716 



Fishery Bulletin 93(4), 1995 



served in nearshore habitats in August-Sep- 

 tember (Fig. 4). For blue rockfish and yellow- 

 tail rockfish, it is apparent that the abundance 

 of young-of-the-year juveniles was lowest when 

 winter SSTs were highest, as for example in 

 1983 and 1992. Both years were distinguished 

 by strong El Nino events (Wooster and 

 Fluharty, 1985; Hayward, 1993). There was 

 also the suggestion that cold winter SST's may 

 have adversely impacted survival of these rock- 

 fish to the juvenile stage, as evidenced by the 

 data for 1989 and 1990. Conversely, increased 

 numbers of juveniles occurred in years when 

 SST was intermediate, especially in 1987 and 

 1988. Overall, these findings are consistent 

 with a dome-shaped relationship between lar- 

 val survival and winter temperature. 



Discussion 



Biological synchrony and 

 oceanographic scale 



Our results show a broad spatial coherence 

 in the temporal abundance patterns of young- 

 of-the-year juvenile rockfish. The trawl study 

 area is separated from Sonoma and Mendo- 

 cino Counties by distances of 50-350 km (Fig. 1); yet 

 interannual fluctuations in the abundance of blue 

 and yellowtail rockfish at these sites are closely 

 linked (Figs. 2 and 3). Even so, had there been closer 

 spatial overlap between the trawl and nearshore 

 study areas, the correlations probably would have 

 been even higher. For example, our highest correla- 

 tions between the annual abundance indices of pe- 

 lagic and settled juveniles (0.861 and 0.799, Fig. 3) 

 were for Sonoma County, the closer of the two 

 nearshore sites to the trawl survey area. 



Not only was there broad spatial agreement in the 

 trends of blue and yellowtail rockfish, abundances 

 of these species were highly correlated with one an- 

 other. Strong and weak years closely mirrored each 

 other over the 10-year study period (Fig. 2). Other 

 studies have shown marked interannual synchrony 

 among species of pelagic juvenile rockfish, in terms 

 of growth rates and birthdate distributions (Wood- 

 bury and Ralston, 1991) as well as shifts in dietary 

 composition (Reilly et al., 1992). These findings in- 

 dicate that large-scale oceanographic processes are 

 primarily responsible for the extensive interannual 

 fluctuations in the abundance of young-of-the-year 

 juvenile rockfishes. 



This conclusion is in agreement with results from 

 Hollowed et al. (1987), who showed extensive inter- 



