Table 37. — Estimated biomass and population numbers of flathead sole by subarea and for all subareas combined, 1976 



Bering Sea spring trawl surrey. 











Proportion 





Proportion 









Percentage 

 frequency of 



Mean 

 CPUE 



Estimated 

 biomass 



of total 

 estimated 



Estimated 

 population 



of total 

 estimated 



Mean 



ize 





Weight 



TL 



Subarea' 



occurrence 



(kg/km) 



(t) 



biomass 



(millions) 



population 



(kg) 



(cm) 



Inner shelf 



















4N 



22.7 



0.07 



128 



0.001 



0.7 



0.002 



0.183 



— 



4S 



17.9 



0.08 



356 



0.0O4 



2.5 



0.006 



0.145 



— 



1 



25.0 



0.36 



1,769 



0.018 



4.8 



0.011 



0.369 



31.7 



Outer shelf 



















and slope 



















3 



68.4 



2.18 



10,255 



0.103 



63.6 



0.145 



0.161 



25.0 



3 Slope 



90.9 



2.43 



471 



0.005 



1.9 



0.004 



0.244 



28.6 



2 



75.3 



22.34 



83,437 



0.839 



358.2 



0.814 



0.233 



27.8 



2 Slope 



57.5 



7.06 



3,014 



0.030 



8.4 



0.019 



0.361 



32.2 



All subareas 



















combined 



50.6 



4.95 



=99,430 





440.1 





0.226 



27.5 



'See Figure 3. 

















'95% confidence limits: 63.848-135,012 t. 















individuals than female populations (overall mean total length: 

 Males, 26.9 cm; females, 28.4 cm). Female populations showed 

 higher proportions of individuals > 30-35 cm TL. 



Differences in size composition were also evident between geo- 

 graphical areas. Largest mean total lengths (sexes combined) were 

 observed in subareas 2 Slope, 1, and 3 Slope. Populations in 

 subareas 2 and 3S (sexes combined) showed both the largest size 

 ranges and smallest individuals (size ranges: Subarea 2, 8-50 cm; 

 subarea 3S, 9-48 cm). 



Age composition. — Estimates of age-frequency distribution 

 were based upon an overall collection of 183 male and 209 female 

 saccular otoliths from areas B and D. The observed ranges in age 

 were males, 3-15 yr; females, 3-19 yr. 



The age composition of each apparent population is summar- 

 ized in Table 38, excluding subareas 3N, 4S, and 4N because no 

 length-frequency data were collected. Despite these excluded 

 areas, Table 38 includes 435.8 million (99.0%) of the estimated 

 440. 1 million individuals of the overall population (Table 37). 



Relative age distributions between sexes and geographical areas 

 are compared in Figure 50. Age groups 7, 8, and 9 yr were impor- 

 tant in all subareas, accounting for 63.8 (> 7o of the total apparent 

 population. In subareas 1 and 2 Slope, relatively large propor- 

 tions of the populations were aged 9 yr or older (40.1% and 



45.9%, respectively). Relatively large proportions of young in- 

 dividuals (<6 yr) were observed in outer shelf subareas 3S 

 (30.9%) and 2 (17.2%). 



Sex ratio. — The overall proportion of females was 0.41 (Table 

 39). Although males were more abundant than females in all areas 

 of the continental shelf (subareas 1, 2, and 3S), females 

 predominated in deep water (i.e., in subareas 2 Slope and 3 

 Slope). With the exception of the 6-yr age group, males were more 

 abundant than females at all ages in combined subareas. 



Length-weight relationship. — A total of 316 individuals from 

 the populations in otolith areas B and D were measured for total 

 length and weight (Table 40, Fig. 51). The overall observed rela- 

 tionship was W = 0.0053 L 3 -" 84 . 



Male and female populations showed statistically significant 

 differences between geographical regions in the slopes of their 

 length-weight linear regression lines. At sizes less than approx- 

 imately 20 cm, individuals of both sexes were heavier at length in 

 otolith area D. At larger total lengths, individuals were heavier in 

 otolith area B. 



A statistically significant difference was also found between 

 male and female populations in otolith area B. At > 13 cm TL, 

 male flathead sole were 1-25% heavier at length than females. 



Table 38. — Estimated population size of flathead sole age groups and year classes within survey subareas of the eastern Bering Sea, 



1976 spring trawl survey. 1 





<2 



3 



4 



5 



6 



7 



S 



9 



10 



11 



2:12 



Age 



All ages 



Subarea' 



— 



1973 



1972 



1971 



1970 



1969 



1968 



1967 



1966 



1965 



— 



unknown 



combined 





























Inner shelf 





























1 



0.10 



0.21 



— 



— 



0.01 



0.71 



0.91 



0.93 



0.28 



0.35 



1.30 



— 



4.80 



Outer shelf 





























and slope 





























3S 



0.06 



0.64 



0.29 



10.48 



7.85 



26.69 



10.65 



3.20 



0.92 



0.78 



0.90 



0.06 



62.52 



3 Slope 



— 



— 



— 



0.03 



0.07 



0.71 



0.53 



0.28 



0.09 



0.08 



0.13 



— 



1.92 



2 



2.57 



4.53 



1.41 



31.74 



21.47 



112.89 



74.07 



41.55 



17.11 



21.68 



28.02 



1.18 



358.22 



2 Slope 



— 



0.05 



0.01 



0.07 



0.09 



1.39 



1.60 



1.30 



0.69 



1.16 



1.82 



0.16 



8.34 



All subareas 



combined 2.73 5.43 1.71 42.32 29.49 142.39 87.76 47.26 19.09 24.05 32.17 1.40 435.80 



Proportion 



of total 0.006 0.012 0.004 0.097 0.068 0.327 0.201 0.108 0.044 0.055 0.074 0.003 



'Populations in subareas 3N. 4S, and 4N are not included because no length-frequency data were collected. 

 : See Figure 3. 



70 



