BEACHAM: VARIABILITY IN SIZE AND AGE OF ATLANTIC COD 



55 



 £ 



50 



o 



£ 



1 45 



c 



01 



c 

 o 



•o 

 <u 



40 



35 



30 



a Female 



o Male 



No Data Available 



1959 



1951 



1963 1965 1967 1969 



1971 



1973 1975 1977 1979 



Figure 5. — Median length at sexual maturity for Atlantic cod caught during summer Canadian groundfish 

 surveys in Subdivision 4Vs, 1959-79. Vertical bars indicate 95% confidence limits. 



79, median age was 2.7 yr for males and 2.9 yr for 

 females, a significant decline (P<0.01). 



Division 4W 



Atlantic cod populations in Subdivision 4Vs and 

 Division 4W are considered to be a unit stock for 

 management purposes (Gray 1979). There were 

 similar trends in L 50 between Atlantic cod in Subdivi- 

 sion 4Vs and those of Division 4 W (Fig. 8). In par- 

 ticular, there was a rapid decline in L 50 between 1969 

 and 1972, with L J0 for males declining from 48 to 37 



cm in 4 yr, and with values for females declining from 

 50 to 36 cm. Subsequently, L J0 values for both sexes 

 have generally remained below 40 cm. Atlantic cod in 

 Division 4 W were similar to those of the other areas in 

 regards to a decrease in L 50 with time. The difference 

 in lengths in which males and females attained 

 maturity was greater in the 1960'sthaninthe 1970's, 

 indicating that the rate of decline in L 50 was faster in 

 females than in males. 



A J0 values declined over time until the early 1970's 

 (Fig. 9). A low value of 2.2 yr for males and 2.3 yr for 

 females was reached in 1978, a decrease of about 



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