42 



Fishery Bulletin 105(1) 



Year-to-year variability was generally synchronous 

 among the three species (Fig. 2). Abundance was below 

 average for the three species in 1983-84, and 1989-98. 

 Above average abundance in all three species occurred 

 in 1985, 1987, 1988, and in 2001. Black rockfish at- 

 tained relatively greater numbers in 1986, 1999, 2000. 

 and 2003 compared to the other two species. In addition, 

 blue rockfish experienced higher than average abun- 

 dances in 2001 and 2002 compared to the other species. 

 Generally, the index for black rockfish was lower than 

 for the other two species, but black rockfish abundance 

 was extremely high in 1999, but the abundance of the 

 other two species was below average. Indices for blue 

 and yellowtail rockfish were significantly correlated 

 (P<0.001, r=0.91), and the index for black rockfish was 

 not significantly correlated with either of the other two 

 species. Using the log-transformed index, we found that 

 blue, yellowtail, and black rockfish were all significantly 

 correlated (P<0.01, r=0.76) with each other. We used the 

 log-transformed index for the remaining analyses. 



In evaluating seasonal oceanographic variables, sea 

 level anomaly and nearshore temperature were sig- 



nificantly and positively correlated (P<0.05, 7-=0.53), 

 nearshore temperature and offshore Ekman transport 

 were significantly and negatively correlated (P<0.05, 

 r=-0.69), and sea level anomaly and offshore Ekman 

 transport were not significantly correlated. There was 

 no significant correlation between the seasonal oceano- 

 graphic variables and the index for any species. 



With PCA, 65% of the variability in the monthly 

 oceanographic (q) data sets was explained by the first 

 eigenvector (PCIq). PCIq was characterized by the 

 contrast between Ekman transport and the other two 

 variables (Table 2). The second eigenvector (PC2q) ex- 

 plained 30% of the variability and was associated with 

 high sea level anomaly. For the rockfish abundance (p) 

 indices, 77% of the variability was explained in the 

 first eigenvector (PClp), which was associated with the 

 abundance time series of all three species. The second 

 eigenvector (PC2p) explained 15% of the variability and 

 was associated with the contrast between blue rockfish 

 abundance and the other two species, especially late in 

 the time series. Although PC3p explained only 8% of 

 the variability in these time series, it was associated 



