Figure 17.— Surface temperature ("C.) , fall 1963. (The 183- and 1,829-m. depth contours are 

 shown.) 



lowed the configuration of the isohalines or 

 isotherms, but were inclined generally upward 

 toward shore. The rise reflected lower oxygen 

 values near shore during spring and fall; 

 minor inversions of dissolved oxygen were 

 more frequent during fall, just below the bot- 

 tom of the halocline near 200 m. A plot of dis- 

 solved oxygen at 200 m. during the fall (fig. 

 20) showed that this band of low oxygen 

 concentration (< .20 mg. at./l.) was continu- 

 ous along the entire coast over the Continental 

 Slope and closely followed the high-salinitv 

 ridge (fig. 13). 



Comparison of fall conditions with those 

 over the Continental Slope during the preceding 

 spring indicated that oxygen values at 200 m. 

 had decreased on the average, by about 0.05 



mg.at. 1. If we assume that the seasonal 

 change in biological utilization of dissolved 

 oxygen was negligible, this decrease in dissolv- 

 ed oxygen concentration corroborates the 

 change in water-mass characteristics between 

 spring and fall previously indicated by the 

 increase in temperature and salinity at 200 m. 

 off the coast of Washington. 



CONDITIONS NEAR THE BOTTOM 



To determine changes in salinity, tempera- 

 ture, and dissolved-oxygen concentrations at a 

 particular depth close to the sea floor along the 

 continental terrace, samples were obtained as 

 near the bottom as feasible — 55 m., 183 m., 914 

 m., and 1,829 m. along each of the nine lines 

 normal to shore. At the 55-m. and 183-m. sta- 



240 



U.S. FISH AND WILDLIFE SERVICE 



