United States Department of the Interior, Douglas McKay, Secretary 

 Fish and Wildlife Service, John L. Farley, Director 



BIOLOGICAL EFFECTS ON HARD CLALB 

 OF HAND RA.KING AND POIVER DREDGITJG 



By 



John B. Glude and Warren 3, Landers 

 Fishery Research Biologists 



Special Scientific Report: Fisheries 110 



Washington, D. G. 

 October 1953 



