SPAWNING OF BLACK BASS 35 



tingnish the male from the female, indeed 

 most fish-cultnrists say it is impossible to do 

 so, in spite of the contrary belief among fish- 

 ermen. Jnst before spawning time the females 

 are rounder in outline than the males. 



Barrenness occurs to a greater or less extent among 

 all fresh-water fishes, but this does not imply that a 

 female will be barren throughout her life. Some may 

 be barren one year and never again until there comes 

 what may be called a " change of life"; or barren for 

 two or even three successive years, and then produce 

 good eggs. Intermittent barrenness is more common 

 among introduced fishes in captivity than among wild 

 indigenous species. One of the most conspicuous ex- 

 amples in the eastern United States is the rainbow 

 trout, of which half of the females in a single pond 

 have been barren in one year, and at the same time 

 half of the males were either without milt, or yielded 

 infertile milt. This, however, is merely an illustration 

 of a well known law of nature, that changed environ- 

 ment is likely to produce sterility in animal life. 



Preference for Natural Nests. Many men 

 urge that artificial bass-nests should not be 

 placed nearer together than ten to fifteen feet; 

 and that the boxes ought to be so arranged that 

 the fish on one nest cannot see the fish on an- 



