1028 EEPORT OF COMMISSIONEE OF FISH AND FISHERIES. [20] 



is very apt to make a mistake iu the feeding, and instead of quickly 

 reaching the weights required for the new period, and thus finishing 

 the transition and perfecting the new period during the first year, this 

 result will be still more delayed than would have been the case if arti- 

 ficial feeding had not been employed. 



I will endeavor to illustrate this by an example from my own prac- 

 tice. Suppose a six years' period is to be changed to a four years' pe- 

 riod, with a final weight of 1,250 grams. For this purpose there would 

 be required for the sale-ponds, 12,700 fish — 1,300 weighing at least 600 

 grams each per hectare; for the growing-ponds, of Class II, 12,700 fish — 

 216 weighing at least 250 grams each per hectare; and for the growing- 

 ponds of Class I, 12,700 young fry, 325 per hectare. 



There are on hand from the preceding period : 



Young fry: Ko. offlsb. 



At 0.029 kilogram 18,760 



Fish: 



At 0.113 kilogram 845 



At 0.143 kilogram 1,721 



At 0.169 kilogram 2,031 



At 0.181 kilogram 2,121 



At 0.249 kilogram 2,252 



At 0.280 kilogram 2, 177 



At 0.341 kilogram 2,353 ' 



At 0. 467 kilogram 2, 859 



16, 259 



Fish : 



At 0.602 kilogram 1,683 



At 0.664 kilogram 1,900 



At 0.712 kilogram 2,712 



At 0.780 kilogram 2,722 



At 0.021 kilogram • 3,497 



12, .514 



(It should be. observed that, in this case, there were actually about 

 fifty different weights which, for the purpose of simplification, are here 

 already distributed in groups, the average weight of which has been 

 taken.) 



If the six years' period had been preceded by a systematic course of 

 pisciculture, the carp should, in this case, — where the weight of the 

 young fry, when placed in the growing-ponds, was about 30 grams, and 

 the final weight reached 1,280 grams, — have reached the following 

 weights during the intervening years: in the first year of growth 155 

 grams, in the second year 342,5 grams, in the third year 635 grams, and 

 in the fourth year 967.5 grams. I have to give these figures without 

 the detailed calculations on which they are based, as this would lead 

 us too far; but any one who has worked a six years' period will hardly 

 doubt their correctness, as his experience will teach him that they are 

 at least approximately correct, even if he should be inclined to smile at 

 the idea of calculating such things with mathematical accuracy. 



In supposing that in consistent and systematic pisciculture there are 

 variations in these weights, e. g., during the first year of growth from 

 120 to 200 grams, in the second from 300 to 400, in the third from 600 



