686 



Fishery Bulletin 97(3), 1999 



and 0.030, respectively). Plots of mean annual otolith 

 growth index against the first principal component 

 score (Fig. 8) reveal the extreme conditions that pre- 

 vailed in 1983. In 1983, the lowest measurements of 

 otolith growth corresponded to the highest sea tem- 

 perature, highest positive sea level anomaly, and low- 

 est upwelling index. As previously noted, this par- 

 ticular El Niiio was one of the strongest on record 



for the east-central Pacific Ocean. Its signature was 

 noted off the California coast by high sea tempera- 

 ture at 100 m, being the warmest observed since 

 records were first kept starting in 1944 (Sharp and 

 McClain, 1993 ). A converse relationship between en- 

 hanced otolith growth and lower sea temperature, 

 lower sea level anomaly, and higher upwelling index 

 is not as evident, although above normal growth did 

 occur in 1985, which was the "coldest" year. 



4.0 



3.5 



P 30 



2.5 



2.0 



Yellowtail rockfish 



-^ 



widow rockfish 



12 3 4 



Age (yr) 



Figure 6 



Mean otolith growth indices at age for widow and yellowtail rockfish. 

 Bars represent ±2 standard errors of the mean. 



4,5 



4.0 



s 3.5 



% 



g 



I 3,0 

 o 



2,5 



2,0 



Eureka yellowtail rockfish 

 Cordell Bank yellowtail rockfish 

 Eureka widow rockfish 

 Bodega Bay widow rockfish 



80 



81 



82 



83 84 



Year 



85 



86 



87 



Figure 7 



Mean annual otolith growth indices (1980-87) for widow and yellow- 

 tail rockfish from two geographic areas. Bars represent ±2 standard 

 errors of the mean. 



Discussion 



In this paper, the reduction in growth of 

 widow and yellowtail rockfish otoliths dur- 

 ing 1983 was quantified by measuring an- 

 nuli surface areas. Otolith growth is pos- 

 tulated to represent a conservative mea- 

 sure of somatic growth. Casselman ( 1990) 

 determined that otoliths from several spe- 

 cies of freshwater fish grew relatively faster 

 than their body during periods of slow body 

 growth. Francis et al. (1993) argue that 

 otolith growth in Pagrus auratus can occur 

 even if somatic growth has stopped. There- 

 fore, the reduction observed fi-om this study 

 may indicate an even larger reduction in 

 somatic growth, perhaps affecting reproduc- 

 tive capacity as well. This was observed by 

 VenTresca et al. (1995) who noted a reduc- 

 tion in both the somatic and gonadal indices 

 of blue rockfish (S. mystinus) inhabiting 

 California coastal waters in 1983. 



It appears that the oceanographic per- 

 turbations caused by El Niiio had a nega- 

 tive effect on the growth of these fish. Tem- 

 perature has been implicated as a major 

 contributor to influencing both otolith and 

 somatic growth. Lombarte and Lleonart 

 (1993) stated that environmental condi- 

 tions, mainly temperature, regulate the 

 quantity of material deposited during the 

 formation of the otoliths. Dorn (1992) 

 found that growth of Pacific whiting 

 (Merluccius productus), which inhabit 

 similar waters, is most affected by tem- 

 perature during younger ages. 



Although physical oceanographic condi- 

 tions and otolith growth were found to be 

 significantly correlated, the causal rela- 

 tionship may well be based on preferred 

 food availability. Central California repre- 

 sents the southernmost range of both 

 widow and yellowtail rockfish. Pearson 

 and Hightower (1991) reported slower 



