8 FISHES OF THE YELLOWSTONE NATIONAL PARK. 



embryo. This passes into the trout, where it becomes established 

 and assumes the form commonly observed. The fish is eaten by 

 the pelican, and in the intestinal tract of this bird the parasite attains 

 its adult and reproductive stage, and its round of life is there com- 

 pleted. The eggs pass from the bird into the water, and a new 

 generation is begun. 



This parasitism of the trout is of much concern to the angler 

 because the fish thus affected are likely to be lazy or inactive. To 

 the consumer such fish are more or less objectionable, not only 

 because they are " wormy," for the worm is a " tapeworm" of 

 proverbial aversion and dread, but because the fish are sometimes 

 deteriorated in quality and flavor and considered unfit to eat. To 

 the fish culturist, whose concern comprises both of the foregoing, 

 there is the fear of spreading the infection to other waters. As the 

 most seriously affected trout are found in the warmer waters, the 

 angler can get some relief by fishing in cool waters. 



As an answer to the query of the consumer, it may be said that no 

 known tapeworm for the adult of which man acts as host finds its 

 intermediate host in fishes. Furthermore, as cooking destroys the 

 vitality of the worm, there would be little or no danger from that 

 source, besides which there is probably no edible fish that is not 

 more or less affected with some kind of parasitic worms. 



However, it may dispel apprehension to state that similar tape- 

 worms in some places are actually eaten as food and considered 

 delicacies. In Italy a parasite of the European tench and other 

 cyprinid fishes is sold in the markets under the name of maccaroni 

 piatti and eaten, usually under the mistaken notion that it is the 

 roe of the fish. The same or a similar parasite is also eaten by 

 many persons in Lyon where it goes by the appropriate and truthful 

 name of ver Nanc (white worm). It is stated on good authority 

 that in this country a choice portion of another fish not infrequently 

 contains encysted parasitic worms which the consumer, not knowing 

 its nature, selects as a delicate morsel. However, since these facts 

 are not likely to completely remove a deep-seated prejudice or lead 

 to a general demand for tapeworms on the menu of the park hotels, 

 it would be desirable to be rid of these parasites or even to reduce 

 the number. 



Several methods, more or less feasible, have been suggested. 

 The most practical and at the same time the most desirable of these 

 is the introduction of other fishes into Yellowstone waters to detract 

 the attention of the native trout from itself as a food; for it is not 

 improbable that the intensity of this parasitic infection of the Yellow- 

 stone Lake trout is increased by cannibalism, since there are no other 

 fishes for the large trout to eat. Also, these additional fishes not 

 being subject to infection by this trout-pelican parasite, by affording 



