380 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Government should take special measures for furthering this kind of 

 fish-culture. 



As regards fish-culture proper, artificial fish-culture, which consists 

 in the production of young fish in special establishments and the plac- 

 ing of these young fish in open waters, the opinion has now very gen- 

 erally gained ground in Europe that it is entirely useless to apply this 

 kind of fish-culture to those kinds of fish which spawn in spring and 

 summer. They are endowed with such a powerful faculty of propaga- 

 tion, and their impregnated roe develops in so short a time, that wher- 

 ever the necessary conditions for their well-being exist, sufficient young 

 fry is produced by nature's own activity, in a much safer way than man 

 can do it, if only care is taken that there is a sufficient number of 

 mature spawners and milters and suitable spawning places. One of 

 the most competent authors on this subject, Mr. H. Haack, director of 

 the German piscicultural establishment at Hiiningen, says in his official 

 Reports on the Berlin International Fishery Exposition of 1880, page 34: 

 "I have, for twenty years, made exhaustive experiments in artificially 

 raising most of those fish which spawn in summer, and in most cases I 

 have succeeded in raising a few thousand young fish of these kinds; 

 but I have nevertheless arrived at the conviction that all efforts made 

 in this direction have been mistakes, for even in the smallest open 

 spawning-ponds a hundred times more favorable results were obtained 

 than by the most careful artificial culture." 



The quantity of fish in any body of water is always in direct propor- 

 tion to the quantity of suitable food for the fish in their various stages 

 of development; but this quantity of food, though different in the dif- 

 ferent waters, is always strictly limited by nature; and it is not often 

 in the power of man to change this proportion for the better. It is, 

 therefore, impossible to make any water produce a larger quantity of 

 fish by the artificial hatching of young fish than the quantity of food 

 which it is able to produce entitles it to, no matter how large the body 

 of water. It is by no means the number and size of the various bodies 

 of water in a country which determine the quantity of fish in that 

 country, but the quantity of suitable food wdiich is produced in its 

 waters. 



As will be seen from the above review of the present condition of 

 artificial lish-culture, it is only those fish which spawn in winter, the 

 salmon and other salmonoids, as well as some fish of the Coregonus 

 family, which both in Europe and America have formed and still form the 

 principal objects of cultivation in special esta blishinents. Although 

 t lie cultivation of these kinds of fish in Europe has been carried on for 

 thirty veins, in some countries even on a very large scale, we have no 

 positive proof from any European state that this cultivation has, to 

 any noticeable degree, increased the quantity of fish in the open waters, 

 with the exception of a few trout-brooks, or that it has brought finau- 



