LX REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



isted have disappeared before tlie encroachments of man. Cities have 

 grown up along its banks which each year discharge into its waters an 

 increasing vohime of sewage, gas tar, and other deleterious substances 

 to pollute the water and render it unfit for healthy development of the 

 eggs that may be deposited. Large seines occupy every reach where 

 the fish congregate to spawn, or stretch their broad arms across the 

 channel to intercept the schools of shad and herring in their upward 

 migrations. From every headland jjound nets stretch their meshes a 

 thousand feet or more from shore to guide the unwary fish into the 

 traps, which are set on the edge of, and often in, the navigable channel. 



Hundreds of gillers, with nets a hundred fathoms long, stretched 

 across the channel, drift up and down, on ebb and flood, unceasingly, 

 and with their finQ-spun nets, almost invisible, obstruct ascent as effect- 

 ually as if strong dams of stone or timber barred the passage. 



Such being the condition of things on the Potomac at the present 

 time, the conclusion was readily reached that if the spawning grounds 

 of the shad and herring could be enlarged by taking in the lung reaches 

 of river that lie above the Great Falls a great gain could be secured. 

 This, however, could only be done by providing convenient passage for 

 them over or around this obstruction. 



Accordingly, when the necessity of an increased water supply for the 

 city of Washington was brought before Congress by the Commissioners 

 of the District of Columbia, I addressed a letter to Maj. W. J. Twining, 

 then Engineer Commissioner of the District, calling his attention to the 

 propriety of including, in any proposition for the completion of the dam 

 at the Great Falls, the construction of a suitable fish-way to admit the 

 ascent of shad, salmon, striped bass, herring, sturgeon, etc., to the upper 

 waters of the Potomac Eiver. Sut)sequently, in response to the invi- 

 tation of the Committee on the District of Columbia in the House of 

 Eepresentatives, I addressed them the following communication: 



"D^'iTED States Commission Fish and Fisheries, 

 WasMngto7i, I). C, June 1 , 18ti2. 

 Hon. Henry S. Neal, 



Chairman Committee on District of Columbia^ 



House of Representatives : 

 Dear Sir : In response to the inquiries made by your committee 

 through the Hon. Mr. Garrison, I would submit the following: 



In 1871, in compliance with an act of Congress, I was designated by 

 the President to conduct an inquiry into the causes operating to dimin- 

 ish the supply of food-fishes on the sea-coast and the lakes of the United 

 States. The investigations had made but little progress before I became 

 convinced that the obstructions in our rivers, whilst not the only cause, 

 were one of the main factors in determining the reduction in the num- 

 bers both of the anadromous fishes, such as the salmon, shad, and her- 

 ring, and the salt-water species, the food of which consists largely of 

 the anadromous species referred to. In the case of the salmon, shad, 

 and herring (alewives) the effect was direct and immediate. The ob- 

 structions in some rivers have entirely excluded these fishes from their 



