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species has come to choose for its spawning grounds the places that are most 

 suitable for its young to hatch and live in. These situations are likely to be 

 supplied with the natural food that the young require. As the fish grow they 

 will gradually work their way into the deeper and wider waters inhabited by the 

 adults. 



While we have only a meagre knowledge of the food of fish at the earliest 

 period of their lives, we know in a very general way what the adults of the 

 commoner species feed upon. It is of particular importance, therefore, when 

 iUtroducing any species into waters where it has not occurred previously, to 

 ascertain whether a suitable supply of its natural food is available. The flood 

 requirements of various species are stated in the pages that follow. 



Fry Tersus Fingerlings. 



Opinions differ as to the superiority of fry or fingerlings for stocking pur- 

 poses. The expense of rearing fish to fingerling size, and of transporting them 

 at that age, is very considerable. In many hatcheries space is not available for 

 keeping fingerlings, and it is therefore necessary to distribute a large proportion 

 of the annual product before the fish have advanced beyond the fry stage. A 

 very much greater number of fry than of fingerling can be supplied for a 

 given stream. Furthermore, the important instinct of ^elf-preservation is undoubt- 

 edly developed better and sooner in fish than are planted at the earlier 

 age. For these reasons many persons consider that the advantages of fry planting 

 outweigh its disadvantages. They believe that more fish will grow to maturity 

 from several thousand fry than from a few hundred fingerlings. The hatcheries 

 of all of the different states and the United States distribute fry, and their 

 experience has demonstrated beyond question that fry planting can be made 

 very effective. The prejudice against fry planting can usually be traced to 

 improper planting methods, or to unsuitable streams. It should not be for- 

 gotten that nature herself plants fry exclusively. 



Mountain Trout Stream in Winter 



(15) 



