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Fishery Bulletin 89(3), 1991 



ence (calendar date of capture minus age in days), and 

 (4) aggregating the data into frequency distributions. 

 Although with this approach some lengths were ex- 

 cluded, data from April cruises were not used due to 

 the sporadic sampling (temporally and spatially) that 

 occurred. Back-calculated birthdate distributions were 

 compared within and among years, as well as among 

 species. 



Results 



In some cases, analysis of covariance (ANCOVA) re- 

 vealed statistically significant differences in the rela- 

 tionship of standard length and age among the various 

 sweeps conducted within a year (i.e., bocaccio in 1987, 

 chilipepper in 1988, widow rockfish in 1987, and yellow- 

 tail rockfish in 1986). It is notable, however, that these 

 cases represented only 4 of the 15 species-year com- 

 binations for which data were available. Further ex- 

 amination of the data revealed that in one of these 

 cases significance was due to a very small sample 

 obtained during one sweep. Moreover, in the other 

 three instances there was no regular pattern of either 

 increasing or decreasing growth rate as the season 

 progressed and the magnitude of differ- 

 ences was small. For these reasons a 

 single regression equation describing the 

 annual growth of each species was gen- 

 erated by pooling the age data obtained 

 in a year, ignoring the sweep of origin. 



Growth 



Shortbelly rockfish There was a linear 

 relationship between standard length 

 (mm) and age (days) for shortbelly rock- 

 fish over the size range collected in each 

 year during 1983-88 (Fig. 2). A simple 

 linear growth model was fit to each year 

 individually (Table 2). Annual estimates 

 of pelagic juvenile shortbelly rockfish 

 growth rate ranged from 0.524 mm/day 

 in 1985 to 0.638mm/day in 1983. Results 

 from ANCOVA (Table 3) showed that 

 significant differences (P 0.019) occurred 

 in annual growth rates (i.e., slopes) 

 among the six years sampled. Growth 

 rates were relatively low in 1985 and 

 1986, were medium in 1984 and 1988, 

 and were high in 1983 and 1987. To test 

 for differences in estimates of annual 

 growth rate, pairwise comparisons were 

 made using LSD tests (Fig. 3). 



