GREAT LAKES COREGONIDS 



535 



move them up and down the banks. In spring and fall the fish are likely to be 

 shallowest and in midsummer deepest, though the fishermen say they are not able, 

 usually, to go shallower than 15 fathoms or they will load their nets with suckers, 

 and deeper than 35 fathoms they seldom find whitefish in commercial quantities. 

 However, several fishermen claim to have made profitable lifts from depths of 40 

 and even 45 fathoms. 



BEEEDING HABITS 



According to John Mclver and Andrew Sutherland, the whitefish spawn from 

 the middle to the end of November. They select hard bottom and come into the 

 shallowest water at that time. Nothing is known of their spawning behavior. 



The Nipigon fish do not grow large. One of the largest specimens ever collected 

 measured only 615 millimeters and weighed probably about 10 pounds, while speci- 

 mens over 4 pounds are relatively uncommon. It is not known definitely at what 

 size the fish mature sexually, but Mr. Mclver says they may be sexually mature at 

 less than 2 pounds in the round. I have only nine fish over 300 millimeters long, 

 three of which have been eviscerated ; and of the six fish in the round two males and 

 a female of each group are immature at a length of 317, 325, and 321 millimeters, 

 respectively (weight about 1 to 1.34 pounds), while the mature fish measure 331, 

 409, and 373 millimeters, respectively. All fish smaller than 300 millimeters uni- 

 formly show no maturity of the gonads. Superficial examination indicates, also, 

 that the fish grow slowly. A slow rate of growth might be expected for fish from 

 waters that are covered with ice for so long a period each year. 



ABUNDANCE 



The whitefish is the most important and most abundant commercial fish in 

 Lake Nipigon. No other fish are marketable, except the lake trout and wall-eyed 

 pike. Leucichthys of several species and suckers are very abundant but are not 

 yet commercially valuable at points so far removed from the markets. 



The lake was opened to commercial fishing in 1916. Production was insignificant 

 that year, but for most of the time since the fisheries have been prosecuted by some 

 dozen steam and gasoline boats operating gill nets. The number of fishing licenses 

 has been limited more or less, and the production of the boats has been restricted 

 to 80 tons a year per steam tug and 40 tons per gasoline vessel. The peak of pro- 

 duction was reached in 1919, according to the Ontario report upon game and fisheries, 

 when 1,620,970 pounds of whitefish, 617,900 pounds of trout, and 30,035 pounds of 

 wall-eyes were taken. Figures for 1920 and 1921 show a continued decrease. 



If all the whitefish grow as slowly as my specimens indicate, the reason for the 

 decline in production is obviously due to the fact that the fish have been caught more 

 rapidly than they were being produced, and in that case a serious depletion may 

 be expected soon. 



Coregonus clupeaformis of Lake Erie 



The whitefish of Lake Erie is very similar to the Michigan form except that it is 

 deeper bodied, as a rule, and the predorsal contour, therefore, is often strongly arched 

 in smaller fish. Fish may be "bowbacked" as small as 2^ pounds round. All the 

 whitefish are by no means thus humped at the nape, and often specimens weighing 



