FISHES OF THE YELLOWSTONE NATIONAL PARK. 21 



sightly trout, the condition of which is commonly attributed to para- 

 sitism, are often fish which are run down from breeding, although they 

 may carry some parasites. There is scarcely a fish that swims that 

 is not more or less infected by some sort of parasitic worm, and in 

 this respect the Yellowstone fish do not appear to be worse than fish 

 of many other lakes in the country. 



It has been said that there are two varieties of native trout in the 

 park, the larger ones of the Yellowstone, with bright yellow bellies, 

 and the smaller kind more silvery in appearance and exhibiting much 

 greater activity and game qualities, of which Tower Creek fish are 

 examples. Also trout of Yellowstone Lake seem to differ from those 

 of Heart and Henry Lakes in having more distinct and rather less 

 numerous black spots. However, in this respect very much indi- 

 vidual variation is shown. 



This is the principal fish artificially propagated by the United 

 States Bureau of Fisheries at the hatcheries on Yellowstone Lake and 

 Soda Butte Creek. From three to twenty million eggs are taken 

 annually. After the local park waters are liberally stocked the re- 

 maining young are supplied to suitable waters in the adjoining 

 States. The park, however, should and does have the first and 

 major claim on the hatchery output. 



4. RAINBOW TROUT (Salm,o sJiasta). 



The rainbow trout has its geographical range in the mountain 

 streams of the Coast Range and the western slopes of the Sierra 

 Nevada Mountains, but the natural abode of the rainbow trout of 

 fish-cultural fame is the McCloud River, Calif. This form, now 

 recognized as a species distinct from Salmo irideus, bears the name 

 of Salmo shasta. It has been successfully introduced into many 

 streams in different parts of the United States where it was not 

 previously found. 



The rainbow, first introduced into the park in the Gibbon River 

 in 1880 and subsequently planted in various waters and on numerous 

 occasions, has become one of the most abundant, most widely dis- 

 tributed, and most popular of the park fishes. The waters stocked, 

 in addition to the Gibbon River above and below the falls, have 

 included the Gardiner River, tributaries of Yellowstone Lake, and 

 various small lakes. 



The size attained by the rainbow trout varies greatly and is de- 

 pendent upon volume of water, temperature, food supply, etc. 

 Under certain conditions it reaches an extraordinary size, but in 

 the ordinary environment 6-pound or 8-pound fish are to be regarded 

 as large. In general, it may be said that the fish does not overrun 

 2 pounds. Its food is composed largely of insects. 



This fish now abounds in the Gibbon River both above and below 

 Virginia Cascades, and good fishing is found at times at the junction 

 with the Madison. Regarding this stream the park superintendent's 

 report for 1897 shows that the fish planted above the cascades seemed 

 to have come down over the falls, as but few were found above, while 

 below the stream was well stocked to its junction with the Firehole. 

 In the Gibbon River above the falls it appears that the supply has 

 been greatly depleted, in fact, nearly fished out, owing to the cir- 



