1970) suggested that the 1952 year class domi- 

 nated here, as well as in Queen Charlotte Sound, 

 and the results (Figure 12) tend to support this 

 conclusion. The modal size was 35 cm for the 

 1960-63 period, and this corresponds to an age of 

 about 10 yr. The 1966-67 size composition data 

 also reflect the presence of a strong 1952 year class 

 series, but is is not possible to follow the series past 

 1967. Extensive fisheries removals during 1966- 

 68 resulted in sharply attenuated right-hand 

 limbs for 1968-73 size composition curves, and the 

 1952 year class series was presumably swallowed 

 up in these removals. 



As in Queen Charlotte Sound, the strong 1961- 

 62 year class series first showed up on the 1970 

 landings, when there was a mode at 35 cm. Be- 

 cause the biomass of older fish had been drastic- 

 ally reduced by the extensive fisheries removals of 

 1966-68, these year classes dominated the catches 

 in the first year they appeared and in each sub- 

 sequent year. 



Age Composition 



Queen Charlotte Sound 



Age composition data for the Washington trawl 

 landings from Queen Charlotte Sound have been 

 collected since 1966. A series of data taken over 

 the entire year is available for each year during 

 1967-73. 



The procedure used to estimate the age composi- 

 tion of the 1967-73 landings was identical to that 

 employed in the section on size composition. The 

 number of fish landed in each time stratum was 

 combined with the age-frequency data for that 

 stratum to estimate the number of fish landed by 

 age-group, sex, and time stratum. Pooling these 

 data by year and dividing by the total Washington 

 trawl effort expended in Queen Charlotte Sound 

 yielded annual estimates of the number caught 

 per hour, by age-group, and of percent age compo- 

 sition (Figure 13). 



The 1952 year class series was centered around 

 age 13 in 1965 and was almost fully vulnerable to 

 fishing when the Queen Charlotte Sound fishery 

 began its dramatic expansion. The cumulative ef- 

 fects of the extensive removals of 1966-67 were 

 such that the 1951-53 year classes no longer domi- 

 nated the catches after 1967-68. The 1952 year 

 class series was exploited far more intensively 

 than preceding year classes, and by the time the 

 1951-53 year classes were 17-19 yr old, they were 



FISHERY BULLETIN: VOL. 75, NO. 2 



QUEEN CHARLOTTE SOUND WASHINGTON - VANCOUVER IS. 



30- 

 20- 



10- 



1968 



20 



20 



10- 





 20 

 10 





 20- 

 10- 



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20 

 10 

 



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10 15 20 



Age (years) 



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5 10 15 20 25 



Age tyeors) 



FIGURE 13. — Changes in the age composition (sexes combined) 

 of Pacific ocean perch in commercial catches, 1967-73. The 

 number of fish caught per hour is shown for each year, and the 

 1952 and 1961 year classes have been indicated by shading. 



less abundant than the relatively weak 1948-50 

 year classes had been at corresponding ages. This 

 can be seen by comparing the abundance of 17-19 

 yr olds in 1970 (45 fish caught per hour) with their 

 abundance in 1967 (118 fish caught per hour). 



During 1970 and 1971, recruitment of the 

 strong 1961 and 1962 year classes to the fishery 

 restored the abundance of Pacific ocean perch to 

 1967 levels (Figure 13) and the number of fish 

 caught per hour continued to increase through 

 1973. The condition of the QCS stock in 1973 was 

 far from satisfactory, however, since it was made 

 up of much younger fish than those characterizing 

 even the 1967 stock. 



Washington-Vancouver Island 



No age composition data were available for 

 Pacific ocean perch catches from the WVI stock 

 until 1966, and it was not until 1967 that an 

 adequate series of age composition samples was 

 collected (Table 5). Age composition data on the 

 WVI catches were quite limited, so no attempt was 

 made to treat different time strata separately. 



Age composition data for 1967-73 are remark- 

 ably similar to corresponding data from Queen 

 Charlotte Sound (Figure 13). The harvests of 

 1966-68 sharply reduced the biomass of the 1952 



380 



