PEARCY: ALBACORE OCEANOGRAPHY 



The temperature section from the inbound 

 track off Cape Lookout and Depoe Bay (Figure 

 16), made during the end of the cruise when 



CAPE LOOKOUT STATIONS 



DEPOE BAY STATIONS 



TEMPERATURE CO 



J I I \ 1 I I I L_ 



Figure 16. — Temperature section along the east-west 

 stations offshore of Cape Lookout and Depoe Bay 

 stations, inbound leg, 1 and 2 August. The Depoe Bay 

 stations are the same ones shown in Figure 15 but 6 

 days later. 



winds were blowing from the north, shows 

 more evidence for upwelling than the earlier 

 outbound track. The 15 °C isotherm intersected 

 the surface farther offshore and isotherms slope 

 more steeply nearshore. However, surface 

 temperatures are again not suggestive of strong 

 upwelling. Inshore along the Depoe Bay Sta- 

 tions, the 16° and 15°C isotherms were deeper 

 on the inbound than outbound legs, indicating 

 a deepening of the mixed layer depth during 

 the intervening time, but neither mixed layer 

 depths beyond 75 miles off the coast or the 

 depth of the 15 °C isotherm increased notice- 

 ably with time. Surface water of 16 °C was still 

 located in two areas, which is consistent with 

 the outbound leg, and facilitated the areal 

 plot of surface temperature from all data. 



Two extensions of low-salinity water ( <32"/oo) 

 are seen emanating from the Columbia River, 

 one to the south and one to the southwest of 

 the river mouth (Figure 17). These lobes of 

 low salinity correspond with the regions of 

 warmest temperature seen in Figure 14 and 

 support the premise that warm water is often 

 associated with low salinity. This correlation 

 is not apparent close to the river mouth, 

 however, because of admixture of plume with 

 cool upwelled water and insufficient time for 

 warming of the low-salinity lens. 



Light extinction coefficients, calculated from 

 photometer casts during daytime were lowest 



"f I I I I I I I M I M I I I I I I I I I I I II I I 'l I I M l '' 



^ 



■oesTRucrioM i. 



SURFACE SALINITY (7oo) 



J^4 



I I I I I I I I I i I I I I I I I I I I I I I I I I I I I 



Figure 17. — Surface salinity measured during the cruise, 

 27 July-2 August 1970. Dots indicate stations. 



offshore, increased in the region of the plume, 

 and were highest along the coast (Figure 18). 

 This agrees with Pak, Beardsley, and Park 

 (1970) who found higher concentrations of 

 light scattering particles in the low-salinity, 

 warm plume waters than offshore. 



Albacore Catches 



The catch rates of albacore by the Cayuse 

 during the cruise are shown between daylight 

 stations in Figure 19. Highest catches were 



I I I I I I I I I I II I I I 



^ 



III! 



■OeSTfhXTtON I. 



EXTINCTION COEFFICIENTS (K) 



I I I I 



M I I I I I I I I I I I 



^010 



ax 



ioefve air 



0.20 : 



I I I I I I I 111 I I I I I 



Figure 18. — Extinction coefficients of downwelling ir- 

 radiance, k = (In/o - lnl^)ld, where /o is surface 

 intensity and Ij is the intensity at depth J. Dots indicate 

 stations where photometer casts were made. 



499 



