216 NEW ENGLAND FISHERIES 



the shad is anadromous ascending rivers for the purpose 

 of spawning when it may be taken by the farmer-fisher- 

 man at his very door, hundreds of miles from the coast. 



Within the last half century, the abundance of shad in 

 our rivers has been greatly affected by the agency of man, 

 especially in the rivers where dams have been constructed 

 and on which certain mills have been built. In the early 

 part of the last century shad used to enter and ascend the 

 rivers until they met with impassable falls or reached the 

 head waters of the stream. They were taken at all points 

 along the run. The most important agencies that have 

 brought about a limitation of the range of shad in rivers 

 are insurmountable dams, the pollution of water by manu- 

 facturing plants and the sewage of cities, agricultural 

 operations that, carried on near the rivers, cause the waters 

 to become muddy during the spawning seasons, and the 

 extensive fisheries usually placed at the mouths of rivers. 

 In a few rivers the development of the water power has 

 resulted in completely exterminating the anadromous fishes, 

 this being the case in the Thames, the Blackstone, the Saco, 

 and the Merrimac. In the case of the Connecticut, the 

 abundance of the shad has decreased greatly since the 

 building of the dam at Holyoke in 1849. The fish were 

 thus prevented from ascending the river above the dam and 

 for several years were caught in greater abundance at 

 points below the obstruction. But from the six years 

 from 1865 to 1870 the annual catch averaged 4,482 shad, 

 less than one-half the former yield. The record of the 

 catch on the Connecticut from 1853 to 1896 shows that the 

 total yield below the dam decreased from nearly 500,000 

 annually to an average of less than one-tenth of that num- 

 ber. 1 



iThe Shad Fisheries of the Atlantic Coast, pp. 112-113. 

 How the range of shad in New England rivers has been cut down 

 is apparent from the following tables, exhibiting the original and 



