FISHERY BULLETIN: VOL. 75, NO. 2 



TABLE 7. — Estimates of parameters describing the age-length 

 relationship for yellowtail rockfish, canary rockfish, and black 

 rockfish based on two independent readings of their otoliths. 

 The 95% confidence limits for the estimates are in parentheses. 

 Parameters First reading Second reading 



This difference exists because the first reading 

 was generally lower than the second, and read- 

 ability decreased with age. Interval estimates of 

 the von Bertalanffy constants L x , k, and t for first 

 and second readings for males are comparable 

 (Table 7). Greater differences occur between 

 estimates of the parameters for first and second 

 readings for females, although interval estimates 

 still overlap. For males and females for the first 

 reading, there is no overlap of interval estimates 

 for L x , slight overlap for k, and considerable 

 overlap for t (Table 7). Similarly, for males and 

 females for the second reading, there is no overlap 

 of interval estimates for L x , and considerable 

 overlap of interval estimates for k and t . This 

 indicates that differences in growth exist. 



Growth curves for male black rockfish derived 

 from two otolith readings are similar (Figure 8), 

 although discrepancies existed between fitted 

 lengths at older ages. The same is true for the age- 

 length relationship for females (Figure 8). Inter- 

 val estimates of all three von Bertalanffy con- 



5 7 9 II 13 15 17 19 21 



ESTIMATED AGE (yr) 



FIGURE 6 — Age-length relationships for yellowtail rockfish 

 derived from two independent readings of their otoliths collected 

 from Oregon samples, 1973-74. 



2 4 6 8 10 12 14 16 18 20 22 24 



ESTIMATED AGE (yr) 



FIGURE 7. — Age-length relationships for canary rockfish de- 

 rived from two independent readings of their otoliths collected 

 from Oregon samples, 1972 and 1974. 



stants overlap considerably (Table 7), indicating 

 no significant differences between growth curves 

 obtained from the two readings. For males and 

 females for the first reading, there is no overlap of 

 interval estimates for L x and k, and considerable 

 overlap for to. For males and females for the 

 second reading, there is no overlap of interval 



412 



