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BULLETIN OF THE UNITED STATES FISH COMMISSION. 
nate the pelican. It would, indeed, be a lamentable result of my investigation if that 
dire calamity should befall the unwitting cause of this peculiar malady. One of the 
most charming minor effects of the singularly beautiful scenery of Yellowstone Lake to 
my mind is produced by the presence of these noble birds. I do not think such 
heroic measures are either called for or advisable. The trout of the lake can never 
figure as the food supiily of a large number of people. Their abundance or scarcity 
neither raises nor lowers the price exacted of tourists by the hotel association. They 
are destined to contribute more to sport than utility. A speedy remedy is therefore 
not necessary. 
With the increase in numbers of visitors to the lake will go greater destruction 
of trout by enthusiastic fishermen. This will probably reduce the number of diseased 
fish at a more rapid rate than it will that of the healthy ones, and if the precaution 
be taken not to leave dead fish on the shore, and not to throw them in the water, where 
in either case they would probably be eaten by the pelican, the chances of the latter’s 
becoming infested with the parasites will be correspondingly lessened. And particu- 
larly if the lake be stocked with some other species of fish (of which I think the chub 
of Heart Lake is most suitable, since it is an omnivorous feeder, and therefore not 
likely to interfere seriously with the food of the trout, while furnishing the latter 
with much-needed animal food, and at the same time lessening the chances of the 
trout’s being eaten by the pelican, and since the parasite does not develop in the chub) 
a lessened parasitism of the pelican would result ; and with fewer parasites in the 
pelican would go a diminution in the number of ova disseminated in the water, and 
consequently a lessening of parasitism in the trout. 
It is probable, also, that the presence in the lake of some fish which would form a 
part of the food of the trout would result in imparting a more vigorous constitution 
to the latter and make it better able to withstand the strain of excessive parasitism. 
At any rate, before a war of extermination is waged against the pelican it would 
be well to ascertain whether or not Dihothriuni cordiceps develops in other fish-eating 
birds. My own investigations have not been extensive enough to enable me to decide 
this question. Beside the pelican, the only birds of the lake that I had an opportunity 
to examine were three species of duck, none of them ijiscivorous, one hawk, one heron, 
and three gulls. In one of the latter I found a>Dibotlirium bearing some resemblance to 
the trout parasite, but evidently a distinct species. 
Washington and Jeffekson College, January 1, 1891. 
