NOTES ON THE PROPAGATION AND DISTRIBUTION 

 OF POND FISHES. 



By G. W. N. Brown. 



"" The U. S. Fislieries Station, Orangeburg, S. C. 



From observation and study of the spawning habits of 

 pond fishes it is learned that the proper manipulation of the 

 water supply is a factor in incubation that should not be 

 overlooked. Especially is this true in regard to the incuba- 

 tion of black bass eggs. Black bass begin nest building and 

 spawning during the first warm weather of the season, 

 which occurs, usually, about the middle of February. They 

 seek the shallow portions of the pond as the warmth of the 

 sun has there penetrated to the bottom. As is well known 

 the male fish remains with the nest after the spawning is 

 concluded. His purpose in this is not only to protect the 

 eggs from enemies, but also, to keep the water constantly 

 changing on them so that they may obtain the proper 

 amount of oxygen which is necessary to incubation as to the 

 life of the fry after hatching. He accomplishes this func- 

 tion by passing back and forth over the nest with a gentle 

 undulating motion of the fins. By this means he also pre- 

 vents sediment from collecting on and smothering the eggs. 



Should anything occur to drive the male from the nest for 

 any considerable length of time the eggs, thus deprived of 

 his parental care, soon die. As the warm periods are 

 invariably followed by cold snaps which chill the surface 

 water it is necessary to close the supply valves to prevent the 

 cold surface water from the reservoir from displacing the 

 warm water at the nests and driving the male fish to seek a 

 more equable temperature in the deeper section of the pond. 

 For this reason the supply valves are closed at the Orange- 

 burg station until all danger of cold snaps has passed, some- 

 times remaining closed for four or five weeks. 



A former custom of bunching the brood fish in a few 

 ponds for the winter and distributing them to the various 

 spawning ponds early in February has been abandoned. It 

 was found that better results can be obtained by placing 

 them in the fall, after the ponds are drawn and cleaned, in 

 the ponds in which they will remain during the spawning 

 season, as it obviates the necessity of handling them after 



184 



