FISHERY BULLETIN: VOL. 76, NO. 3 



124° 



rAQUIMA 

 BAY 



Figure l. — Locations of the seven sta- 

 tions (numbered) off the central Oregon 

 continental shelf that were selected for 

 this study. 



types are diverse and do not necessarily grade 

 regularly from coarse sand on the inner shelf to 

 finer sediments with increased depth (Kulm et al. 

 1975). Because of this heterogenous distribution of 

 sediments, a natural experiment can be designed 

 to differentiate between possible effects of depth 

 and sediment type. Seven stations were selected in 

 an attempt to provide different sediment types at 

 the same depth and the same sediment types at 

 different depths. The region inshore of Heceta 

 Bank produces large commercial catches of 

 flatfishes, such as Dover sole, rex sole, English 

 sole, and Pacific sanddab (Demory et al.^). 



METHODS 



The sediment types for the stations were charac- 

 terized by the percent sand, silt, and clay, percent 

 of organic carbon and median particle size by Ber- 

 trand (1971) and Gunther (1972) (Table 1). A 

 Phleger multiple corer was used to sample sedi- 

 ments. Initially sediments were sampled at the 

 apices of a triangle (sides = 1 n.mi.) and at each 



^Demory, R. L., M. J. Hosie, N. Ten Eyck, and B. O. 

 Forsberg. 1976. Marine resource surveys on the continental 

 shelf off Oregon, 1971-74. Oreg. Dep. Fish Wildl. Rep., 49 p. 



630 



