144 



for them to leave the ocean, seek the fresh water and 

 complete their duties of procreation. No migratory tribe 

 of fishes can accomplish the round of its life duties in one 

 element ; it may live and grow m the sea, but cannot 

 breed there ; while although it must breed and may live 

 in the fresh water, it will not attain its full proportions 

 in that element alone. Instinct, which could hardly 

 teach tbem how many of their number to direct to any 

 given stream before they had explored it, could and does 

 inform them when the proper time of year has arrived 

 for them to deposit their eggs. The temperature of the 

 water and the heat of the sun are their guides, in exact 

 accordance with which will their appearance in the streams 

 take place, occurring first in the more southern and gradu- 

 ally succeeding in those to the north. -It cannot be doubt- 

 ed that a sensible diminution of the entire shad supply 

 of this continent has taken place within the last fifty years, 

 and were this drawn from one body it would be natural 

 to expect that while the rivers first reached by the. school 

 would be filled as they originally were, those last in order 

 would be left utterly bare. In such case the school com- 

 ing from the south would send off their full quota to the 

 streams of Florida, Greorgia, South and Xorth Carolina, 

 until the entire body was exhausted, and those of the 

 ^ew England or middle States were left with no fish 

 whatever. Such, however, is not the fact, and it is only 

 those streams where man takes more than his proper pro- 

 portion that are being gradually depopulated. 



When the mature shad prepare to perform the duty of 

 propogating their race they direct their energies to that, 

 and without intermission. They seem to be pressed by 

 an overpowering necessity, and will do their best to over- 

 come all obstacles that nature or art may have placed in 



