Table 39. — Proportions of females in the estimated population of flathead sole by age group and geographical 

 area, 1976 Bering Sea spring trawl survey. 1 



Age group (yr) 



Subarea 2 



<2 



All ages 



10 11 >12 combined 



Inner shelf 



1 

 Outer shelf 

 and slope 



3S 



3 slope 



2 



2 slope 



0.50 



Proportion of females 



1.00 0.40 0.18 0.23 0.50 0.25 0.87 0.45 



— 0.41 0.51 0.42 0.51 0.53 0.44 0.52 0.43 0.32 0.45 0.49 



— — — 0.76 0.83 0.70 0.53 0.47 0.54 0.30 0.56 0.60 



— 0.36 0.47 0.43 0.53 0.40 0.33 0.33 0.45 0.25 0.44 0.38 



— 0.24 0.00 0.52 0.81 0.72 0.74 0.69 0.83 0.70 0.85 0.75 



All subareas 

 combined 



— 0.37 0.48 0.43 0.52 0.43 0.36 0.35 0.47 0.26 0.48 



0.41 



'Based upon sampled individuals for which sexes could be determined. Populations in subareas 3N, 4S, and 

 4N are not included because no length-frequency data were collected. 

 2 See Figure 3. 



Table 40. — Length-weight relationships observed for flathead sole during the 1976 Bering Sea spring trawl survey, 

 with testing for between-area and between-sex differences. 





Otolith 

 area' 



Number 

 sampled 



TL 



range 



(cm) 



Length-weight coefficients 

 a b 



Predicted weight-; 



it-length 



Sex 



10 cm 





20 cm 



30 cm 

























Males 



B 



112 



14-35 





0.0038 



3.2946 



7.4 





72.6 



276.4 





D 



70 



13-34 





0.0085 



3.0319 



9.1 





74.7 



255.4 





Both areas 























combined 



182 



13-35 





0.0043 



3.2544 



7.6 





72.8 



272.7 



Females 



B 



65 



10-39 





0.0054 



3.1593 



7.8 





69.7 



251.1 





D 



69 



10-38 





0.0101 



2.9680 



9.3 





73.1 



243.6 





Both areas 























combined 



134 



10-39 





0.0073 



3.0696 



8.5 





71.6 



248.9 



Overall 





316 



10-39 





0.0053 



3.1784 



8.0 





72.6 



263.6 



Analysis 



of covariance 

































Tests for differences 2 











Slope (6) 





Common 



means 





df 





F ratio 



df 





F ratio 



Males between areas B and D 







1:178 





7.15** 





— 





— 



Females between areas B and D 





1:130 





6.70* 





— 





— 



Between 



sexes in area B 







1:173 





3.49 





1:174 



36.6** 



Between 



sexes in area D 







1:135 





0.39 





1:136 



3.39 



'See Figure 4. 





















2* _ 



-P ==0.05, ** = P >0.01. 



















Age-length relationship and growth. — Because only a limited 

 number of otoliths were collected in otolith areas B (262) and D 

 (130), data from the two areas were combined to create more 

 complete age-frequency tables. Results of the growth curve fit- 

 tings are summarized in Table 41 and Figure 52. Male flathead 

 sole showed a faster growth completion rate (see Equation (24)) 

 than females, although the male asymptotic total length (selected 

 ages) was only 10.1% that of females. 



Pacific cod. 



Distribution and abundance. — Pacific cod were widely dis- 

 tributed over the study area, being taken at 275 (63. 2%) of the 435 

 grid stations, at an overall mean abundance of 5.12 kg/km trawled 

 (Table 42). High densities, on a weight basis (i.e., CPUE), were 

 observed only along the outer continental shelf and slope (in 

 subareas 2 Slope, 2, and 3 Slope) at bottom depths > 100-150 m 

 (Fig. 53). In shallower areas (subareas 1 and 4S), juvenile cod (age 

 1 yr) were abundant, but their weight density and total estimated 

 biomass were low. 



The total apparent population biomass of Pacific cod within 

 the survey area was 102,300 t (95% confidence limits 

 70,600-134,000 t). Although this value is a factor of 1.59 times 

 larger than the 1975 survey estimate of 64,500 1 (Pereyra et al. see 

 footnote 2), both estimates may considerably underestimate true 

 Pacific cod abundance within the study area. A primary cause of 

 underestimation may have been low catchability. Since Pacific 

 cod exhibit semidemersal behavior, only a portion of the popula- 

 tion may have been vertically distributed so as to be available to 

 bottom trawling (i.e., within 1 .9-2.7 m of the bottom). During the 

 period 1973-75, foreign fishing activities removed approximately 

 60,000 t of Pacific cod from eastern Bering Sea and Aleutian 

 Island waters per year, although not all of these catches were 

 taken within the 1975 and 1976 study area boundaries. 



The distribution of apparent population biomass observed dur- 

 ing the 1976 spring survey was 74.3% in subareas 2 and 2 Slope 

 (combined), 24.2% in subareas 3N, 3S, and 3 Slope (combined), 

 and only 1.5% in inner shelf subareas 1, 4S, and 4N (combined). 



The total number of Pacific cod within the study area (available 

 to the trawl) was estimated to be 128.2 million individuals. In 



71 



