79 2 POPULAR SCIENCE MONTHLY. 



and used these fisheries long before the first white settlers found 

 them at work with their rude seines. In the early part of this cen- 

 tury, 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 one 

 thousand to twelve hundred dollars a year to their owners. There 

 is a record of the capture, at a single haul, of ten thousand shad 

 at one of these fisheries on Fire Island, near Wilkesbarre. Dams 

 across the river have excluded the shad from more than two hundred 

 miles of the course of the Susquehanna, and the profitable fisheries 

 now reach for only a few miles above the boundaries of Maryland, 

 while the shad are cut off from many of the best breeding grounds, 

 which are the sandy flats near the shores of streams and the sand 4 

 bars which lie in their course. The fishes run up into these places 

 in pairs in the early evening after sunset, and the eggs are thrown 

 into the water while the fishes are swimming about, but they soon 

 sink to the bottom and develop very rapidly. The number of eggs is 

 about twenty-five thousand, but a hundred thousand have been ob- 

 tained from a single large shad. Few adult shad escape all the dan- 

 gers of their journey, and these few are so battered and emaciated 

 that they have no value as food, and are unknown in our markets, 

 which are supplied with those that are captured on their way upward. 

 The young fish remain in the rivers until late in the fall, feeding 

 upon small Crustacea, the larva? of insects, the young of other fishes, 

 and minute active animals, and they grow to a length of two or 

 three inches by November, when they leave our waters for the ocean. 

 The shad is a marine fish which has acquired the habit of laying its 

 eggs in fresh water, out of reach of the innumerable enemies that 

 abound on the shoals and sand bars of the seashore. Since the eggs 

 are abandoned by their parents soon after they are laid, prolonged 

 residence at the breeding grounds is not necessary, and the shad has 

 thus been able to utilize safe places which supply no proper food 

 and are unfit for prolonged residence. If it were compelled to incu- 

 bate its eggs and to guard and protect and feed its nestlings like a 

 bird, it would have been restricted to some breeding place fitted for 

 more prolonged residence, and we should then feel something of the 

 same tendency to call its birthplace its true home that we experience 

 in our study of birds. We should refer the migration to this place 

 as the starting point, and we should try to discover some reason why 

 they spend part of the year elsewhere. 



Most animals owe their existence to the occurrence, in their 

 natural home, of all that their life requires, but the power to traverse 

 great distances at great speed, and to pass over all the barriers of 

 land and water, joined to their comparative indifference to changes 



