IMPROVEMENT OF FISHING THROUGH A 



KNOWLEDGE OF THE BREEDING 



HABITS OF FISHES 



By Prof. Jacob Reighard, University of Michigan. 



When the breeding season approaches most fishes leave 

 their usual haunts and travel a longer or shorter dis- 

 tance to their breeding grounds. The distance travelled 

 may be a few rods, as in the common sunfish, or it may 

 be hundreds of miles, as in the salmon. In any case it 

 brings the fish into new surroundings. Here it seeks 

 certain definite conditions which vary with the species. 

 Some of the fish require swift water, others quiet water ; 

 some seek a bottom of sand or gravel free from vegeta- 

 tion; others seek a bottom on which there is vegetation, 

 so that they may attach their eggs to its rootlets (which 

 they expose in making their nests) or hang them in 

 masses from its branches. Each chooses a breeding 

 ground suited to it. Compared to the total area fre- 

 quented by the fish of any water, the breeding grounds 

 are of limited extent. It results that the fish are crowded 

 together on the breeding grounds as well as in their ap- 

 proach to the grounds. This, in many cases, affords un- 

 usual opportunity for their capture. The whitefish is a 

 notable instance of this. 



The sexes are brought together on the breeding 

 grounds. At the instant when the eggs are laid there is, 

 in all known cases, intimate contact of the body of the 

 female with the bodies of one or more males in such a 

 way that the vents of the two sexes are brought together. 

 When the eggs are expelled the water is at the same 

 instant filled with a cloud of milt. Every egg is at once 

 surrounded by hundreds, thousands, perhaps millions of 

 sperms, each seeking to penetrate it. Under such cir- 

 cumstances fertilization is practically certain. It is a 

 popular error, from which fish culturists are not alto- 

 gether free, that a large percentage of eggs remain un- 

 fertilized in nature and that these consequently die. It is 

 commonly held that by resorting to artificial fertilization 



