FISHERY BULLETIN: VOL. 71, NO. 2 



this plot thus estimates the central location 

 of the tleet. 



The first albacore of the 1970 season off 

 Oregon were caught between Newport and 

 Coos Bay on 15 July, and the subsequent 

 early fishery during 15-21 July was localized 

 about 140 miles off the central and southern 

 Oregon coast. Boats shifted rapidly northward 

 during 20-22 July and then were localized 

 about 100 miles off the Columbia River during 

 22-29 July. (An exception was 25 July, when 

 most boats moved south about 50-60 miles.) 

 Between 29 and 31 July, during the major 

 decline of the fishery, boats moved inshore 

 to within 60 miles of the mouth of the Columbia 

 River. This was followed by a shift to the 

 south in early August and then an additional 

 inshore movement to within 30 miles off the 

 central coast. After 4 August the number of 

 jig boats reporting catches was less than 11 

 and positions are not noted in Figure 2. 



Thus the jig fishery off Oregon moved north- 

 ward during July and became localized in 

 the region off the Columbia River, where most 

 of the fish were caught during the 1970 season. 

 During the rapid decline of catches, jig boats 

 moved inshore and to the south. Fishermen 

 say that such an inshore movement of albacore 

 may occur late in the season (September- 

 October) when fish apparently form dense 

 schools closer to shore and are often difficult 

 to catch on trolled jigs. The bait boat fishery 

 for albacore usually peaks late in the season, 

 after jig catches decline (R. M. Laurs, pers. 

 comm.). Thus both the inshore movement of 

 the jig fishery and the good bait fishery oc- 

 curred anomalously early in 1970. 



1970 albacore season. North-south and east- 

 west components of winds are given in Figure 

 3 to aid in interpretation of wind-driven ocean 

 circulation. 



Figure 3. — Componenls of average daily wind velocities 

 recorded at Newport. Oreg. 



Cruise — 7-10 July 



Results of this preseason albacore cruise, off 

 northern and central Oregon (Figure 4), illus- 

 trate the influence of both upwelling and 



I I I I I 



I I I I I 



20 19 la 17 1615 H 



26 27 28 29 30 31 32 33 34 



I I I 'I I I I M I I I I' I I I I I I 



OCEANOGRAPHIC CONDITIONS 



In hopes of learning more about oceanogra- 

 phic conditions off Oregon and how changes in 

 catches are related to upwelling and the Colum- 

 bia River plume, we conducted weekly aircraft 

 flights to obtain data on sea-surface tempera- 

 ture using infrared radiometers and fielded 

 several cruises to determine ocean conditions 

 both before the albacore season and later in 

 the area of the albacore fleet. This section 

 summarizes ocean features found during the 



Figure 4. — Location of STD (Salinity-Temperature- 

 Depth probe) stations during the preseason albacore 

 cruise, 7-10 July 1970. (Cayusc 1001 A). 



Columbia River plume on the ocean environ- 

 ment. Isolines of salinity and temperature in 

 the east-west sections (off the Columbia River 

 and Newport, Figure 5a, b, e, f) slope upwards 

 towards shore and are indicative of upwelling, 

 the replacement of near-surface waters with 

 deeper, saline, low-temperature water. The 

 low-salinity waters of the Columbia River 

 plume are evident in all sections. Plume 



492 



