XXXVl EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



from wbicli they originally started. Slipposing a locality in Ohio to 

 have been their first abode, there will be nothing to prevent the citizens 

 of all the States intervening between that place and the Gulf of Mexico 

 from arresting the upward returning run, and capturing a portion, if 

 not the entire body of the fish, so that little or no benefit would inure to 

 the parties through whose instrumentality this result was rendered 

 possible. 



As far as the United States is concerned, however, it is a matter of 

 no consequence who take the fish, since the great object is to increase 

 the supply of food to the nation at large, and every capture, whether in 

 Ohio or Louisiana, will tend to accomi^lish the same general result. 



After any species of fish has become permanently established in a 

 given body of water, their continuance therein will depend in great meas- 

 ure upon the enactment of suitable laws, securing their access to suitable 

 spawning-grounds, and protecting them during the critical period of their 

 existence, from capture or unnecessary destruction. Otherwise the 

 methods of artificial propagation must be resorted to indefinitely. The 

 various measures required for the protection of fish will be referred to 

 hereafter. 



17. — COMPARATIVE VALUE OP ANADEOMOUS AND OTHER FISHES. 



In reference to the freshwater fishes most worthy to attract the 

 attention of the General Government or of the States, the distinction 

 between resident species and those that are anadromous, or which spend 

 a part only of their life in the fresh waters and the remainder in the 

 ocean, must be clearly borne in mind. The species which belong exclu- 

 sively to fresh water, such as the brook-trout, the lake-trout, the land- 

 locked salmon, the white-fish, the black bass,* &c., are well worthy of 

 attention, and by judicious treatment can be introduced into new 

 waters, or their numbers greatly increased in any particular locality. 

 But, after all, there is a direct relationship between the number of any 

 kind of fish of a given weight and the amount of water needed to fur- 

 nish a supply sufficient to add definitely to that weight of food ; and 

 when the limit has been reached, we cannot, without feeding artificially, 

 advsmce upon the proportion. Where the waters are pure and con- 

 stantly renewed, and a suitable supply of healthful food is furnished 

 regularly, large numbers of fish may be kept and cultivated, where not 

 one in ten thousand would find an ample supply of natural food ; but, 

 as a general rule, the expense of feeding is such as to render the sale 

 at comparatively high prices necessary for a satisfactory result. 



It must be remembered, too, that however rapidly certain fish, espe- 

 cially the black bass, multiply in new waters, there is a limitation to 

 their increase, as shown by the experience of the Potomac Eiver. 



* All these species are able to live for a time in salt-water, and, indeed, if no obstacle 

 intervene, may run down to the sea for a time ; but by far the greater number belong to 

 tha interior waters of the country, and have no opportunity for such experiences. 



