46 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Stomach before tbey were taken from the water. Fish from the gill- 

 nets have generally the food in the stomach only partially digested, 

 while a hundred fish in succession from tbe pound-nets may be opened 

 and every stomach found empty. 



It is frequently asserted that aquatic vegetation afforded sustenance 

 to the white-fish. The investigations in the past two years did not 

 result in any confirmation of this notion, and it would not accord with 

 the habits of any species of the family of fishes to which the lake white- 

 fish belongs. 



(22 c.) The migrations of the white-fish. — The assertion was sometimes 

 made among the fishermen that the scarcity of white-fish at any one 

 locality was no reliable indication that the number had decreased, but 

 that the schools had probably migrated to some other region. 



At Waukegan, Ills., the white-fish come into shallow water in the 

 greatest abundance in the months of June and July. The same habit 

 is observed in various localities on the lakes, though by no means at all 

 points. Several places on the shores of Lake ]\Iichigau, in the south 

 half of the lake, in the vicinity of the Apostle Islands, Lake Superior, and 

 at the Thunder Bay Islands of Lake Huron may be referred to as locali- 

 ties where the July migration occurs. George Keith, Esq., a factor of the 

 Hudson Bay Company, at Michipicoten, in 1840, affords Sir John Richard- 

 son the same information in the habits of a species of the Goregonus. It 

 was for a long time a ditficult matter to discover the reason for this suin- 

 mer run on the shore, if, indeed, it has yet been correctly accounted for. 

 The contents of the stomach were found to be the same as at other 

 seasons of the year. It was not probable that the white-fish was an 

 exception to all its congeners of the Salmonoid family, and jireferred 

 the warmer temperature of shallow water to the colder waters outside. 

 Besides, the schools of white-fish were always found to leave a region 

 where wide areas of shoal- water existed as the heat of summer advanced. 

 The theory adopted to account for this summer visit to the shore was 

 that the calm, quiet weather of the summer months, from the slight dis- 

 turbance of the surface, prevented the amount of aeration to the water 

 that occurred at other seasons of the year, and the fish sought the shore 

 where the splashing on the beach and sand-bars supplied the water with 

 the requisite amount of air, just as other species of this family of fishes 

 delight in rapids and falls, because the breaking up of the masses of 

 water supplies it with a large amount of respiratory gases. 



In waters like Lake Erie, where, according to the lake-survey, the 

 temperature attains as high as 75°, the white-fish seek the cooler deep 

 waters in the summer, and I have not learned of a migration upon the 

 shore at any point, they, perhaps, preferring a less amount of aeration 

 to a high degree of heat. 



The fact that in the month of August the v. hite-fish of the Sault Ste. 

 Marie Eapids leave the river entirely, and do not return until in Septem- 



