4 XT. S. BUREAU OF FISHERIES. 



ties of whitefish are also taken in pound nets, trap nets, and seines. 

 A very large part of the catch reaches the market in a fresh condition, 

 although considerable quantities formerly were salted. The leading 

 centers of the trade are Chicago, Detroit, Sandusky, Cleveland, Erie, 

 and Buti'alo, whence the fish are shipped frozen or in ice to all parts 

 of the country. 



SPAWNING HABITS. 



The spawning season of the whitefish in the western end of Lake 

 Erie begins the early part of November and continues into December. 

 At this season there is a general movement of the fish to shoal parts 

 of the lakes, similar to the migration of anadromous fishes from the 

 ocean to the rivers. Some of the foreign whitefish are tj^pical an- 

 adromous species. After spawning the fish return at once to the 

 deeper water. 



The spawning habits of whitefish confined in pens have been ob- 

 served. The fish rise to the surface, occasionally in pairs, and rarely 

 in trios of one female and two males, the female emitting a quantity 

 of spawn at each rise. The males, always the smaller fish, per- 

 sistently follow the female and discharge milt at the same time the 

 eggs are emitted. 



IVliitefish reach maturity in the third or fourth year. A full- 

 grown specimen deposits from 10,000 to 75,000 eggs, depending on 

 its size. A rule for determining the approximate spawning capacity 

 is to allow 10,000 to 12,000 eggs for each pound of the fish's weight. 

 The eggs are one-eighth of an inch in diameter and are of an amber 

 color. They swell somewhat after impregnation. The number per 

 quart varies from 36,000 in Lake Ontario to 40,000 in Lake Erie. 



DESTRUCTION OF WHITEFISH SPAWN IN NATURE. 



In nature the eggs of the whitefish are subjected to the attacks of 

 many enemies for nearly five months. The mud puppy {Nectunis 

 m.aculatus) ^ commonly known as "lizard" or "water dog" by the 

 people along the lakes, is especially destructive. During the winter 

 months many of these animals are pumped up with the water supply 

 of the Put in Bay station. The stomachs of a considerable number 

 of them contain whitefish and cisco eggs. 



Another voracious destroyer of whitefish eggs is the common yel- 

 low perch {Perca flavescens) . The deck of a boat has been seen 

 covered with the eggs of whitefish and cisco pressed out of the 

 stomachs of perch taken the last of November from gill nets on the 

 reefs, where they had gone to feed on the eggs. 



The various smaller Cyprinidae and some other fishes, crawfish, 

 and wild fowl make the eggs of fishes a considerable portion of their 

 diet, and those eggs that require the longest period in hatching 

 suffer most. 



ARTIFICIAL PROPAGATION. 



The artificial propagation of whitefish has long since passed the 

 experimental state and has attained a high degree of perfection. 

 The work can be carried on with great flicility, and its value is 

 especially apparent when it is considered that under natural con- 

 ditions only a very small percentage of ,the eggs hatch, whereas 



