Table 64. 



-Comparisons of mean catch per unit fishing effort within geographical subdivisions of 

 the 1975 and 1976 study areas in the eastern Bering Sea. 





Year 



Subareas' sampled in 

 only 1 year 



Subareas' 



sampled both years 





Species 



3 Slope 2 Slope 



3N 



3S 



2 



4N 



4S 



1 



Overall 













- kg/k 



m trawled - 









Walleye 



1975 



— 



— 



198.8 



57.7 



226.8 



0.6 



39.5 



10.7 



80.5 



pollock 



1976 



15.4 



90.5 



— 



36.5 



119.2 



0.9 



1.3 



2.8 



34.0 



Pacific 



1975 



— 



— 



3.6 



2.0 



7.1 



<0.1 



0.5 



0.9 



2.7 



cod 



1976 



16.7 



27.4 



— 



4.6 



17.2 



<0.1 



0.1 



0.2 



5.1 



Yellowfin 



1975 



— 



— 



<0.1 



1.2 



15.1 



18.9 



65.0 



103.6 



34.3 



sole 



1976 



0.1 



0.0 



— 



21.7 



127.0 



23.9 



47.5 



259.0 



104.0 



Rock sole 



1975 



— 



— 



<0.1 



3.6 



10.4 



1.3 



6.4 



12.9 



5.7 





1976 



0.3 



1.5 



— 



2.7 



29.7 



0.4 



18.0 



6.9 



11.8 



Flathead 



1975 



— 



— 



3.8 



3.4 



14.9 



<0.1 



1.0 



1.6 



3.9 



sole 



1976 



2.4 



7.1 



— 



2.2 



22.3 



0.1 



0.1 



0.4 



5.0 



Alaska 



1975 



— 



— 



<0.1 



0.1 



1.2 



7.2 



12.5 



3.7 



4.1 



plaice 



1976 



0.0 



0.0 



— 



1.9 



10.0 



10.4 



29.1 



10.7 



12.2 



Greenland 



1975 



— 



— 



16.8 



5.6 



2.3 



0.9 



1.3 



0.8 



4.4 



turbot 



1976 



4.8 



19.8 



— 



4.8 



4.1 



0.2 



0.2 



0.4 



2.6 



Arrowtooth 



1975 



— 



— 



0.1 



1.1 



4.9 



0.0 



<0.1 



0.1 



1.0 



flounder 



1976 



7.0 



39.0 



— 



0.6 



5.3 



0.0 



0.0 



0.0 



2.1 



Pacific 



1975 



— 



— 



0.1 



0.1 



2.6 



0.9 



0.6 



2.0 



1.0 



halibut 



1976 



1 5 



14.6 



- 



0.2 



5.8 



0.1 



0.1 



0.3 



1.6 



'See Figures 2 and 3. 



Table 65. — Comparisons between estimates of population biomass obtained from the 1975 and 1976 

 surveys, and 1975 all-nation eastern Bering Sea commercial catches. 





Survey biomass estimates 



and 95% confidence limits 







(in parentheses) 



1975 all-nation 1 



Species 



1975 



1976 



commercial catch 











Walleye pollock 



2,426,400 



679,492 



1,285,000 





(2,001,600-2,851,100) 



(480,060-878,925) 





Pacific cod 



64,500 



102,282 



57,300 





(51,500-77,500) 



(70,581-133,983) 





Yellowfin sole 



1,038,600 



2,094,589 



65,800 





(870,800-1,206,400) 



(1,170,499-3,018,678) 





Rock sole 



170,300 



236,067 



11,100 





(138,300-202,200) 



(79,984-392,151) 





Flathead sole 



113,000 



99,430 



5,500 





(93,900-132,100) 



(63,848-135,012) 





Alaska plaice 



127,100 



243,662 



2,600 





(101,800-152,800) 



(190,174-297,150) 





Greenland turbot 



126,700 



51,013 



64,800 





(112,700-140,700) 



(43,247-58,778) 





Arrowtooth flounder 



28.000 



40,822 



20,800 





(22,700-33,300) 



(29,990-51,654) 





Pacific halibut 



30.600 



30,947 



300 





(18,700-42,600) 



(20,755-41,138) 





'Data on file at Northwest and Alaska Fisheries Center, 2725 Montlake Blvd. E, Seattle, WA 

 98112. 



Walleye pollock. — Although walleye pollock was widely 

 distributed over the eastern Bering Sea continental shelf during 

 both the 1975 and 1976 surveys (Fig. 82), the geographical density 

 distribution observed during April-June 1976 appeared to be 

 shifted (relative to August-October 1975) west and off the shelf. 

 While this may have been caused by lower sampling efficiency 

 during spring and early summer when more individuals were 

 distributed in midwater for spawning or feeding, there is also in- 

 creasing evidence that substantial densities of adult walleye 

 pollock (44-50 cm FL) extend out from the shelf over deep water 

 (Okada 1977, ,0 1978"). 



Because the few echosounding records taken during the 1976 

 survey do not support the hypothesis that large abundances of 



walleye pollock were in midwater during daylight hours within the 

 shelf survey area, and if the density fields observed during 1975 

 and 1976 (Fig. 82) are taken as indicating seasonal distributions, 

 interpretations would then be: 1) During summer, walleye pollock 

 invade the continental shelf, with high densities of adults (2-6 yr) 



'"Okada, K. 1977. Preliminary report of acoustic survey on pollock slocks in 

 the Aleutian Basin and adjacent waters in summer of 1977. Unpubl. manuscr., 3 

 p. Fishery' Agency of Japan, 2-1 Kasumigaseki, Chiyoda-ku, Tokyo, Japan. 



"Okada, K. 1978. Preliminary report of an acoustic and midwater trawl 

 survey on pollock stocks in the Aleutian Basin and adjacent waters in the summer 

 of 1978. Unpubl. manuscr., 6 p. Fishery Agency of Japan, 2-1 Kasumigaseki, 

 Chiyoda-ku, Tokyo, Japan. 



114 



