188 



U. S. BUREAU OF FISHERIES 



was 7.25 acres. This gives an average production of 6.39T fingerlings 

 l^er acre. 



That with the proper care good results may be expected each 

 year is shown by the production in pond D 7 from 1927 to 1929. 

 During this period this pond was used as a nursery pond for the 

 largemouth bass. It was fertilized and stocked with minnows to 

 supply forage for the bass. The average annual production for the 

 3 years was 8,527 three-inch fingerlings per acre. 



BROOD STOCK 



When the present investigation was begun, it was the common 

 practice at Fairport, as at other stations, to depend on wild fish 

 for brood stock. These fish were taken from the Mississippi River 

 from time to time as required. This practice has been given up, 



FiuuKE 4. — Seining fingerliug bass from the ponds at Fairport 



and all the fish needed to replenish the brood stocks are now being 

 reared in the station ponds. Each year there are a number of excep- 

 tionally large fingerlings ranging from 5 to 8 inches in lengtli. 

 These fish are reared to maturity and kept for breeding purposes. 

 That it is possible to rear brood stock is shown by the lact that at 

 present most of the brood fish used in experimental work have been 

 reared in the station ponds. A number of 2 and 3 year old fish have 

 also been shipped to other localities. The only fish that have not 

 been reared at the station is a lot of 24 adults which were originally 

 wild fish and were at the station when these investigations were first 

 started. The age of these fish is not known, but they have improved 

 each year and last season produced an average of over 6,500 fry to 

 each female. 



As a result of rearing our own brood fish, we know definitely the 

 age of each fish and may also practice some selection so that only 

 su]ierior fish are retained for breeding })urposes. Another advantage 

 is that it is possible to determine definitely the age at which the bass 



