FISH-CUWURAL PRACTICES IN THE BUREAU OF FISHERIES. 72 1 



various design, but embody in general some sort of a container for the gravel 

 the fish require, together with a shield or screen on two or three sides." The 

 primary use of screens was for the purpose of shielding the fish from view of 

 passers-by, but the practice resulted in the discovery that the fish will accept 

 shielded nests at more frequent intervals than when visible to each other. It 

 is therefore of first importance that in the placing of nests the screens be arranged 

 to meet this condition. . 



When shielded artificial nests are not provided it is customary to deposit 

 here and there in the ponds mounds of coarse gravel, 18 inches to 2 feet in 

 diameter and about 6 inches in height, that the breeders may select and prepare 

 their nests with these. 



Large-mouth black bass, though they sometimes accept gravel mounds as 

 nests, naturally seek a weedy bottom, devoid of gravel. Peat-like sods or 

 similar substances put into the pond prove acceptable to this species as nesting 

 material. 



The superintendent of the Cold Springs, Ga., station endeavors to imitate 

 nature by providing "homes" for all adult fishes whether spawning or not. 

 For the large-mouth black bass and rock bass, boards 3 feet to 10 feet in length 

 are laid flat under the water so that by the natural contour of the bottom spaces 

 5 inches to 8 inches deep are formed under the boards. Catfish {Ameiurus nebu- 

 losus), which prefer to dig their own nests, are provided with boards either laid 

 flat on the pond bottom or where there will be under the center of the board a de- 

 pression an inch or two in depth. Where necessary, the boards are fastened by 

 stakes at both ends, but when placed along the bank, where conditions are favor- 

 able for such a course, one end of the board may be driven a short distance into 

 the embankment, while the other end is staked. After having been submerged 

 a month or so the boards will remain in place without fastening. With proper 

 precautions against projections these shelters do not materially interfere with 

 seining operations. 



For the crappie, roily water seems to be essential during the spawning 

 season. At stations where there are no naturally roily ponds it has sometimes 

 been found desirable to introduce a few carp, which roil the water in rooting 

 around the bottom of the pond and do not seem to disturb the crappie. 



NUMBER OF BROOD FISH. 



The desirability of maintaining a maximum number of brood fish to a given 

 pond area has led to a comparison of experience at the different stations in an 

 effort to arrive at some approximate average for a working basis. Conclusive 



oQne form of nest in use is the design of A. E. Fuller, described in his paper entitled "New and 

 improved devices for fish culturists," Proceedings Fourth International Fishery Congress, Bulletin 

 U. S. Bureau of Fisheries, vol. xxviii, 1908, p. 991-1000, pi. civ-cvi. 



