Table 34. — Proportions of females in the estimated population of rock sole by age group and geographical area, 1976 



Bering Sea spring trawl survey.' 



All 

 ages 

 com- 

 bined 



Age group (yr) 



Subarea : 



<3 



10 



11 



12 



15 ==16 



Proportion of females 



Inner shelf 



4S — — 0.41 0.50 0.51 0.44 0.43 0.61 0.93 0.99 



1 0.75 1.00 0.65 0.55 0.50 0.38 0.34 0.57 0.96 0.98 



Outer shelf 

 and slope 



1.00 0.77 

 — 0.93 



1.00 

 1.00 



1.00 

 LOO 



3S 



— — 0.21 0.53 0.53 0.11 0.82 0.97 1.00 1.00 — — — — 

 0.49 1.00 0.62 0.48 0.55 0.41 0.34 0.51 0.91 0.94 1.00 0.58 1.00 1.00 



Based upon sampled individuals for which sexes could be determined. 

 ; See Figure 3. 



Table 35 



. — Length-weight relationships observed for rock sole during the 1976 Bering ! 



vj spring 





trawl survey 



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







Otolith 



Number 



TL 

 range 



Length-weight coefficients 



Predicted weight 



-at-length 



Sex 



area' 



sampled 



(cm) 



a 



6 



10 cm 20 cm 



30 cm 





















grams 





Males 



A 



80 



12-32 



0.0O40 



3.1908 



6.1 56.5 



206.3 





B 



129 



23-39 



0.0082 



3.1038 



10.4 89.7 



315.8 





D 



80 



21-33 



0.0032 



3.3302 



6.7 68.1 



262.9 





All areas 

















combined 



289 



12-39 



0.0013 



3.6144 



5.3 65.2 



282.3 



Females 



A 



136 



13-45 



0.0063 



3.1217 



8.3 72.2 



256.1 





B 



187 



24-43 



0.0057 



3.2170 



9.3 86.7 



319.5 





D 



95 



19-38 



0.0122 



2.9693 



11.3 89.0 



296.8 





All areas 

















combined 



418 



13-45 



0.0049 



3.2333 



8.4 79.2 



294.1 



Overall 





707 



12-45 



..i 1X126 



3.4113 



6.7 71.9 



286.9 



Analysis 



of covariance 

























Tests for differences 1 







Slope (b) 





Common 



means 





df 



F ratio 



df 



F ratio 



Males between areas A, 



B, and D 





2:283 



0.22 



2:285 



80.9" 



Females between areas A, B, and D 



2:412 



1.67 



2:414 



74.6** 



Between 



sexes in area A 







1:212 



0.20 



1:213 



36.6** 



Between 



sexes in area B 







1:312 



0.71 



1:313 



0.07 



Between 



sexes in area D 







1:171 



2.70 



1:172 





'See Figure 4. 















:»* 



= P £0.01. 















0.63 

 0.53 



0.53 

 0.51 



2 Slope — 



— 



1.00 



0.86 



0.90 



0.87 



0.85 



0.93 



0.98 



0.99 



1.00 



0.88 



— 



— 



0.92 



All subareas 

 combined 0.63 



1.00 



0.63 



0.50 



0.56 



0.30 



0.43 



0.61 



0.93 



0.98 



1.00 



0.75 



1.00 



1 IX) 



0.55 



geographical regions both male and female populations showed 

 larger mean total lengths in this area. 



Flathead sole. 



Distribution and abundance. — Flathead sole were widely dis- 

 tributed along the outer continental shelf at bottom depths 

 > 75-90 m, with only scattered low-density occurrences in 

 shallower inner-shelf areas (Fig. 48). Overall, flathead sole were 

 taken at 220 (50.6%) of the 435 grid sampling stations, at a mean 

 abundance of 4.95 kg/km trawled (Table 37). A single large con- 

 centration centered in subarea 2, between St. George and Unimak 

 Islands, accounted for most of the estimated population biomass. 

 Although commonly taken in other areas of the outer continental 

 shelf and slope (subareas 3N, 3S, 2 Slope, and 3 Slope), densities 

 in those areas were relatively low. 



The total apparent population biomass of flathead sole within 

 the study area was 99,400 1 (95% confidence limits 63,800-135,000 

 t, approximately 88% of the 1975 survey estimate of 113,000 t 

 (Pereyra et al. see footnote 2). The distribution of biomass 

 among geographical regions was subarea 2, 83.9%; subareas 3N 

 and 3S, 10.3%; subareas 2 Slope and 3 Slope (combined), 3.5%; 

 and all inner shelf subareas (combined), 2.3%. 



The total number within the 1976 study area (available to the 

 trawl) was estimated to be 440.1 million individuals. The distribu- 

 tion of population numbers among geographical areas was essen- 

 tially the same as apparent population biomass. 



Size composition. — Flathead sole taken during the 1976 spring 

 survey ranged from 8 to 50 cm TL, with an overall mean total 

 length of 27.5 cm (based upon 6,479 field measurements; Fig. 49). 

 In all subareas, male populations were composed of smaller sized 



62 



