286 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



issued by the United States Commission of Fish and Fisheries, in which 

 the methods and apparatus are described and full statistical data are 

 given. Detailed statistical and descriptive matter relating to the 

 whitefish fisheries of Canada will be found in the annual reports of the 

 Department of Marine and Fisheries. 



The body of water supporting the most extensive whitefish fisheries 

 in the United States is Lake Michigan. Up to a comparatively recent 

 year Lake Erie took precedence, but the serious decline in that lake 

 has brought Lake Michigan to the front. Lake Erie ranks second, fol- 

 lowed by lakes Huron, Superior, Ontario, and St. Clair, in the order 

 named. 



The aggregate quantity of whitefisbes taken for market in the United 

 States and Canada is now more than 76,000,000 pounds annually, with 

 a value of over $2,400,000. These figures are based on the known yield 

 in the Great Lakes and the British North American provinces in 1893 as 

 given in the official reports, and in other parts of the United States in 

 1894. If to this catch is added the large quantities consumed locally 

 by Indians, Eskimos, and others in Arctic America, Alaska, and the 

 Western States, the total annual output of whitefishes in North America 

 probably amounts to not less than 83,000,000 pounds, having a value of 

 $2,800,000. 



THE GENERA AND SPECIES OF AMERICAN WHITEFISHES. 



The range of variation among the individuals of each of the species 

 of this group is very much greater than has usually been supposed. 

 An examination of a large series of almost any one of the species shows 

 astonishing differences, even among individuals taken in the same net 

 and at the same time. Aside from the usual variations due to differ- 

 ences in age, sex, and season, there are other variations which manifestly 

 bear no relation to those causes, and which are also independent 

 of geographic influences. Among these are variations in the size of 

 the mouth, the length and relative width of maxillary and mandible, 

 the prominence of the lower jaw, and, most unexpected of all, a very 

 considerable variation in the number and length of the gillrakers. 

 The range in the number of scales in a longitudinal series is also very 

 great. An examination of the tables of comparative measurements, 

 which we give in connection with our discussion of the different species, 

 will make plain the details of these diverse and extensive variations. 



The most important characters which are used to separate the differ- 

 ent species of whitefishes are the following: Size aud shape of the 

 mouth, size of the mandible, maxillary, and eye; relative length of the 

 head and snout; size and position of the different fins; the teeth; the 

 number and length of the gillrakers; the number and character of 

 scales; the color; and the general form of the head and body. 



