GREAT LAKES COREGONIDS 



525 



from cursory examination in the field, to have more pointed snouts, but no data on this 

 subject were collected in the field, and in preserved specimens the snout is inclined 

 to be mechanically distorted. However, races may be quite as well marked by 

 physiological differences. Additional discussion on this subject will be found under 

 "Breeding habits." 



Size variations. — In Table'85, 10 specimens of various sizes are compared in their 

 chief characters. Separating collected specimens into two size groups, with the 

 dividing line at 300 millimeters, the range of certain proportional characters for the 

 two groups varies more or less. These averages, where they tend to be different, are 

 abstracted below: 



L/H: 



Small fish, (4.3) 4.5-4.8 (5). 

 Large fish, (4) 4.7-5. 

 H/E: 



Small fish, (3.8) 4.1-4.5 (4.6). 

 Large fish, (4.2) 4.6-5 (5.3). 



H/S: 



Small fish, (3.4) 3.6-4 (4.4). 

 Large fish, (3.2) 3.4-3.7 (4.2). 

 L/D: 



Small fish, (3.4) 3.8-4.3 (4.9). 

 Large fish, (3.3) 3.7-4.1 (4.7). 



The most conspicuous changes involve the head-eye relation, which shows the 

 eye to decrease in relative size with growth. The head and depth appear to be 

 altered but little relative to the body length. From the figures the snout appears to 

 be proportionally shorter in small specimens, but these results are not conclusive, as 

 the snout in large individuals often is deformed in preservation, and slight distortions, 

 even to the extent of a millimeter, would affect the proportions seriously. 



METHOD OF CAPTURE 



The same methods of capture are employed on Lake Huron as on Lake Michigan 

 and the other lakes. Pound nets in the North Channel and in Georgian Bay yield 

 the greatest production, while on the American shore trap nets figure more extensively 

 as an effective apparatus than on Lake Michigan. Gill nets in the lake are of 43^-inch 

 or larger mesh and depend for profitable use on their catches of whitefish and trout. 

 They may, however, take whitefish on their spawning grounds only, or their catches 

 may be predominantly of whitefish out of a few ports for a short period at other 

 seasons. 



GEOGRAPHICAL DISTRIBUTION 



We have the assurance of the fishermen that the whitefish formerly occurred all 

 along the shores of Lake Huron, the North Channel, and Georgian Bay. To-day it 

 is virtually unknown from long stretches of the shore line, and in only a few areas 

 does it still remain in numbers. There are two such areas where the fish are fairly 

 abundant on the American shore — in Saginaw Bay and off Alpena — and one of 

 greater extent on the Canadian shore, in the northern and eastern portions of Geor- 

 gian Bay. 



I have collected specimens from most of the ports visited. The data for these 

 are given in Table 84. 



SEASONAL MOVEMENTS 



The schools of whitefish in Lake Huron, as in the other lakes, engage in migra- 

 tions toward and away from the shores during the season. From the users of the 

 various types of fishing apparatus I have collected data on these movements. 



