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February, and is succeeded by other schools which enter 

 the streams further north, as the season advances and the 

 temperature of the water increases. It was for a Jong 

 time supposed that immense shoals of herring, shad and 

 other migratory fishes traversed the ocean in certain 

 circuits, sending off divisions at all convenient spots, the 

 main body keeping on its course, and these smaller armies 

 filling #nd utilizing for spawning purposes the various 

 rivers adapted to their wants, no more being sent to each 

 than would be necessary. These voyages were even 

 thought to extend across the oeean and possibly even 

 around the entire globe, and it was supposed that the 

 shad and herring which visited Europe were a portion of 

 the same vast body which skirted the coast of the United 

 States of America. Investigation has tended to break 

 down this theory, and it is now generally abandoned. 

 It was found that over fishing in certain streams diminish- 

 ed the yield of such streams without affecting others that 

 were better preserved or more neglected. This would 

 not have been the case if the supply carne from one cen- 

 tral source from which all rivers were equally furnished, 

 and to deplete one stream would only lead to a general 

 diminution. So far from this result being attained, how- 

 ever, the rivers of Florida were as crowded as ever while 

 the fisheries of the Hudson and Connecticut were almost 

 at an end. The converse of this experience was reached 

 when efforts were made to improve the supply of certain 

 streams. The artificial culture of shad in the Connecticut 

 and the Hudson, under the fishery commissions of those 

 States, has improved the yield in those rivers to a marked 

 extent, without having any effect on that of streams 

 further south or north. A few shad may have wandered 

 into the Hudson from the Connecticut, or vice versa, or 

 may possibly have strayed even further, but the benefits 



