190 U. S. BUREAU OF FISHERIES 



The use of onl}'' 25 adult bass per acre would be too low for a 

 spawning- pond since the number of fry would be much less than a 

 pond of this size should produce. On the basis of our experience we 

 would make the following tentative recommendations regarding the 

 number of adults to be used in stocking hatchery ponds : 



1. Spawning ponds that are operated primarily for the production 

 of fr}' should be stocked with about 75 (50 females and 25 males) 

 2-pound fish or 110 (75 females and 35 males) 1-pound fish per acre. 

 The adults in such heavily stocked ponds should be fed minnows at 

 frequent intervals throughout the summer and fall. 



2. Combination spawning and rearing ponds from which no fry 

 are to be removed should be stocked with 15 (10 females and 5 males) 

 2-pound fish or 25 (17 females and 8 males) 1-pound fish per acre. 

 Such a pond should be stocked with from 500 to 700 large shiners 

 per acre. 



NURSERY PONDS 



The use of nursery or rearing ponds in the propagation of bass is 

 believed to be advisable since the fry can be utilized to better ad- 

 vantage than by other methods. Where the young bass. are reared 

 in the same ponds with the adults there is bound to be some competi- 

 tion for food which may result in cannibalism. The whole tendency 

 in holding young and adults together throughout the summer is to 

 reduce the production of fingerlings. Some pond culturists remove 

 the adults to holding ponds after the spawning season, but we believe 

 it is preferable to remove the fry to nursery ponds and allow the 

 adults to remain where they spawned. The latter method provides 

 complete control over the number of fry allowed in the ponds so 

 that they can be stocked at any desired intensity. Furthermore, it 

 is possible to stock the ponds wnth young fish of the same age and size 

 which, obviously, will tend to reduce losses from cannibalism. 



An additional argument for the use of separate rearing ponds can 

 be found in the fact that knowing how intensely a pond is stocked 

 it is possible in many instances to predict quite accurately the number 

 of fingerlings which will be left in the fall. 



The use of nursery ponds seems justified by the results obtained in 

 pond D 7 from 1927 to 1929. During this period the pond was uti- 

 lized as a nursery pond and the average production for the three 

 seasons was at the rate of 8,527 fingerling bass per acre. Pond D 4, 

 which is but slightly smaller than D 7, was used as a combined rear- 

 ing and spawning pond and during the same period produced an 

 average of 5,475 fingerlings per acre. In 1926 when both adults and 

 fingerlings were held in I) 7 through the summer the production was 

 only 3,779 fingerlings per acre. 



At Fairport bass fry are transferred to nursery ponds early in June 

 when they reach a length of about one-half to three-fourths of an inch 

 (15-20 millimeters). They are trapped in the spawning ponds by 

 means of a Hesen fish trap (Hesen, 1929), and are then transferred 

 to the nursery ponds. Tlie number of fry is ascertained by counting 

 several thousand and determining their weight. The bulk of the 

 fry are then weighed and the number calculated. This method is 

 undoubtedly subject to a certain amount of error, but it is the best 

 practical method we have at present. 



