106 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



The statistics lierein given, showing the extent of the shad fisheries 

 in 1896, which is the year referred to in this report when not otherwise 

 mentioned, were obtained by agents of the United States Fish Com- 

 mission. Valuable assistance has been received from Messrs. Ansley 

 Hall, John N. Cobb, and H. O. Weaver, of the Commission. 



MIGRATIONS OF SHAD. 



The shad belongs to the migratory class of fishes, being found in the 

 coastal waters during only a portion of each year. In their annual 

 migration mature shad appear in the southern rivers of the United 

 States in December and January, and as the season advances they 

 appear successively in the various streams, reaching the New England 

 waters about May 1. After remaining in the rivers several months 

 they disappear, renewing the performance the following season. 



The young fry, hatched out in the rivers in spring and early summer, 

 remain there until the following fall, when they leave for the ocean, 

 and nothing more is seen of them until they return to the estuaries as 

 mature or nearly mature fish, supposed to be two or three years old. 

 Their habitat from their disappearance on the coast in the summer and 

 fall to their reappearance in tlie following winter or spring is unknown. 

 It is likewise unknown whether, as they disappear from the estuaries, 

 they remain nearby or go far off from the shore, or whether they retreat 

 in a direction parallel with the coast to the warmer waters of the South. 

 Neither has it been established whether individual shad visit the rivers 

 every year or every two years, but the depletion by casualty and capture 

 is so great that probably only a small proportion ever ascend the rivers 

 a second time. 



In accordance with the old-time theory that all seasonal migrations 

 were directed toward and from the equator, it was foi'raerly considered 

 that the entire body of shad wintered in the South and started north- 

 ward in a vast school at the beginning of the year, advancing along the 

 coast iu almost military array, sending a detachment up each succes- 

 sive stream, this division, by a singular method of selection, being the 

 individuals that were bred in those respective streams, the last portion 

 of the great school entering the Gulf of St. Lawrence. 



But zoologists now recognize a second kind of seasonal movement, 

 termed ^'bathic migration," by which uniformity of temperature is 

 secured far more readily than by moving toward or from the equator; 

 and the present theory is that the young shad hatched out in any par- 

 ticular river remain within a moderate distance off the mouth of that 

 stream until the period occurs for their inland migration, and that the 

 schools offish are generally distributed off the coast at all times, enter- 

 ing the rivers as soon as the temperature of the water is suitable. 

 Their appearance first in the extreme southern river of the coast, the 

 St. Johns, and at later dates successively iu the more northern rivers, 

 seems to confirm this view. There are exceptions to this order of 



