GUNDERSON: POPULATION BIOLOGY OK SKHASTKS AU'TUS 



TABLE 13. — Proportion mature in each length and age-group, for female Pacific ocean perch from the WVI 

 stock. Cells with only one observation were not considered. 



Length (cm) 



10 



11 



12 



13 



14 



15 



16 



Proportion 



mature by 



length 



Number 

 examined 



28 



29 



30 



31 



32 



33 



34 



35 



36 



37 



38 



39 



40 



41 



42 



43 



44 



45 



46 



47 



48 



49 

 Proportion 

 mature by 

 age 

 Number 

 examined 



0.00 



0.00 



1.00 



000 



067 



1.00 



000 



0.40 

 0.33 

 0.67 

 1.00 

 0.75 



000 

 0.00 

 038 



059 

 0.77 

 75 



0.89 

 1.00 



0.00 

 025 



0.70 

 0.50 

 0.70 



1.00 

 1.00 



1.00 



0.57 

 0.67 



0.92 

 0.95 

 0.86 

 0.88 

 1.00 

 1.00 



1.00 

 1.00 

 0.88 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 



1 50 1 

 1.00 

 0.85 

 0.83 

 1.00 

 0.93 

 1.00 

 1.00 

 1.00 

 100 

 1.00 



0.33 0.25 0.42 0.46 0.60 0.65 0.87 0.98 0.94 

 3 8 12 24 67 81 101 105 103 



1.00 

 1.00 

 0.80 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 



0.80 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 



98 1.00 

 98 219 



0.00 

 0.00 

 0.00 

 0.00 

 0.00 

 0.33 

 0.44 

 0.65 

 0.79 

 0.87 

 0.97 

 0.97 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 



3 



2 



3 



5 



7 



15 



32 



46 



100 



105 



123 



111 



65 



69 



34 



46 



26 



13 



11 



2 



2 



1 



FIGURE 19.— Length-maturity relation for QCS and WVI stocks 

 of Pacific ocean perch, by sex. 



ocean perch in the QCS and WVI stocks (Table 14). 

 Predicted curves for proportion mature at each 

 length have been calculated and are represented 

 by the solid lines (QCS stock) and dashed lines 

 (WVI stock) in Figure 19. These curves, and the 

 Z .5o estimates they are based on, indicate that both 



TABLE 14. — Estimated values of parameters for the equations 

 used to examine length and age at maturity for Pacific ocean 

 perch. 



Males 



Females 



1 For test of between-stock differences in /q 50 

 2 For test of between-stock differences in tq 50 



males and females mature at a much smaller size 

 off Washington and Southwest Vancouver Island 

 than they do in Queen Charlotte Sound. 



In order to examine the significance of 

 between-area differences further, the variance of 

 / 5 was approximated by using the delta method: 



Var(/ 050 ) -Var "/)=^<Var 



a) 



+ f^Var (/3) - 2 -^ Cov (a, /3). 



This variance was estimated for each sex and 

 area considered ( Table 14) using information from 



389 



