CRUSTACEA AS FOOD FOR YOUNG FISH. 29 



It does not necessarily follow from the previously mentioned ex- 

 periments, observations, and figures that crustaceans can be inex- 

 pensively raised in sufficient quantities to eliminate the necessity of 

 other kinds of food at times. But whether or not any of the forms 

 can be economically raised in sufficient quantities to exclusively af- 

 ford a constant perennial diet for a large number of young fish in 

 hatcheries, it would seem quite practicable to supplement other 

 kinds of food with crustaceans, at a very moderate cost, or even to 

 make crustaceans a temporary almost exclusive diet. Furthermore, 

 it would seem that natural streams and ponds might have the fish- 

 food supply increased by means of artificial stocking or trans- 

 planting. 



At present some method of pond culture would seem most feasible 

 for raising Crustacea. Shira ' stated that at the Fairport ponds, 

 which are fed by the Mississippi River water, in the spring ancl early 

 summer there is always an influx of Entomostraca, affording for the 

 time ample food supply, but that it is quickly and considerably re- 

 chiced by the young fishes in tlie ponds. He therefore recommended 

 some accessory ponds for the breeding of Crustacea. In such ponds 

 all the conditions and requirements having been considered, suitable 

 Avater plants should be placed, then the initial stock of crustaceans 

 secured. In some localities it is doubtless possible to obtain the 

 plants and crustaceans at the same time from the same source. It 

 has been seen that some forms of crustaceans are adapted to quiet 

 and warm waters, others to cold ponds or the cold depths of lakes 

 and to cold spring brooks, while still others seem capable of existing 

 within a wide range of conditions. On the other hand, some waters 

 may lack some essential element to support crustaceans at all. 



These are a few of the points which must be considered, whether 

 it is proposed to raise crustaceans for hatchery food supply or for 

 stocking natural waters. It goes without saying that the most com- 

 mon and most widely distributed species are the forms most easily 

 transported and adapted to the widest range of conditions and uses. 



^ Unpublished manuscript, 1918. 



