradually disappears. The mountain minnows, Rhinichthys 
dulcis on the eastern slope and Agosia yarrow? in the Colorado basin, 
accompany the trout in the mountain meadows, not, however, ascending 
so near to the sources of the streams, but, on the other hand, much 
farther down their courses. They are eaten by the trout. The blob 
or miller’s thumb is very abundant in the clear and cold waters of the 
Colorado basin, and is very destructive to the eggs of trout. The 
suckers extend up the rivers more or less to the point where the trout 
disappear, and, for the most part, the species are different in the difter- 
ent basins. The species of Catostomus and NXyrauchen reach a consid- 
erable size, but are of poor quality for food. The suckers and the 
chubs, especially the latter, are very destructive to the trout eggs. 
The Ptychocheilus lucius of the Colorado attains a great size, and in 
default of better fish assumes economic importance. The bulk of the 
rich fauna of the Mississippi, as well as most of the Texan fishes, are 
excluded from Colorado on account of the intervening turbid waters 
through which they can not ascend. 
Three species of the Salmonide have been introduced into some of the 
streams and lakes of Colorado, the Eastern brook trout most exten- 
sively, the rainbow trout of California, and the landlocked salmon of 
Maine. Carp ponds have also been established in the State, and Dr. 
Jordan strongly recommends the introduction of the larger catfishes 
into the tributaries of the lower Colorado, the entire basin of that river 
having, besides the trout, only fishes of very inferior quality for food. 
Tributary to the Arkansas River are the Evergreen Lakes, a series 
of trout ponds, wholly or partly artificial, fed by cold streams from the 
flanks of Mount Massive. One of these streams, having its rise in the 
largest permanent snow field in Colorado, has been chosen as the site 
of the new U.S. Fish Commission hatchery. Dr. Jordan states that no 
better location for that purpose could be desired. 
In Utah no permanent streams of any importance, except the Colo- 
rado River, occur to the east of the Wahsatch Mountains. West of the 
divide of those mountains lies the Great Basin, in which the Salt Lake 
Basin and the Sevier River were examined. In the former 14 species 
of fish, including the trout, Salmo mykiss, were taken, and in the latter 
7 species. The trout of Utah Lake are of excellent quality and reach 
a weight of 3 to 10 pounds. The same trout also oceurs in Panquitch 
