110 THE FOUNDATIONS OF ZOOLOGY 



Since the number of shad which enter a river in the spring 

 is out of all proportion to its resources as a feeding ground, we 

 might say of them, as we are disposed to say of birds, that they 

 leave their birthplace in search of food ; but as they find so little 

 proper food in the rivers that it may be said with almost literal 

 exactness that they make their journey fasting, it is quite plain 

 that this is the wrong point of view; that we must believe that 

 they enter the rivers to lay their eggs, and that we must see in 

 this, and not in the return journey to the ocean, the purpose of 

 their migration. 



As the shad is a marine fish which does its eating at sea, 

 and as its visits to fresh water are only for the purpose of repro- 

 duction, the numbers which make their way up the rivers bears 

 no comparison to the capacity of the streams for supplying them 

 with food. When it visits our coast in the spring, it enters the 

 mouths of our rivers in great schools, and it journeys up them 

 to a surprising distance ; the total length of the journey from the 

 sea to the spawning ground and back again often exceeds a 

 thousand miles, and this journey is made almost or quite without 

 food. Many of them, and among these the largest ones, go on 

 and on until they reach some insurmountable obstacle, such as a 

 water-fall or a dam, or until they reach the sources of the river. 

 Before dams were built in the Susquehanna River, many shad 

 which entered the Chesapeak Bay at the Capes continued their 

 long fasting journey across Virginia and Maryland and Pennsyl- 

 vania, into the state of New York, and travelled through more 

 than five hundred miles of inland waters before they reached the 

 end of their journey upwards. 



Fragments of Indian pottery, stamped with a pattern made 

 by the impression of a shad's backbone have been found in 

 southern New York, and the number of stone net-sinkers which 

 have been picked up in the Wyoming valley shows that the 

 Indians had known and used the shad-fisheries long before the 

 first white settlers found them at work with their rude seines. 

 In the early part of this century, before canals and the dams 

 which supply them were made, there were forty fishing stations 

 beyond the forks of the Susquehanna in northern Pennsylvania, and 

 some of them were worth from $1000 to $1200 a year to their 



