722 BULLETIN OF THE BUREAU OF FISHERIES. 



determination can not be made, of course, owing to the various factors of 

 quality and temperature of water, abundance of vegetation and of natural 

 food, etc., but reports from the several localities are of interest. 



At San Marcos, Tex.,' the best results are obtained with 24 to 30 large- 

 mouth bass to the half acre; of the smaller fishes — bream, rock bass, crappie — 

 60 to the half acre. 



A i-acre pond at Mammoth Spring, Ark., supports 100 small-mouth black 

 bass, and an average of 2,000 fry to each productive nest has been obtained, 

 the maximum number from one nest being 5,200. 



At Cold Springs, Ga., 100 adult large-mouth black bass in a pond of three- 

 fifths of an acre in area proved too many, and the number had to be reduced 

 to 60 or 70 for satisfactory results. In general, 50 to 75 brood bass to three- 

 fourths of an acre to an acre have been found the best number at this station. 

 Of catfish (Ameiurus nebulosus marmoratus), 100 to the acre have been found 

 satisfactory. 



Ponds at Wytheville, Va., accommodate 75- pairs of large-mouth black 

 bass to the acre with good results; of rock bass, 300 fish to the acre. 



At Northville, Mich., in a pond three-fifths of an acre in area it has been 

 observed that most satisfactory results were obtained with small-mouth bass 

 to the number of 29 females and 23 males, allowance being made for the occa- 

 sional polygamous tendency of the male. 



At White Sulphur Springs, W. Va., 36 pairs of small-mouth black bass is 

 considered the number for a i-acre pond. 



The maintenance of an abnormally large number of brood fish to a given 

 area results in more or less loss accor4ing to species, the mortality among the 

 brood fish of the small-mouth black bass being greater than with the large-mouth 

 bass and other pond fishes. The replenishing of the stock is most advanta- 

 geously accomplished by securing wild fish, preferably in the spring of the 

 year, and they may be advantageously transferred up to within two or three 

 weeks of the spawning season. 



COLLECTING THE YOUNG FISH. 



It is often desirable to remove the surplus fry from a pond before they have 

 left their nests, and there is now in use for this purpose a combination fry trap 

 and retainer which is placed over the nests, taking advantage of the fact that 

 the fry rise vertically .° This trap has proved of practical value in fish-cultural 

 ponds for small-mouth bass, and, where the nest area was not too great, for 

 large-mouth also. It has been used likewise in collecting small-mouth bass 

 fry from natural lakes, and is believed to be applicable to fry of other nest- 

 building fishes than the basses. 



o See Fuller, op. cit. 



