ABTinCIAL PROPAGATION OF TROUT. 31 



a mile or more in length, though never more than 8 feet wide and 

 with a water depth rarely exceeding 2 feet. Where there is an 

 abundant supply of water a strong current flows through the race- 

 ways, sometimes broken at short intervals by partition boards ex- 

 tending half way from the surface of the water to the bottom, with 

 openings somewhat narrower than the raceway. The refuse swept 

 downstream by the current and the actions of the fish is deposited 

 in the eddies formed above these riffles and may be removed easily. 

 If the fish are uniform in size, no screens are placed between the 

 compartments formed by the partitions, but if different sizes are 

 carried in the same race screens form the partitions. Usually the 

 upper sections of the raceways are screened for retaining the fry 

 and the lower sections are used for holding the larger fish. As soon 

 as the fry in the hatching troughs begin to take food freely they 

 are transferred to the raceways and fed systematically. 



Wliile such packing-house products as the livers, hearts, melts, 

 and lungs of cattle, hogs, or sheep form the principal food, quan- 

 tities of small waste fish, especially small herrings, are utilized at 

 hatcheries located in the vicinity of the New England coast fisheries. 



The trout market demands fish known as " thirds," " quarters," 

 and " fifths," designations for fish running, respectively, 3, 4, and 

 5 to the pound. Many of the fish attain these sizes by the time 

 they are 20 months old, at which age they produce their first eggs. 

 After taking the spawn the fish are again placed in the raceways 

 or in special ponds or pools and fed all they will eat until they are 

 in proper condition for marketing, when they command 50 to 60 

 cents per pound, net. 



Some commercial fish culturists raise fish especially for an egg sup- 

 ply, holding them in ponds until they weigh from 2 to 3 pounds. 

 Such fish yield eggs of better quality than are usually obtained 

 from fish spawning for the first time, especially if a certain amount 

 of natural food is available in the ponds in which they are kept. 



The eggs produced in 1922 by commercial establisliments were 

 sold at from $1 to $1.50 per thousand, depending upon their quality 

 and the number contracted for. As a rule, eggs are purchased 

 subject to their condition upon receipt, and it is generally stipulated 

 that they shall be shipped as soon as they have reached the stage 

 when infertile eggs can be removed. Consignments of eggs that 

 are very near the point of hatching upon arrival at their destination 

 are likely to suffer heavy loss both in the egg and in the fry stage. 



RAINBOW TROUT.^ 



The following discussion relates to the rainbow trout, which has 

 received the attention of fish-culturists throughout the country. 

 The earliest work along this line was concerned with the rainbow 

 trout of the McCloud River and later was extended to include the 

 trout of the Klamath River basin. Subsequently eggs of the steel- 

 head from the Rogue River in Oregon and certain streams in Wash- 

 ington were shipped east, and in many instances the fish resulting 

 therefrom have been distributed in public waters under the name of 



' The notes for the section on Rainbow Trout were contributed almost entirely bv George 

 A. Seagle, superintendent of the Wytheville (Va.) station of the Bureau of Fisheries from 

 1880 to 1922, who has very ably described the methods employed at that station ia the 

 artificial propagation of this speciei. 



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