652 BULLETIN OF THE BUREAU OF FISHERIES. 
food. The summer migration of the whitefish occurs apparently in all the 
Great Lakes. Milner (1874) reports it in Lakes Superior, Michigan, Huron, 
and Ontario, and Rathbun and Wakeham (1897) report it in Lake Erie. The 
date of its occurrence no doubt varies with the latitude. A second inshore 
migration occurs in the fall, taking place in November in the more southern 
latitudes and occupying about a month in any latitude. It is the spawning 
migration, during which the fish visit the shallower water to deposit their eggs. 
From Lake Erie this migration formerly extended to the St. Clair River and 
Lake St. Clair and it still extends into the Detroit River, but in the other lakes 
the location of the spawning grounds and the related extent of the migration 
are little understood. 
Milner states (1874, p. 85, 92) that the fish do not eat while spawning, or 
have very little in their stomachs. In this respect their habits are like those 
of many other Salmonide under like circumstances. If we accept this state- 
ment, then the food of the whitefish, except during the spring migration, is 
obtained within the depth range indicated above. During nine months of the 
year they are on this range; during June and July in southern latitudes and 
probably for a corresponding period in more northern latitudes they are engaged 
in the so-called spring migration; during one month (November in southern 
latitudes) they are engaged in the spawning or fall migration and during this 
time they do not feed or feed very little. The existence of the species therefore 
depends on the utilization of the range referred to. The capacity of any of the 
Great Lakes to produce whitefish must depend on the extent of this range, 
assuming the existence of suitable spawning grounds. If we accept Milner’s 
statement (1874, p. 61-62) that young whitefish of less than 114 pounds weight 
are found in water from 20 to 45 feet deep and thereafter enter deep water, the 
above proposition still stands essentially unmodified, for the production of 
commercial whitefish or breeding whitefish would still be in relation to the area 
of the range which furnishes them with food during nine nes in the year. 
These areas I shall refer to hereafter as whitefish areas. 
AREAS OF BOTTOM FREQUENTED BY WHITEFISH. 
In the accompanying maps (fig. 1 to 5) we have attempted to indicate the 
extent of the whitefish areas for each of the Great Lakes. These are the areas 
within which the fishermen find the whitefish when carrying on commercial 
fishing operations at other times than during the fall and spring migrations. 
They are the areas over which it is, or has been, profitable to fish, and outside of 
which the whitefish is found in relatively small numbers. The maps have been 
made by tracing the appropriate fathom lines on the United States engineer 
charts of the Great Lakes. They are sufficiently explained in the legends 
