GREAT LAKES COREGONIDS 



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tion of aquatic habitats, and as these are, for the most part, of considerable extent, 

 it was to be expected that the maximum number of Great Lakes forms would be 

 found here. In addition to this, there are many fishing ports on the lake, and out 

 of most of these various kinds of apparatus are in use, in shallow water as well as 

 in the deeper waters, so that a considerable variety of species is taken at such ports. 



The investigations were extended subsequently to the other lakes. In Lakes 

 Michigan and Erie the commercial fishing operations are at least as extensive and 

 varied as in Lake Huron, but in Lakes Superior, Nipigon, and Ontario the smaller 

 species of fishes, including Leucichthys, are sought for but little by commercial fish- 

 ermen, so that on the latter lakes I was compelled to make use of special apparatus. 

 The lakes themselves differ considerably in their physical characteristics and conse- 

 quently are not equal in productivity. 



Lake Nipigon 



Lake Nipigon, in Canadian territory, is the smallest and most northerly, as well 

 as one of the shallowest, of the series of lakes considered in this paper. It is about 

 65 miles long by 40 miles wide, but its area is much interrupted by numerous islands 

 and shallow bays, so that the total water surface is only about 1,530 square miles. 

 Throughout most of its area the depth is less than 30 fathoms, though small areas 

 are known with a depth of about 60 fathoms. It is connected with Lake Superior 

 through the Nipigon River, but a fall at the river's source probably prevents the 

 interchange of members of the fish fauna. The Canadian authorities opened the 

 lake to commercial fishing in 1916 and have attempted to regulate the number of 

 fishing boats and the maximum output. The annual production, which so far has 

 been principally whitefish and trout, has averaged around 1,500,000 pounds, of 

 which the true whitefish has constituted more than two-thirds. 



Lake Superior 



Lake Superior lies at the head of the Great Lakes and is the largest, deepest, 

 and coldest of the chain. Its northern and eastern waters are controlled by the 

 Province of Ontario, those on the south by the States of Michigan and Wisconsin, 

 and those on the west by Minnesota. It receives the waters of Lake Nipigon to the 

 northward and drains through St. Marys River into the North Channel. The lake 

 is broadly crescentic in shape, with a length of about 355 miles and a width on the 

 western half of about 70 miles and on the eastern half of 90 to 110 miles. Its area 

 is about 32,000 square miles. The main body of the lake is more than 100 fathoms 

 in depth, and a sounding of 196 fathoms has been recorded. The shore on the outer 

 curve of the crescent is precipitous, and at many points a 100-fathom depth can be 

 reached within 2 miles of land. The bottom slopes more gradually from the south- 

 ern shore, and the 50-fathom contour is on the average about 5 or 6 miles out. There 

 are several bays and a number of large islands in the lake, in and around which 

 conditions are more tempered than in the lake itself. These areas, however, are 

 relatively insignificant, and the only important stretches of shallow water lie in the 

 Apostle Islands region, Whitefish Bay, and in the bay region on the north shore. 

 The shores are rocky for the most part, except on the south, where there are broad 

 stretches of sand, gravel, and clay. Most of the bottom in the deeper parts is clay. 



