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. Ratnsow Trout (Salmo shasta). 
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- 
et upon volume of water, temperature, food supply, ete. 
Tnder 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- 
