Table 28. — Estimated population size of yellowfin sole age groups and year classes within survey subareas of the 

 eastern Bering Sea, 1976 spring trawl survey.' 





<3 



4 



5 



6 



7 



8 



9 



10 



Subarea ! 



— 



1972 



1971 



1970 



1969 



1968 



1967 



1966 





















Inner shelf 



















4N 



11.0 



58.4 



103.5 



128.3 



77.3 



38.2 



35.9 



17.5 



4S 



36.9 



89.1 



204.6 



377.9 



381.4 



219.2 



203.2 



96.2 



1 



(69.2) 



(119.0) 



(546.5) 



(1,607.2) 



(2,139.2) 



(1,658.4) 



(1,637.2) 



(765.8) 



Outer shelf 



















3 



— 



0.4 



11.4 



72.2 



131.7 



130.6 



138.8 



71.5 



2 



(0.1) 



(13.0) 



(147.5) 



(564.8) 



(819.0) 



(616.2) 



(593.9) 



(284.4) 



All subareas 



combined (117.2) (279.9) (1,013.5) (2,750.4) (3,548.6) (2,662.6) (2,609.0) (1,235.4) 



Proportion 



of total 0.008 0.018 0.066 0.178 0.230 0.173 0.169 0.080 



Subarea 



11 

 1965 



12 

 1964 



13 

 1963 



14 

 1962 



15 

 1961 



16 

 1960 



2 17 Age All ages 



— unknown combined 



Inner shelf 



4N 



4S 



1 

 Outer shelf 



millions of Fish 



5.4 



32.8 



(239.7) 



5.8 



33.2 



(205.4) 



3.6 



21.6 



(121.5) 



1.8 



13.0 

 (68.5) 



2.0 

 11.2 

 (57.8) 



0.1 

 1.4 

 (5.8) 



0.2 

 1.3 

 (2.7) 



0.9 

 6.6 

 (4.5) 



489.9 

 1,729.6 

 (9,248.4) 



3 



23.1 



21.1 



13.1 



7.2 



6.1 



0.7 



0.4 



0.9 



629.2 



2 



(92.9) 



(82.6) 



(49.5) 



(27.3) 



(23.3) 



(3.1) 



(1.2) 



(2.3) 



(3,321.1) 



All subareas 





















combined 



(393.9) 



(348.1) 



(209.3) 



(117.8) 



(100.4) 



(11.1) 



(5.8) 



(15.2) 



(15,418.2) 



Proportion 





















of total 



0.026 



0.023 



0.014 



0.008 



0.007 



0.001 



< 0.001 



0.001 





'Parentheses indicate estimates that may be badly biased due to sampling problems. 

 2 See Figure 3. 



only be evaluated by comparisons with independent estimates of 

 age composition from other stock assessment programs. 



The numbers of individuals within each age group of the sam- 

 pled population (available to capture by trawling) are summarized 

 in Table 28. The estimates from geographical subareas 1 and 2, 

 and also all subareas combined, are considered to be biased due to 

 sampling errors caused by the effects of migration. But if biases 

 were not age specific, the proportion of each age group within the 

 available population may still be estimated with relative accuracy. 

 The relative age-frequency distributions observed in different geo- 

 graphical regions of the study area are compared in Figure 39. 



In general, major features of the age composition observed in 

 all geographical subareas were quite similar, although some dif- 

 ferences were evident. Overall, 75.0% of the apparent population 

 was distributed within age groups 6, 7, 8, and 9 yr. In subareas 4N 

 and 4S, the proportions of the apparent populations that were 5 

 yr or younger were approximately a factor of 4-7 times higher 

 than observed in the other geographical regions. In subareas 3N 

 and 3S, the apparent population was composed of relatively 

 higher proportions of age groups 8 and older than in all other 

 areas. 



Sex ratio. — Proportions of females in the apparent yellowfin 

 sole population are summarized in Table 29. The overall propor- 

 tion of females was 0.52, and females predominated in all geo- 

 graphical regions except subarea 1. There were no evident age- 

 related trends in sex ratio. 



Length-weight relationship. — A total of 506 individuals from 

 the yellowfin sole populations in otolith areas A and C (Fig. 4) 

 were measured for total length and weight (Table 30, Fig. 40). The 

 length-weight relationships of male and female populations in 



otolith area A significantly differed, with females approximately 

 1-9% heavier at each length than males. 



Geographical differences were also observed between popula- 

 tions in otolith areas A and C. Up to approximately 20 cm TL, 

 both males and females showed significantly higher weights-at- 

 length (up to 48% heavier at 10 cm length) in otolith area A. At 

 sizes > 20 cm, males and females had higher weights-at-length in 

 otolith area C. 



Age-length relationship and growth. — A total of 1,007 

 yellowfin sole otoliths were collected in otolith area A and 100 in 

 otolith area C. Results of the growth curve fittings are sum- 

 marized in Table 31. Male and female populations had very 

 similar growth characteristics, although females showed a slightly 

 higher growth completion rate and approximately 1% larger 

 asymptotic total length (Fig. 41). 



Rock sole. 



Distribution and abundance. — Rock sole were widely 

 distributed along the outer continental shelf and the Alaska 

 Peninsula into Bristol Bay (Fig. 42). Overall, rock sole were taken 

 at 235 (54.0%) of the 435 grid stations, at a mean abundance of 

 11.81 kg/km trawled (Table 32). Centers of high density were lo- 

 cated in subarea 2 (north of Unimak Island and southeast of St. 

 George Island), subarea 4S (directly east of the Pribilof Islands), 

 and subarea 1 (directly off Port Moller). In general, catch rates 

 were low throughout other regions of the observed range. 



The total apparent population biomass was 236,000 t (95% 

 confidence limits 80,000-392,000 t), approximately 39% larger 

 than the estimate of 170,000 1 from the 1975 survey (Pereyra et al. 

 see footnote 2). While it is difficult to assess the true accuracy of 



55 



