584 



SCIENCE 



[Vol. LV, No. 1431 



pleasure from angling them in every stream 

 and lake which they can conveniently approach. 

 And yet, it is no exaggeration to say that aside 

 from some limited flsh-hatching operations, we 

 have done practically nothing to intelligently 

 conserve these creatures for future generations. 



Although there are a good many sides to 

 the program of fish conservation, yet this 

 evening I wish to bring to your attention only 

 one phase of it, namely, fish-parasitism and 

 point out some of the biological problems with 

 which it is intimately linked up. 



During the last few years I have been devot- 

 ing a good deal of attention to fish-parasitism 

 in the Northwest and can say that this is a 

 field which has hardly been touched. There 

 are great numbers of fish parasites in this 

 region : bacteria, protozoa, cestodes, trema- 

 todes and Crustacea which are infecting the 

 fish and killing off great numbers of them. 

 These afford many fields of investigation which 

 are not only thoroughly scientific, but of great 

 practical value. We need good taxonomic keys 

 of these parasites, their life histories and their 

 effects on the various hosts. 



Furthermore, this knowledge should be sup- 

 plemented by a careful study of the conditions 

 within our lakes and streams which are con- 

 ducive to fish-parasitism. At present we are 

 working entirely in the dark, and as a result 

 of it much of our good time, effort and money 

 are wasted. I will cite but one instance along 

 this line to make my point clear. 



It is a common practice among our game 

 commissioners to stock a body of water with 

 fish and then to close it down for purposes of 

 allowing the fish to multiply, with the view of 

 obtaining a plentiful supply of spawn for 

 hatching operations. My observations along 

 this line have convinced me that this is an er- 

 roneous practice. In the first place, closing 

 down a stream makes for a rapid multiplication 

 of fish so that the available food supply soon 

 becomes inadequate to maintain all of them. 

 A fierce struggle for existence ensues in which 

 many of the weaker, but nevertheless desirable 

 fish are killed oft'. Even those that remain ap- 

 pear to be starred for lack of food. In the 

 second place, the congested conditions within 



the stream make possible a rapid spread of 

 any parasitic infection which happens to make 

 its appearance among the fish. And lastly, 

 when a stream is closed down for any length 

 of time its shores afford an ideal, undisturbed 

 habitat for many fish-destroying birds and 

 other animals. These not only kill off large 

 numbers of fish, but they may also be the 

 means of disseminating various parasitic or- 

 ganisms among them. 



It seems to me that before we can even talk 

 of cure and prevention, we must know the 

 parasitic organisms as well as the conditions 

 which make parasitism possible. But, with- 

 out these facts we are powerless to do any 

 good. What is greatly needed in this North- 

 west section is a number of biological sur- 

 veys for the purpose of studying and mapping 

 out the various ecological factors of the regions 

 in which fish or game are to be planted. We 

 ought to know a good deal about such factors 

 as available food supply, oxygen content, tem- 

 perature variations, predatory and parasitic 

 organisms, etc., of a place before any kinds 

 of animals or plants are introduced into it. 

 Knowing these conditions we can then intel- 

 ligently fit each organism into that particular 

 environment where it will thrive best. While 

 the initial expense involved in the establish- 

 ment of such surveys will be considerable, yet 

 the benefits derived in the long run will more 

 than repay us for our efforts. 



Nathan Fasten 

 Oregon Agricultural College 



THE THIRD ASIATIC EXPEDITION 



OF THE AMERICAN MUSEUM 



OF NATURAL HISTORY 



The Third Asiatic Expedition of the Amer- 

 ican Museum of Natural History, in coopera- 

 tion with the American Asiatic Society and Asia 

 Magazine, will leave Kalgan on the nineteenth 

 of April for the continuation of its work in 

 Mongolia. 



During the last six months field operations 

 have been conducted in various parts of China 

 which have been extraordinarily successful. All 

 the members of the expedition's staff have now 

 arrived in Peking and the final preparations 



