448 



the deep waters of the lakes. In the fall, and just before the spawning season, 

 various minute shell-fish would appear to constitute the bulk of their food. 



The places selected for spawning grounds are honey-combed rocks or 

 gravelly bottoms, in water of 30 to 50 feet depth, the crevices in which afford a 

 safe place of lodgment for the eggs and protect them to a certain extent from 

 the watchful spawn-eaters, the suckers, lake herring and lake lizards or Meno- 



Fig. 12.— Canadian Lake Lizard, oe Mknobranch. [Necturus vmculatus.) 



branchs (fig. 12). On the north shore of Lake Superior the mouths of the great 

 rivers, like the Michipicoten and Neepigon, are favourite places ; possibly a relic of 

 a former anadromous habit, such as characterises other Salmonoids. To cope 

 successfully with the destructive spawn-eaters large numbers of eggs are deposited, 

 although many of them are destined to destruction. It has been calculated that 

 a female Whitefish sheds 10,000 for every pound of her weight 



It is possible that the spawning habits in the rivers and lakes differ, the 

 fish exhibiting greater activity in the former than in the latter. In both, how- 

 ever, they pair, the male being uniformly much smaller than the female. In the 

 Detroit River the fish are described as jumping in pairs at night, the male swim- 

 ming along beside the female with his snout up towards the pectoral fin, and 

 both suddenly leaping from the water, spawn and milt running from them the 

 while. In Lake Ontario, on the other hand, the female has been described as 

 ploughing a nest in the gravelly bottom, where she remains for two or three 

 days until all the eggs are deposited. Possibly the spawning habits of the vari- 

 ous species differ, but sufiicient attention has not been given to the subject. 



In contrast with the short period of development described for the Clupeoids 

 (p 445) the Whitefish eggs require about 100 days to hatch out at the natural 

 temperature of the water. They thus escape from the egg about the beginning 

 of April, and have entirely absorbed the yolk-sac by the end of that month, 

 when they have reached the length of half an inch. 



The little minnows thereafter make for deeper water, but it is stated that 

 the fish do not seek the greater depths until they have attained a weight of over 

 a pound ; many of these immature fish are therefore caught in pound-nets, while 

 the gill-nets secure no fish under a pound in weight. 



The principal enemy of the Whitefish after it has attained maturity is the 

 Lake Trout, but the small fry are undoubtedly eagerly eaten by the Bass and 

 Percoid fishes, as long as they remain within their reach. 



Occasionally Whitefish have been observed to die in large numbers. Prof. 

 A. G. Lawson brought me specimens of a parasitic crustacean {Argwlus coregoni ?) 

 some years ago which was obviously the cause of death of immense numbers of 

 whitefish in the Lake of the Woods, and a similar phenomenon is recorded from 

 lakes in Minnesota. Whether this is a frequent cause of such epidemics remains 

 still to be investigated. 



