GREAT LAKES COREGONIDS 



501 



Size variations. — In Table 74, 10 specimens less than 200 millimeters in length 

 and 10 specimens more than 225 millimeters in length have been compared extensively, 

 and in Tables 8 to 11 all the individuals less than 225 millimeters are compared in 

 certain characters with those of 225 millimeters or more. Figures for the more 

 important systematic characters that can be expressed numerically are abstracted 

 below : 



L/H: 



Large fish, (4.1) 4.3-4.7 (5.2). 

 Small fish, (4) 4.2-4.6 (4.8). 

 H/E: 



Large fish, (3.6) 4.1-4.4 (5.1). 

 Small fish, (3.4) 4-4.2 (4.5). 

 H/M: 



Large fish, (2.5) 2.7-3 (3.1). 

 Small fish, (2.5) 2.7-3 (3.2). 



H/S: 



Large fish, (3.4) 3.6-3.9 (4.3). 

 Small fish, (3.5) 3.6-3.9 (4.1). 



Pv/P: 



Large fish, (1.7) 2-2.2 (2.8). 

 Small fish, (1.6) 1.9-2.2 (2.3). 

 Av/V: 



Large fish, (1.3) 1.6-1.8 (2.3). 

 Small fish, (1.4) 1.5-1.8 (1.9). 

 L/D: 



Large fish, (3.7) 4.3-5 (5.9). 

 Small fish, (4) 4.6-5 (5.2). 



A study of these tables shows that the differences between the two groups is 

 slight. The head and eye are proportionally somewhat larger and the depth some- 

 what less in smaller individuals. The paired fins possibly are also a trifle longer. 



No specimens smaller than 190 millimeters have been found to be sexually 

 mature, and the majority of those under 200 millimeters have been immature. 



COMPARISONS 



Typical artedi may be distinguished readily from any other Leucichthys in the 

 lake. The differences between artedi and the other species of Leucichthys are given 

 under the heading "Comparisons" in the accounts of these species. 



GEOGRAPHICAL DISTRIBUTION 



The herring of Superior occur in schools, as in the other Great Lakes, and the 

 species is as widely distributed in Lake Superior. At Bayfield, Wis., and Port 

 Arthur, Ontario, they are so abundant that extensive fishing operations are con- 

 ducted for them during the fall; and at several other ports, particularly along the west 

 shore, they are taken at some time of the season in commercial quantities. Speci- 

 mens have been collected from every one of the 12 ports visited. The data for these 

 are given in Table 73 and are shown platted on the map of the lake in Figure 3. 



MODE OF CAPTURE 



Virtually all herring caught in the lake are taken by means of gill nets. Except 

 in Michigan, where 2%-inch nets usually are employed, the regulation mesh is 2% 

 or 2% inches. The nets are used on the bottom, as in the other upper lakes, except 

 in the western waters, where it has been the custom for several decades to float them 

 below the surface. This practice has been followed not only in summer but also in 

 fall. The descent into deep water on the western Minnesota shore is precipitous 

 virtually everywhere, and this bydrographic condition no doubt has forced the 

 herring to a more strictly pelagic life than in localities where shoals obtain. The 



