PEOPAGATION AND DISTRIBUTION OF FOOD FISHES, 19*24 403 



including the Izaak Walton League of America, the pearl-button indus- 

 try, which is directly dependent on the supply of fresh-water mussels 

 for its raw material, and the commercial fishing interests generally. 



La Crosse (Wis.) substation. — In addition to the rescue and mussel- 

 infection work accomplished at the La Crosse (Wis.) substation, eggs 

 of the rainbow trout from Neosho (Mo.), Manchester (Iowa), and 

 White Sulphur Springs (W. Va.) stations, brook-trout eggs from a 

 commercial breeder, Loch Leven trout eggs from the Bozeman (Mont.) 

 station, and pike-perch eggs from the State of Minnesota were incu- 

 bated and the resulting fry distributed to applicants in Wisconsin 

 and Minnesota. 



Atchafalaya (La.) substation.- — The substation at Atchafalaya, La., 

 was opened early in February and the necessary arrangements made for 

 the collection of eggs of the buffalofish. The work of last season veri- 

 fies beyond a doubt that a new location must be found if success is to be 

 attained in the artificial propagation of this fish. Trouble of a 

 similar nature has been encountered each succeeding year since the 

 substation was established. 



Through the course of the work in 1924 a careful check on all 

 probable causes of the mortality was made, and there can no longer 

 be a doubt that the trouble is attributable to pollution carried in the 

 waters of the Ouachita River, which drains the southern Arkansas 

 oil fields. 



Several other possible sites were visited, two of which — Bayou 

 Grosse Tete and Bayou Plaquemine — appear to offer the essential 

 rec{uirements for successful work. The station should be moved to 

 one cf these locations before the propagation of buffalofish is taken up 

 next season. 



Active egg collections began on March 6, and though climatic 

 conditions were not at all favorable at any time during the spawning 

 season 277,512,500 eggs had been secured by March 29, which date 

 marks the close of the egg collections for the season. Repeated 

 attempts to incubate the eggs at the hatchery proved futile. Fer- 

 tilized eggs placed in the hatching jars in good condition showed a 

 small white spot at the end of 24 hours, and in 48 hours all eggs were 

 white and opaciue. Because of this unfortunate situation it was nec- 

 essary' to plant the fertilized eggs on the spawning grounds immedi- 

 ately after they were impregnated. 



MUSSEL INFECTION IN CONJUNCTION WITH THE RESCUE OF LAND- 

 LOCKED FISHQS 



[H. L. Canfield, in charge] 



Owing to the unusually small size of the fishes handled early in the 

 rescue season, the mussel work was not undertaken until larger and 

 more vigorous fishes were obtainable. As a consequence of this delay 

 the results were considerabh' curtailed as compared with last year. 

 The total number of mussel glochidia released on the gills of living 

 fishes in the course of the season amounted to 1,335,595,700, indicat- 

 ing a falling off of upward of 713,000,000. The work is conducted 

 at a minimum outlay of labor and time, the operation being performed 

 just prior to the release of the fishes from the tubs into open waters. 

 Its cost during the season of 1924 amounted to an average of .$0.0011 

 per thousand, or less than half the average of the preceding year. 



