,64 U. S. BUREAU OF FISHERIES 



and various treatments in common use were then administered to 

 determine their rehitive vahie. In most cases the treatments failed 

 to produce tlie beneficial effects commonly ascribed to them. Com- 

 mon salt and the use of a malachite green solution at a concentra- 

 tion of 1,400,€00 for 1 hour were more efficacious than other methods 

 tried but even these were not effective in checking the disease. Un- 

 fortunately, all ex]5eriments had to be terminated early in October 

 owing to the annual egg-taking activities at the station. 



Considerable attention has been devoted to a myxosporidian para- 

 site Henneguya mhnvmcola- Ward, which infests the pink and silver 

 salmon of the Pacific coast. This parasite forms white cysts in the 

 l)ody muscles which, Avhen abundant, give rise to tlie condition known 

 locally as "tapioca." In some sections of Alaska a considerable per- 

 centage of the pink salmon may be infected with this parasite. 



A disease caused by a myxosporidian parasite of the genus Myx- 

 oboluH was found among bass fingerlings and brood fish at the Bu- 

 reau's station at Miles City, Mont. It is claimed that the infection 

 has been gradually increasing, its occurrence being estimated at 20 

 percent this year. The lesions appear as conspicuous lumps on the 

 l^ack and tail of infected fish. Since Myxosporidia require no inter- 

 mediate host for completion of the life cycle it is feared the distribu- 

 tion of bass fingerlings from the Miles City station will result in 

 widespread dissemination of the parasite. Studies on the parasite are 

 being continued in the hope of developing some practical method of 

 control. 



The Disease Service maintained for assisting State, Federal, and 

 private fish culturists in the solution of tlieir disease problems has 

 increased in popularity. Over 200 shipments of preserved specimens 

 were sent to the Seattle laboratory for diagnosis and a large number 

 of shipments were also received at the Washington laboratory. 



INVESTIGATIONS IN INTERIOR WATERS 



Dr. M. M. Ellis, in clxnrge 

 POLLUTION STUDIES 



Over 150 new localities have been investigated in the course of 

 the stream pollution studies made by the staff of the Columbia, Mo., 

 unit during the past year, and observations have been continued at 

 some 70 old stations. The routine analyses and bioassays required 

 to test and standardize the effluents and samples collected have oc- 

 cupied the time of five laboratory workers under the direction of an 

 aquatic ])hysiologist throughout the year. The combined data from 

 these field and laboratory studies of pollution and polluting sub- 

 stances have been applied to fisheries problems in three ways. I'sing 

 these data as a scientific background 43 major cases of stream pollu- 

 tion in North Carolina, South Carolina, Delaware, Virginia, Missis- 

 sippi, Alabama, Louisiana, Texas. California, Oregon, Washington, 

 Idaho, Montana, South Dakota, and New York, have been investi- 

 gated this year by field parties from the Columbia, Mo., unit and 

 reports have been pre]3ared, or are in the process of preparation, 

 for the guidance of officials and industries involved; over 200 an- 

 swers to queries from State officials, manufacturers and otliers in- 



