646 BULLETIN OF THE BUREAU OF FISHERIES. 
When it is desired to increase the production of domestic plants or animals, 
this is often most readily done by increasing the food supply. In other cases the 
result may be accomplished by creating a race of larger individuals, or one that 
breeds more rapidly. These two methods have been applied to domestic forms, 
but the first of them is often made use of also with game birds and mammals. 
The whitefish of the Great Lakes lives at depths of from 10 to 50 fathoms, scat- 
tered over an area of 25,700 square miles. (See p. 653.) Our knowledge of 
its mode of life, its daily and yearly movements, and its whereabouts during 
the growth period is meager. It is impossible, therefore, with present knowledge 
and under existing conditions, to attempt to increase the natural food of the 
whitefish. To suggest that it may be possible to produce a race of whitefish that 
would breed more rapidly than our present race, or appropriate food not utilized 
by the present whitefish, or occupy areas of the lake bottom now barren of 
whitefish, is to state a problem the solution of which must lie far in the future. 
The breeding of improved races of fish must begin with forms more readily con- 
trolled than the whitefish. There remain but two methods by which we may 
hope to increase the whitefish production of the Great Lakes, namely, to greatly 
increase the number of artificially hatched fry introduced into the lakes annually 
or to enact restrictive legislation which shall prevent the further depletion of 
productive waters and shall at the same time give an opportunity for depleted 
waters to become again productive. The present paper attempts a discussion 
of these two methods (2 and 3 of the foregoing analysis). 
METHOD OF INVESTIGATION. 
In undertaking an inquiry of this sort it is impossible to make personal inves- 
tigation of the whitefish in the field. The vastness of the areas involved and the 
depth at which the fish lives precludes this in the case of the individual investi- 
gator. He must necessarily base his work on data gathered by those who have 
worked with the help of the various state and national governments bordering 
on the Great Lakes. The problem is essentially one of statistics. The investiga- 
tor wishes to know what amount of whitefish have been taken in each part of the 
Great Lakes over a long period of years; what kinds and quantities of nets have 
been used in their capture; under what legislative restrictions these have been 
used; what quantities of young fish have been introduced into the Great Lakes 
and into each part of them to replenish the waters from which the adults have 
been taken. 
Fishing operations are carried on, or have been carried on, wholly by private 
individuals or corporations in the waters of the following States: Indiana, Illinois, 
Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin, as well as in 
the waters of the Dominion of Canada. ‘The fishery laws of these various govern- 
ments are diverse, and have been changed from time to time in the past. It is 
