Table 50. — Length-weight relationships observed for Alaska plaice during the 1976 Bering Sea spring trawl 

 survey, with testing for between-sex differences. 









TL 















Otolith 



Number 



range 



Length-weight coefficients 



Predicted 



weight-at 



-length 



Sex 



area 1 



sampled 



(cm) 



a 



b 



10 cm 



20 cm 



35 cm 

















grams - 











Males 



A 



75 



22-37 



0.0126 



2.9676 



11.7 



91.8 



483.3 



Females 



\ 



73 



25-50 



0.0058 



3.2074 



9.3 



86.1 



518.5 



Overall 





148 



22-50 



0.0073 



3.1342 



9.9 



87.7 



506.7 



Analysis of covariance 



Between sexes in area A 



Tests for differences' 



Slope (b) 



Common means 



F ratio 



F ratio 



1:146 



'See Figure 4. 

 ! * = P <0.05. 



Greenland turbot. 



Distribution and abundance. — During the 1976 spring survey, 

 Greenland turbol were broadly distributed along the outer conti- 

 nental shelf and slope (Fig. 64), and overall, occurred at 255 

 (58.6%) of the 435 grid stations, at a mean abundance (mean 

 CPUE) of 2.56 kg/km trawled (Table 51). Highest abundance was 

 observed in deep water (subarea 2 Slope) between St. George and 

 Unimak Islands. Only low densities (mean CPUE's <0.40 kg/ 

 km) were found in inner shelf areas 1, 4S, and 4N. 



The total apparent population biomass (Estimated Biomass, 

 Table 51) within the survey area was 51,000 t (95% confidence 

 limits 43,200-58,800 t). This value was only 40.3% of the 1975 

 survey estimate of 126,700 t (Pereyra et al. see footnote 2). Prin- 

 cipal causes of the low 1976 biomass estimate may have included: 

 Seasonally related emigration to deep water outside of the study 

 area boundaries (Shuntov 1970): and the reduced northern survey 

 coverage, particularly in subarea 3N. 



During spring 1976, approximately 30.0% and 38.9% of the 

 total apparent biomass was observed in subareas 2 and 3S. Deep- 

 water populations of large individuals in subarea 2 Slope ac- 

 counted for 16.6% of the total biomass. Only 6.3% of the overall 

 apparent biomass was represented by populations in inner shelf 

 areas 1, 4S, and 4N. 



The total number of Greenland turbot within the study area 

 (available to trawling) was estimated to be 350.9 million in- 

 dividuals. As opposed to the distribution of biomass, 30.2% of 

 the total number was located in subareas 1, 4S, and 4N (com- 

 bined), and only 19.4% in subareas 2 and 2 Slope (combined). 



Size composition. — The size range of Greenland turbot was 

 9-99 cm FL, with an overall mean fork length of 21.6 cm (based 

 on 7,097 field measurements; Fig. 65). In general, three distinct 

 types of size-frequency distributions were observed. In subareas 

 4S and 4N size distributions were essentially unimodal and the 

 populations were almost exclusively composed of small, 1-yr-old 

 individuals. Populations in subareas 1, 2, 3N, 3S, and 3 Slope 

 showed size distributions with one, two, or three prominent 

 modes — at approximately 12, 22, and 34 cm FL — resulting from 

 varying proportional representation of age groups 1 , 2, and 3 yr. 

 The deepwater population in subarea 2 Slope showed the largest 

 size range (24-99 cm) and included relatively high proportions of 

 large (>60 cm), old individuals. 



Age composition. — Estimates of age-frequency distribution 

 were determined from an overall collection of 193 male and 182 

 female saccular otoliths. The observed ranges in age were males, 

 2-11 yr, and females, 2-16 yr. 



Table 51.— Estimated biomass and population numbers of Greenland turbol by subarea and for all subareas combined, 1976 



Bering Sea spring trawl survey. 



Subarea 



Proponion Proportion 



Percentage Mean Estimated of total Estimated of total 



frequency of CPUE biomass estimated population estimated 



occurrence (kg/km) (t) biomass (millions) population 



Mean size 



Weight 

 (kg) 



FL 

 (cm) 



Inner shelf 





4N 



45.5 



4S 



26.8 



1 



18.0 



Outer shelf 





and slope 





3 



86.3 



3 Slope 



90.0 



2 



"4.; 



2 Slope 



87.5 



0.25 



460 



0.009 



36.6 



0.104 



0.013 



11.7 



0.21 



895 



0.018 



61.7 



0.176 



0.014 



11.6 



0.37 



1,811 



0.036 



7.8 



0.022 



0.234 



29.1 



4.82 



23,178 



0.454 



174.9 



0.498 



0.132 



23.2 



4.76 



923 



0.018 



1.9 



0.005 



0.481 



36.7 



4.10 



15,294 



0.300 



64.4 



0.184 



0.238 



28.9 



19.78 



8.451 



0.166 



3.6 



0.010 



2.356 



59.7 



All subareas 

 combined 



58. 6 



:.56 



"51.013 



350.9 



0.145 21.6 



'See Figure 3. 



: 95<Fo confidence limits: 43,247-58,778 t. 



90 



