92 U. S. BUREAU OF FISHERIES. 



the recommendation of a friend or because the species has afforded 

 him pleasure in another region. The importance of making a careful 

 surAey of the waters to be stocked, with the view of determining the 

 species best adapted thereto, is often not recognized. It has been 

 jH-oved beyond a doubt that in nearly every case it is advisable to 

 plant a species which is native to the locality, and in specifying his 

 choice of fish the applicant should bear this in mind. Nonindigenous 

 species should not be introduced unless it can be clearly shown that 

 the native species, because of changed conditions, have failed to 

 maintain themselves. There are many notable examples of the suc- 

 cessful transplanting of fishes where the results have been highly 

 beneficial. However, there is always an element of uncertainty in 

 the ]:)lanting of nonindigenous fishes in any region, and it should be 

 undertaken only, after a careful consideration of all phases of the 

 situation, because if promiscuous plantings were to be permitted the 

 work of fish culture might easily become a curse instead of a blessing 

 to mankind. 



The carp is an appropriate example of the results of the indis- 

 criminate introduction of a foreign species. This fish was popular 

 in the early history of fish culture in America, largely, perhaps, 

 because it was a favorite with European fish-culturists and because 

 of its rapid growth and ready adaptability to new surroundings. 

 Through carelessness and indifference the carp became widely dis- 

 tributed in the waters of the country, with the result that in many 

 sections a stigma will always apply to this sturdy fish. Neverthe- 

 less, there is a place in the piscatorial world for the carp, and for 

 certain waters it fills a demand that can not be adequately met by 

 any other species. It frequently happens that carp can be success- 

 fully and profitably proj^agated in waters that are quite unsuited to 

 the finer species ; and, under proper restrictions, this idea should be 

 encouraged. 



Aside from possible injury to indigenous species that may follow 

 the introduction of foreign fishes, there ai'e other important points 

 to consider: Will the new inhabitants find a suitable temperature 

 range and other conditions congenial to their reproduction? Will 

 the food supply be of a suitable character and ample for their needs? 

 Unless these essentials are present an introduced species can not 

 establish itself in a new environment on a self-maintaining basis. 

 Not infrequently species of fishes that are possessed of the highest 

 food and game qualities in their natural habitat will, when trans- 

 planted in less favorable surroundings, degenerate to a point where 

 they have no attractions either from a food or a game standpoint. 

 Even the planting together of the same species of fish taken from 

 different sections of the country or from different streams in the 

 same section may be inadvisable. Certain investigators have ex- 

 pressed the belief that such plantings may lead, or in certain instances 

 may have already led, to a form of hybridization which may result 

 in seriously impairing the virility of the progeny. 



Many of the more progressive State fish and game commissions 

 have requested that all applications for certain species of nonindige- 

 nous or predacious fishes be submitted to them for approval. The 

 bureau commends this policy, and all such applications, including 

 those for carp, are referred before acceptance for the proper State 



