not always been attained, as shovm by Ball (19li9) , who increased the 

 abundance of plankton and botto.-n fauna without significantly affecting 

 the fish yield. 



Implications which may be drawn from piscicultural literature 

 resolve the subject of pond fertilization into two components: 



1. Cultural aspect. A culturist need only have the fertilizers, ponds, 

 fish and the objective of fish production. Fertilizers are appHed 

 in advised amoimts according to recommended procedure. Results will 

 vary^ but by altering the type and quantity of fertilizers the 

 culturist will arrive at increased yields of some consistency within 

 a few years. Ii/hen the increased production overbalances the cost of 

 fertilizers and fertilization, success is achieved. Knowledge of 

 pond metabolism is not essential, nor is it useless. An understand- 

 ing of the causes and effects of changes due to nutrient addition 

 will enable the culturist to produce more fish at less expense and 

 with greater consistency. 



2, Experimental aspect. This is explained and related to the above by 

 Meehean (l939,pJ.) . Referring to the cult^urist's view of scientific 

 investigation, he stated, "They (culturists) are not conscious of 

 the fact that results frnm such a study are dependent upon the 

 vagaries of nature and not produced at will as a series of chemical 

 experiments might be. It has not been realized that many problems 

 such as the social reactions of the fish, how they feed, how the 

 food organisms are produced, what food chain from the organic com- 

 pounds to fish is the most beneficial, what fertilizer will best 

 stimulate this food chain, must first be solved in order to know what 

 is happeningt. In other words, one must get to the fundamentals of 

 the reactions of the fishes and their relation to food in order to 

 offer an intelli{-;ent solution to the nroblem. We are still a long 

 way from that final solution." Other problems more intimate to nu- 

 tritional enrichment, might be added to Meehean' s list. The solu- 

 tions have not yet been compounded and remain to be reached only 

 throutih careful experimentation. Therein lies the need for experi- 

 mental fertilization. 



Piscicultural trends in the United States are directed toward sport- 

 fish production and, since protein food is abundant, no serious efforts 

 have been made to produce food fish. The phenomenal annual jrields of 1 to 

 2 tons per acre found in European and Asiatic carp c ulture cannot be ex- 

 pected under our cultural methods. The ecology and food ha'its of our 

 sport fish, together with the cost of f ertilizatlon, limit the extent to 

 which this method of production gain applies. Rounsefell and Everhart 

 (1953), considerint, the use of commercial fertilizers, estimated the cost 

 of fertilizing shallow oonds at l5 to 20 dollars per acre per year. At 

 that rate, without complete assurance of satisfactory results, artificial 

 enrichment may not be profitable. Present needs seem to call for the de- 

 velopment and standardization of fertilization methods in pond culture, 

 rather than the promotion of fertilization as now practiced. 



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