98 American Fisheries Society 



(2) Artificial restocking of depleted streams and the creation 

 of new fisheries in favorable localities. 



(3) Adequate and efficient methods of regulating the fishery. 



In the spring of 1919, the work which had been suspended dur- 

 ing the war was resumed, and first of all the important problem of 

 obtaining a clear passageway for the fish to the spawning grounds, 

 as a preliminary requisite for stocking was taken up. At the same 

 time preliminary cultural work, including the artificial hatching 

 of alewife eggs guaranteed beyond a reasonable doubt the future 

 success of restocking the depleted streams. 



FISH WAYS. 



The first step in the reconstruction of the alewife fishery is 

 the removal of existing obstructions to make a clear passageway 

 for alewives. Two conditions present difficult problems — impas- 

 sable dams and pollution. The first and most important has been 

 met by installing workable fishways, the latter is still unsolved. 



Requirements. — The requirements for a successful fishway are: 



(1) Easy and rapid passage for all species of fish, with uniform 

 flow of water, gradual ascent, and absence of high barriers. (2) 

 A minimum sacrifice of water in the interest of the dam owners. 

 (3) An entrance into which the fish are readily directed. (4) A 

 firm, solid construction, resistant to freshets, or one which may 

 readily be removed when not in use. 



Installation. — The chief point to remember is that it is not the 

 type of fishway, but how it is installed, which determines its success 

 or failure, since each dam presents certain peculiarities which 

 necessitates individual treatment. In installing a fishway the 

 following conditions must be considered: 



(1) Water Flow. — Provision for a constant flow of water, 

 irrespective of variations in the level of the pond, can be made by 

 an adjustable upper section of the fishway to correspond to the 

 water level, a gate situated at the lowest probable water line, or 

 several gates at different levels. 



(2) Entrance. — Instinctively the fish follow the greatest flow 

 of water, usually up the main stream to the dam. Therefore, the 

 entrance must be either directly beneath the dam where the fish 

 will naturally swing into it, or there must be some means of 



