58 FISH—CULTURAL ASSOCIATION. 
As regards all the anadromous species, however, which are 
the object of commercial fisheries, viz.: the salmonida, the shad, 
the herring or alewife, etc., it is necessary that the young, after 
hatching, should remain for some time in our fresh waters, 
feeding and growing, and of course, finding the necessary food 
in these waters: The extent of the breeding’ and feeding ‘area 
of any river basin is, therefore, necessarily the measure of its 
possible productiveness. .A given area when pressed to its 
maximum of production cannot provide for more than a given 
number of individuals. The extension of the area of production 
is, therefore, the rational means by which we may determine 
permanent increased productiveness. Hence arises the necessity 
for fish-ways, which are, in short, various constructions designed 
for the purpose of enabling different species of fish to surmount 
obstructions which would be otherwise impassible to them. 
A fish-way to be effective must fulfill certain conditions, 
which are clearly stated by Mr. C. G. Atkins in an admirable 
article on the subject of fish-ways, published in the anuual 
report of the United States Fish Commission for 1872-73, as 
follows: 
“First—It must be accessible; that is, the foot of the fish-way 
must be so located that fish will readily find it. 
‘“Second—It must discharge a sufficient volume of water to 
attract fish to it. 
“Third—The water must be discharged with such moderate 
velocity, that fish may easily enter and swim against the current.” 
To the conditions above stated we may add: Fourth—The 
route to be travelled by the fish should be as short and as direct 
as possible, and the floor of the fish-way should simulate as 
nearly as may be the bed of the stream. 
The first condition may be always fulfilled in the location, by 
arranging so as to have the discharge of water from the fish-way 
in a line with or in the immediate vicinity of the obstruction. 
The second condition is more embarrassing. The larger the 
volume of water discharged through the fish-way the better it 
will be. 
In the plans of fish-ways which are common cuecatteetl New 
England, the volume of the discharge is necessarily limited by 
