Woodbury: Reduction of growth in otoliths of Sebastes entomelas and S flavidus 



685 



i 30 - 



2,5 



though both species exhibited significant 

 reduction in otolith growth in 1983, the 

 effect was more pronounced at Bodega, 

 consistent with a decreasing effect of El 

 Nino with increasing latitude, as was ob- 

 served in Pacific hake (MacLellan and 

 Saunders, 1995). Although otolith growth 

 recovered quickly for both species at Eu- 

 reka and for yellowtail rockfish at Bodega, 

 otolith growth for widow rockfish collected 

 fi-om Bodega was relatively slow to recover. 

 Results of the principal component 

 analysis on the oceanographic data (Table 

 3) show that only the first two components 

 are very informative (eigenvalue >1; first 

 three principal components shown). Note 

 that the first component explained 107c of 

 the combined variation among all 13 

 oceanographic variables, whereas the sec- 

 ond component accounted for an additional 

 18%. As the loadings on the first principal 

 component indicate, temperature and sea 

 level anomaly are closely linked. Up- 

 welling loads higher with increasing lati- 

 tude, which may relate to increased upwelling from 

 south to north along that section of coast. Upwelling 

 also demonstrates an inverse relation with tempera- 

 ture and sea level anomaly. Finally, the atmospheric 

 pressure statistic does not contribute substantially 

 to the first principal component, although it is much 

 more influential in the second component. 



40 



35 



2,0 



Yellowtail Rockfish 

 Widow Rockfish 



85 



86 



87 



80 81 82 83 84 



Year 



Figure 5 



Mean annual otolith growth indices ( 1980-87) for each species. Bars 

 represent ±2 standard errors of the mean. 



A multiple regression of otolith growth on the first 

 two principal components showed that the second 

 component was neither significant nor informative, 

 and it was therefore dropped from the analysis. An 

 ordinary regression of otolith growth on the first prin- 

 cipal component resulted in a significant relation- 

 ship for both widow and yellowtail rockfish (P=0.033 



