388 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



DESCRIPTION OF THE UNITED STATES FISH II \ I < II I !? V AT AL- 

 PENA, 'IHIIK. W 



By FRANK \. CLARK. 



[Written by request of Prof. S. F. Baird, for the London Exhibition, 1883.] 



This hatchery was built in the fall of 1882. It is a one-story frame 

 building, 30 feet wide by 60 feet long, having front and rear entrances, 

 and amply lighted by fourteen windows. The main floor includes the 

 hatching room, and au office and sleeping apartment 10 feet wide by 18 

 long. The space between this office and the opposite side is conven- 

 iently utilized for storage of tools, cans, egg-cases, &c. The hatchery 

 is arranged and equipped with especial reference to the manipulation 

 of the embryos and minnows of white-fish (Coregonus clupeiformis), the 

 most valuable commercial species of the Great Lakes. Its nominal 

 capacity is 100,000,000 eggs. 



The water is furnished by the Holly Water Works Company, of 

 Alpena, being forced through wooden mains from Thunder Bay, an arm 

 of Lake Huron. A 2-inch stream, under an average pressure of 20 

 pounds to the square inch, connects with the hatchery, the discharge 

 being regulated by globe valves and ball cocks. The inlet pipe is laid 

 underneath the building, near the front, and is tapped by four perpen- 

 dicular arms, each dicharging into the top tank of one of the four sys'tems 

 of tanks for supplying water to the hatching apparatus. Each system 

 comprises a series of four rows of tanks, one row above the other. 

 There are two tanks to each row, making eight tanks in the series, or 

 thirty-two in all, each of which is 15 feet long by 12 inches wide, and 10 

 inches deep. One series is the exact counterpart of another. A row 

 of faucets on either side of the top tank, into which the water first 

 enters, supplies two rows of hatching jars, or incubators, which stand 

 on shelves placed across the second tank below and discharge into the 

 tank between, which, in turn, feeds a second scries of jars, and so on. 

 In this way the four rows of a series operate three double rows of jars, 

 the water being used three times over. Overflows arc provided at the 

 ends of the tanks, which discharge into the next below. 



Each of these series of reservoirs is connected with larger tanks, into 

 which the minnows are carried by the current as soon as hatched. 



The outflow openings of the tanks for the reception of the minnows 

 are protected by finely perforated tin boxes of sufficient dimensions to 

 keep the little fish away from the vortex formed by. the escaping fluid, 

 where they would be liable to injury from the strong current. There 

 are ten of these receiving tanks, with an aggregate capacity of 7,000 

 gallons. 



