PROPAGATION" AND DISTRIBUTION OF FOOD FISHES, 1926 355 



arrival, but the fry hatched from them were afflicted with a disease known as 

 "blue sac," and nearly all of them perished. Other shipments of brook, rain- 

 bow, and Loch Leven trout eggs were received in hue condition, and the 

 resulting fry were strong and healthy. 



Homer {Minn.) substation.- — Fish-cultural operations at this station consist 

 almost exclusively in the rescue of landlocked fishes from overflowed lands 

 along the Mississippi River and the inoculation of considerable numbers of 

 them with the larvae of the commercial mussels. Game fishes also are held here 

 for later distribution, the station having pond capacity for about 2% carloads. 

 During the early part of the rescue season the water level in the river was at 

 a favorable point, but it receded later, and had it not been for frequent rains 

 many of the pools would have become dry before the fish contained in them 

 could be salvaged. Work was prosecuted under such conditions until October, 

 when the operations were considerably checked by cold weather and heavy 

 rains. 



Bellevue (Iowa) substation. — Notwithstanding the fact that the water level 

 at this point was not favorable for rescue work and only one crew of men was 

 employed, the season's results were very satisfactory, the number of fish sal- 

 vaged being 100 per cent larger than in the preceding year. 



Marquette (Iowa) substation. — Rescue work at this substation is prosecuted 

 in connection with similar operations conducted at Guttenberg, Iowa. The 

 field is advantageously located for the distribution of fish, and its output 

 compares very favorably with that at other collecting points. 



Atchafalaya (La.) substation. — Because of the large amount of pollution 

 carried in the water from Ouachita River, which supply was used at the 

 hatchery site formerly occupied in the propagation of buffalo fish in the 

 Louisiana field, the old location was abandoned and a new hatchery erected 

 during the year on the Bayou Plaquemine, where a water supply of good 

 quality is accessible. The material for the new hatchery, which is 20 feet 

 by 75 feet in dimensions, was provided by the Louisiana Conservation Commis- 

 sion, while the work of constructing it was done by the bureau's force in 

 connection with their regular fish-cultural duties. During the spawning 

 season of the buffalo fish (from February 26 to April 1) 128.100.000 eggs of 

 fine quality were obtained. These were incubated successfully and produced 

 105,315.000 fry, which were planted on the native spawning grounds. 



Mussel Infection in Conjunction with the Rescue of Landlockeo Fishes 



Mussel-infection operations were conducted as heretofore in con- 

 nection with the salvage of food fishes from overflowed lands along 

 the Mississippi River. The work assumed extensive proportions 

 and resulted in the release of 2,803,653,100 larval mussels on the 

 gills of suitable fishes, at an average cost of only $0.00144 per thou- 

 sand. Much valuable cooperative assistance was rendered by clam 

 fishermen and others engaged in the industry, while many letters 

 commending the work were received from clam and pearl dealers 

 and pearl-button manufacturers. The fields in which mussel- 

 infection operations were conducted during the year and the num- 

 bers and species of mussels handled in each are shown in the 

 following table ; 



