76 U. S. BUREAU OF FISHERIES. 



An alum-droppin<i: device was placed near the spring and a dosage 

 of 1 grain of alum to each 2^ gallons of spring water was supplied 

 to the settling tank. This rate of feed equals 1 part of alum to 

 124,000 parts of water, and since the untreated spring water entered 

 the settling tank at the rate of 80 gallons per minute it required ap- 

 l)roximately 8 pounds of alum per 24 hours. The untreated spring 

 Avater was so turbid that fingerling fish could not be seen in the 

 troughs, but the treated Avater entered the hatchery as clear as crystal. 

 The untreated spring water contains sufficient alkali in solution to 

 react completely with the small amount of sulphate of alumina neces- 

 sary to remove impurities, leaving sufficient alkaline nitrate to pre- 

 vent any " aftercoagulation " in the filtered water. A practical test 

 has been made of this system, and sufficient water was filtered to 

 supply 350,000 fingerling trout No. 2. Since it clears the water, no 

 matter how turbid, it is oelieved that brook trout can now be raised 

 successfully at the station. 



A device, believed to be unique, for cleaning the sand used as the 

 filtering element was also tried out successfully. It consists of a 

 spiked tooth rake, which may be drawn back and forth through the 

 sand by means of a windlass sprocket wheel and chain. The flow 

 of water in the sand bed of the filter is reversed during the cleaning 

 process and is discharged into the waste ditch by opening a valve. 



POND FISH-CULTURAL STATIONS. 



The work of the remaining group of stations, seven in number, was 

 concerned with the propagation of the so-called warm-water pond 

 fishes. The aggregate output of such fishes from these stations dur- 

 ing the year amounted to 2,702,480 fry and fingerlings, as compared 

 with 2,473,711 in 1921 and 1,837,508 in 1920. Though the increases 

 noted in the production of such fishes are of interest, indicating, to 

 some extent at least, the application of improved fish-cultural 

 methods as a result of the knowledge gained from past experience 

 and from special investigations, such increases are by no means ade- 

 quate to meet the pressing needs for a larger output of the species 

 involved. For a long time the bureau has found it very difficult to 

 honor requests for the pond fishes with j^romptness because of the 

 limitations imposed by natural conditions on their culture. This 

 difficulty has assumed larger proportions with the constantly increas- 

 ing interest in fish culture and the increased demands for fish for 

 stocking barren or newly formed bodies of water or for the restock- 

 ing of such waters as have, for various reasons, become depleted of 

 their indigenous fish life. At present all fish of this class that can 

 be produced with the existing facilities are assigned from one to one 

 and one-half years in advance, and it is only in rare instances that 

 requests for the pond fishes can be honored during the fiscal year in 

 which they are submitted. Some means for an increased output of 

 the pond fishes continue to be an urgent requirement of the fish- 

 cultural division. 



COLD SPRINGS (GA.) STATION. 

 [Chaeles A. Bullock, Superintendent.] 



The year's output from this station comprised 213,910 fry and 

 fingerling fish, as follows: 118,185 large-mouthed black bass, 87,200 



