FISH-CULTURAL PRACTICES IN THE BUREAU OF FISHERIES. 707 



FISHES OF THE GREAT LAKES. 



For the maintenance of the fisheries of the Great Lakes the Bureau operates 

 hatcheries at Put-in Bay, Ohio, Northville, Mich., Duluth, Minn., and Cape 

 Vincent, N. Y. At Cape Vincent the work consists largely in hatching and 

 distributing the product of eggs received from other hatcheries, Lake Ontario 

 not being a fruitful field for the collection of eggs. 



WHITEFISH. 



At Put-in Bay station in the fall of 1907 the collections of whitefish eggs 

 reached a total of 336,000,000, the largest on record for any station." In this 

 locality the eggs are in large part obtained by direct purchase from the fisher- 

 men, who have expelled and fertilized them as they removed the fish from the 

 nets. In addition it is customary to pen 8,000 to 10,000 fish in crates at points 

 convenient to the base of operations. These fish are obtained from fishermen 

 at a nominal price for use until after spawning, when they are returned to the 

 fishermen to be marketed. As it has not been practicable to confine the fish 

 successfully for a very long time, this procedure is not undertaken imtil they 

 are nearly ripe, the total period of confinement from the beginning of the collec- 

 tion to the close being about three weeks. 



The crates used for penning the fish are 16 feet long by 8 feet wide by 6 

 feet deep, and have a partition dividing each crate into two compartments 8 

 feet square by 6 feet deep. Each compartment is provided with a false bot-^ 

 tom, which may be raised at will while the fish are being manipulated, and can 

 be shoved down against the stationary bottom afterwards. For convenience in 

 handling the crates are made "knock down, " and thus can be easily removed 

 from the water and used year after year. While in the water they are held in 

 position by floats 52 feet long, the crates placed between them endwise, five crates 

 forming a raft. Only 12 inches of the crates extends above the surface of the 

 water. The rafts are held in place by stakes driven into the bottom of the bay. 

 Of the total number of eggs collected about 25 per cent are taken from fish con- 

 fined in crates. 



Another important field station for the collection of whitefish eggs is in the 

 Detroit River, where operations are conducted from the Northville (Mich.) sta- 

 tion. Here the eggs are derived from fish caught for fish-cultural purposes by 

 market fishermen who operate under permits issued by the Bureau. The fisher- 

 men are willing to incur all expenses of the collections, as well as the losses from 

 penning, for the privilege of disposing of all the marketable fish after the Bureau 

 has taken the eggs. Penning stations are located accessible to the seining 



"^ Since this writing another spawning season has passed with a record for the Put-in Bay station 

 of over 373,000,000 whitefish eggs. 



