20 tr. S. BUREAU OF FISHERIES. 



Maine; the headwaters of the Columbia and Eraser Rivers and 

 streams of Vancouver Island; and even waters within the Arctic 

 Circle are said to contain this species. The present paper discusses 

 the trout of the Great Lakes and the methods employed in its arti- 

 ficial propagation at the bureau's stations on Lake Michigan, at 

 Charlevoix, Mich.; on Lake Superior, at Duluth, Minn.; and on 

 Lake Ontario, at Cape Vincent, N. Y. 



DESCRIPnON. 



This handsome species {Cristivomer namaycush), the largest of 

 the trouts, is classed with the charrs. It has an elongated body, 

 the length being about four and one-half times the depth. The head 

 is large, flat above, and about as long as the body is deep. The 

 mouth is large; the maxillary bone extends beyond the eye and is 

 half the length of the head; the jaws have strong teeth. A pe- 

 culiarity of the vomerine bone distinguishes this fish from the genus 

 Salvelinus; it has a crest provided with teeth extending backward 

 from the shaft of the bone. On the hyoid bone the teeth are in a 

 cardiform band. Hie eye, placed near the top of the head, is con- 

 tained only about four and one-half times in length of head. The 

 caudal fin is well marked. Both the dorsal and anal fins contain 

 9 to 11 rays. In the straight lateral line there are about 200 scales. 

 Branchiostegals 11 to 12. 



The coloration is quite variable in fish from different localities. 

 The general color is usually dark gray. The body, head, and fins 

 are covered with small, discrete rounded spots, usually of a pale color 

 but often tinged with reddish. On the back and top of head there 

 are fine vermiculations, as in the brook trout. Examples fi-om some 

 lakes of Maine and eastern Canada are nearly black, and Alaskan 

 examples are often very dark; others are quite pale. This fish is 

 known in Maine and other sections of New England under the name 

 of " togue," and in Canada as the gray trout. 



That variety of the lake trout known as the siscowet (CristlvoTner 

 namaycush siscotvet) , found only in deep water in Lake Superior, 

 is shorter and paler than the typical fish and has weaker teeth and 

 a shorter head. It is, however, chiefly characterized by an excessive 

 fatness, which greatly reduces its food value. 



INFLUENCE OF ENVIRONMENT. 



The nature of the environment has a decided influence on the 

 characteristics of the lake trout, the temperature of the water, the 

 food, and the character of the bottom entirely changing the mark- 

 ings and peculiarities of the fish in its various habitats. 



FOOD. 



Until recently it was commonly thought that the principal food 

 of the lake trout was the young whitefish, and for this reason the 

 fishermen of the lakes were generally unfavorable to its artificial 

 propagation. The error of that belief is now generally conceded, 

 though no doubt quite a number of young whitefish become food for 



