490 



Fishery Bulletin 92(3), 1994 



Table 3 



Regressions of year-class strength (YCS) for petrale sole, Eopsetta jordani (thousands of females attaining age 6), on 

 environmental anomalies in Pacific States Marine Fisheries Commission areas 2B and 3A from 1958 to 1977. Environ- 

 mental anomalies are based on the long-term mean 1958-77. SST = sea surface temperature anomaly (Dec.-Feb.), SL = 

 mean sea level height anomaly (Dec.-Feb. ), Me = offshore Ekman transport anomaly ( Jan.-Mar. ). P<0.05 for significant corre- 

 lations (n = 20 years I. In the last regression model, R 2 = 0.667 between predicted YCS (e ln<YCSl ) and YCS index (P<0.05). 



Area Regression model 



Fl- 



YCS on SST 



3A YCS = 524.5048 + 104.8226 SST 



YCS on SST and SST 2 

 3A YCS = 550.4459 + 116.8338 SST - 44.9699 SST 2 



YCS on Me and Me 2 



2B YCS = 357.0224 - 2.9121 Me - 0.0340 Me 2 



3A YCS = 576.0152 - 4.3035 Me - 0.0391 Me 2 



YCS on SL and SL 2 



2B YCS = 347.0157 + 625.3314 SL - 8103.1487 SL 2 



3A YCS = 565.1595 + 1686.4019 SL - 8512.4524 SL 2 



YCS on Me, Me 2 , SL and SL 2 



2B YCS = 377.9325 - 2.3712 Me - 0.0255 Me 2 + 346.4281 SL -7477.8599 SL 2 



3A YCS = 608.3490 - 3.8546 Me - 0.0378 Me 2 + 1104.2691 SL -7115.5843 SL 2 



Ln (YCS) on Me, Me 2 , SL, SL 2 , SST and SST 2 

 3A Ln (YCS) = 6.4115 - 0.0068 Me - 6x10-5 Me 2 + 1.9585 SL -9.0066 SL 2 



+ 0.1069 SST -0.1321 SST 2 



0.648 



<0.05 



* Nonsignificant. 



x 



UJ 



D 



2 



fl 



O (0 



Z \L 



hi u. 



= 



05 W 



n 



DC E 



c 

 _i 



7 

 6 5 



6 

 5.5 

 50 

 4.5 



7 5 

 7 

 6 5 

 b 

 5 5 



AREA 2B 



- — YCS INDEX 

 -•- - PREDICTED YCS 



V 



K-rJ 



V 



AREA 3A 



-~* — YCS INDEX 

 -«»- - PREDICTED YCS 



V*-v 



r 





56 58 60 62 64 66 68 70 72 74 76 78 

 YEAR-CLASS (1958-1977) 



Figure 1 3 



Log-transformed estimated and predicted year-class 

 strength for petrale sole, Eopsettajordani, in Pacific 

 States Marine Fisheries Commission areas 2B and 

 3A. Area 2B: prediction is based on anomalies of off- 

 shore Ekman transport and sea level height and their 

 attendant squared values. Area 3A: predicted val- 

 ues are based on anomalies of offshore Ekman trans- 

 port, sea level height, sea surface temperature, and 

 their attendant squared values. (Regression param- 

 eters are shown in Table 3.) 



species' distribution in warmer years (Cushing, 1982; 

 Bailey and Incze, 1985; Frank, 1991). 



The interrelation among oceanographic factors (e.g. 

 Huyer, 1977; Kruse and Huyer, 1983) makes it diffi- 

 cult to determine the importance of any single envi- 

 ronmental factor to YCS variation. Hence, the more 

 consistent negative correlation between YCS and off- 

 shore Ekman transport in Area 3A than in Area 2B 

 could be due in part to a higher correlation between 

 YCS and sea surface temperature in Area 3A. 



Primary production and usable solar radiation 

 seem to be positively correlated during winter and 

 spring off Oregon (Small et al., 1972). However, no 

 associations between YCS of petrale sole and mean 

 usable radiation were observed from solar radiation 

 estimates for winter or spring near areas 2B H and 

 3A 9 (Castillo, unpubl. data). On the other hand, al- 

 though a nearly tenfold increase in zooplankton pro- 

 duction from winter to summer may be stimulated 

 by coastal upwelling off Oregon (Peterson and Miller, 

 1977), correlations between YCS of petrale sole and 

 spring or summer upwelling indices did not suggest 

 that recruitment strength is primarily controlled by 



8 U.S. Weather Bureau. 1961-1964. Local climatological data, 

 Medford, Municipal Airport, Oregon, U.S. Dep. Commerce. 

 USCOMM-WB-Asheville. 



9 U.S. Weather Bureau. 1958-1964. Local climatological data, 

 Clatsop Countv Airport. Astoria, Oregon, U.S. Dep. Commerce. 

 USCOMM-WB-Asheville. 



