XXVI KEPORT TO THE SECRETARY OF COMMERCE 



Numerous experiments made with different toxic substances have 

 shown that jjositive results could be expected only with various 

 copper salts. 



In cooperation with the State department of fisheries there has 

 been established at Olympia, Wash., a laboratory adapted for re- 

 Fearch on problems of the oyster industry of Puget Sound. An 

 investigation of the effect of pulp-mill wastes on oysters, which has 

 been carried on since 1929, has been completed and the report is in 

 press. Present investigations deal primarily with the methods of 

 cultivation and the biology of the native oyster. An investigator 

 also was stationed on the Oregon coast to study local problems and 

 to assist in developing improved practices in oyster culture. 



Investigations of fresh-water pearl mussels, which provide raw 

 material for the great American button industry, were conducted 

 from laboratory headquarters at the University of Missouri and at 

 various places along the Mississippi River and its tributaries from a 

 floating laboratory loaned by the United States Army engineers and 

 later purchased from them. These investigations are primarily 

 aimed at the perfection of new methods of mussel culture devised in 

 previous years' studies to propagate fresh-water mussels by means 

 independent from fishes of the locality, which in nature must serve 

 as hosts during the parasitic stage of the development of mussel 

 larvae. Immediate adoption of this method of culture on a com- 

 mercial scale is prevented by the existence of sufficient pollution from 

 industrial and domestic sources in the entire upper Mississippi River 

 and in many of its tributaries to kill the young mussels. Accord- 

 ingly, a critical study of this pollution factor has also been under- 

 taken. 



Surveys of other river systems, including those of Texas flowing 

 directly into the Gulf of Mexico, have resulted in discoveries of con- 

 siderable areas of river bottoms suitable for the propagation of 

 mussels. A further survey is being organized to study the Missis- 

 sippi River conditions south of Keokuk Dam and along the Ohio and 

 Tennessee Rivers. In the course of this expedition with the floating 

 laboratory, quantities of mussel spawn will be propagated and 

 planted as suitable water areas are encountered. Plans have also 

 been made to establish a mussel-rearing station at the bureau's 

 fish hatchery at Fort Worth, Tex., for the stocking of waters in that 

 region. 



The War Department's program calling for the construction of a 

 score of dams and a 9-foot ship channel in the upper half of the river 

 has aroused the fears and protests of fishermen and sportsmen 

 throughout the region. At the request of the War Department, 

 therefore, the bureau undertook a survey of the area involved in 

 order to ascertain what would be the probable effects upon the fish 

 and mussel fauna of the canal and water storage projects. A detailed 

 limnological survey was completed early in the fiscal year and a 

 preliminary report was presented to the War Department summariz- 

 ing the findings. This report pointed out that if pollution and silt- 

 ing of the river were first corrected, the canalization project would 

 not be harmful, and indeed might be beneficial to fish life in that 

 area. 



