Allen and Franklin: Settlement patterns of Atractoscion nobilis in the Southern California Bight 



639 



significant, furtiier emphasizing the inshore-offshore 

 distribution pattern of white seabass settlement. 



Temperature Bottom temperature ranked second 

 among environmental variables in its correlation to 

 CPUE over both years, although the correlation of 

 0.10 was not statistically significant (Table 2). The lack 

 of significance may be due to the fact that the rela- 

 tionship of catch to temperature differed noticeably 

 in the 2 years and that overall catches were lower in 

 1989. 



In 1988, the heaviest and most widespread settle- 

 ment of YOY coincided with the striking rise in coastal 

 temperature during July in the study area, resulting 

 in a significant correlation between log-transformed 

 [logio (x-i- 1)] abundance of YOY and bottom temper- 

 ature (rO.25, P<0.05, 74df). In 1989, however, the 

 greatest and most widespread YOY abundance was en- 

 countered in June when temperatures were generally 

 depressed. Thus the peak settlement in 1989 occurred 

 1 month earlier than in 1988 and was apparently not 

 as closely related to a rise in sea temperature as it 

 seemed to be in 1988. 



Biomass of drift algae Samples of submerged drift 

 algae ranged from trace amounts (<50g) to > 500 kg 

 per tow for each depth and station. No significant cor- 

 relation (r 0.036; Table 2) was found between the 

 weight of drift algae and the abundance of young white 

 seabass. However, only two fish (both >60mmSL) 

 were captured without drift algae in the nets. Thus, 

 drift algae and YOY white seabass may be related on 

 a presence/absence rather than a quantitative basis. 

 Correlations of catch with other physicochemical 

 variables were too low to warrant consideration. 



Multivariate model A combination of three environ- 

 mental variables— distance from the mainland, bottom 

 temperature, and biomass of drift algae— produced a 

 significant canonical correlation with CPUE (Table 3). 

 Though significant, the correlation accounted for only 

 5% (R- 0.052) of the variation in CPUE. A significant 

 canonical correlation with distance and bottom tem- 

 perature alone accounted for slightly less variation in 

 CPUE (R- 0.051). 



Discussion 



Density estimates for white seabass off the coast of 

 southern California were low. Population estimates 

 based on these densities for the Southern California 

 Bight were only 130,000 and 118,000 individuals in 

 1988 and 1989, respectively. The lower value in 1989 

 is not surprising since catches at the island stations 

 were extremely low (a high of five YOY at Santa 

 Cruz I., and none at Santa Rosa and San Clemente Is.). 

 Even if these estimates are assumed to be within an 

 order of magnitude of the real population levels, it is 

 obvious that settlement of white seabass was poor in 

 southern California waters. Our data showing relative- 

 ly low numbers of YOY white seabass in southern 

 California for both sampling years present a similar pic- 

 ture to that presented in Moser et al. (1983) for larval 

 white seabass. The major settlement areas for this 

 species undoubtedly occur to the south in Mexican 

 waters. 



Catches of YOY white seabass were highly variable 

 in space and time. Only a small portion of this variabil- 

 ity was explained by the environmental variables 

 measured. Monthly differences in catch were marked 



