Table 60. — Parameters of the von Bertalanffy growth curves for arrowtooth flounder, 1976 Bering Sea spring 



trawl survey. 





Otolith 





Number 

 of age 



Age 

 range 



FL 



range 



Standard 

 error of 





Parameters 





S,ex 



area' 



Data set 



readings 



(yr) 



(cm) 



curve fit 



i 



'' 00 



K 



/« 



Male 



B D 



Ail agcS 



126 



3-8 



21-54 



4.19 



44.21 



0.22 



-0.16 







Selected ages 





3-7 



21-54 



4.61 



46.78 



0.22 



0.22 



Female 



B D 



All ages 



257 



3-12 



21-66 



3.99 



79.27 



0.13 



-0.01 







Selected ages 





3-9 



21-61 



2.46 



142.91 



0.06 



0.25 



'See Figure 4. 



















Table 61. — Estimated biomass and population numbers of Pacific halibut by subarea and for all subareas combined, 1976 



Bering Sea spring trawl survey. 











Proportion 





Proportion 









Percentage 

 frequency of 



Mean 

 CPUE 



Estimated 

 biomass 



of total 

 estimated 



Estimated 

 population 



of total 

 estimated 



Mean 



size 





Weight 



FL 



Subarea 



occurrence 



(kg/km) 



(t) 



biomass 



(millions) 



population 



(kg) 



(cm) 



Inner shelf 



















4N 



9.1 



0.10 



187 



0.006 



0.5 



0.008 



0.403 



— 



4S 



8.9 



0.08 



371 



0.012 



0.3 



0.005 



1.342 



— 



1 



23.0 



0.28 



1,371 



0.044 



9.5 



0.159 



0.144 



24.4 



Outer shelf 



















and slope 



















3 



16.2 



0.19 



881 



0.028 



0.7 



0.012 



1.267 



47.5 



3 Slope 



54.5 



1.48 



286 



0.009 



0.1 



0.002 



2.974 



62.3 



2 



75.3 



5.79 



21,629 



0.699 



46.4 



0.779 



0.466 



33.1 



2 Slope 



97.5 



14.56 



6,221 



0.201 



2.1 



0.035 



2.910 



60.2 



All subareas 



















combined 



37.0 



1.57 



: 30,947 





59.6 





0.519 



33.0 



'See Figure 3. 

















: 95% cor 



ifidence limits: 20,755-41,138 t. 















The total apparent population biomass of Pacific halibut 

 ijithin the study area was 30,900 t (95% confidence limits 

 20,800-41,100 t). Although this value was remarkably close to the 

 1975 survey estimate of 30,600 t (Pereyra et al. see footnote 2), 

 both estimates may underestimate true abundance within the 

 study area as a result of trawl avoidance. 



The total number within the study area (available to the trawl) 

 was estimated to be 59.6 million individuals, a factor of 4.66 times 

 larger than the 1975 survey estimate of 12.8 million (Pereyra et al. 

 see footnote 2). In comparison to the distribution of population 

 biomass, 81.4% of the apparent population number was distrib- 

 uted in subareas 2 and 2 Slope (combined), 17.2% in the inner 

 shelf (subareas 1 , 4S, and 4N), and 1 .4% in subareas 3N, 3S, and 

 3 Slope (combined). 



Size composition. — Almost all Pacific halibut taken during the 

 survey were juveniles. The overall mean fork length was 33.0 cm, 

 and the observed range in size was 14-101 cm FL (based upon 

 2,163 field measurements; Fig. 75). In subarea 2, where 78% of 

 the apparent population occurred, the overall size-frequency 

 distribution was essentially unimodal and 91 .6% of all individuals 

 was within the size range 25-40 cm. Populations in deep water 

 (subareas 2 Slope and 3 Slope) were composed of larger individ- 

 uals, with a considerably broader distribution of sizes about each 

 mean fork length. 



In contrast with the relatively small overall size distribution 

 taken during the 1976 spring trawl survey, the size range of 

 Pacific halibut caught by the North American setline fishery in the 

 eastern Bering Sea during 1976 was 67-215 cm FL, and 75% of all 



individuals were > 100 cm FL (International Pacific Halibut 

 Commission 1977"). 



Longhead dab. 



Distribution and abundance. — Longhead dab was widely dis- 

 tributed throughout the southeastern Bering Sea at depths less 

 than approximately 55-65 m, with highest abundance in central 

 Bristol Bay (Fig. 76). Overall, longhead dab occurred at 118 

 (27.1%) of the 435 grid stations, at a mean abundance of 1.62 

 kg/km trawled (Table 62). 



The total apparent population biomass within the study area 

 was 32,800 t (95% confidence limits 21,800-43,700 t). This value 

 was a factor of 2.95 times larger than the 1975 survey estimate of 

 11,100 t (Pereyra et al. see footnote 2). Principal causes of the 

 higher 1976 biomass estimate were apparently higher fish den- 

 sities, perhaps due to a shift in population distribution pattern 

 from shallow-water areas (depths < 10-20 m) that were not sam- 

 pled during 1975, and an extended geographical range farther 

 west into deeper water. Nearly all of the apparent population bio- 

 mass was limited to the inner shelf, with 73.7% in subarea 1. The 

 total number within the study area (available to the trawl) was 

 estimated to be 286.2 million individuals. 



'International Pacific Halibut Commission. 1976. Items of information on 

 the halibut fishery in the Bering Sea and the northeastern Pacific Ocean. Unpubl. 

 manuscr., 39 p. International Pacific Halibut Commision, P.O. Box 5009, 

 University Station, Seattle, WA 98105. 



104 



