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Results of 2012 Pollock Acoustic-Trawl Survey Bering Sea- DY1207
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Eastern Bering Sea shelf walleye pollock (Theragra chalcogramma) midwater abundance
and distribution were assessed from Bristol Bay in the United States, to Cape Navarin,
Russia, between 7 June and 10 August 2012 using acoustic-trawl techniques aboard the
NOAA ship Oscar Dyson. Most of the pollock biomass in the U.S. exclusive economic
zone (EEZ) was distributed between the Pribilof Islands and Cape Navarin, between
roughly the 80 m and 200 m isobaths. Estimated pollock abundance in midwater (between
16 m from the surface and 3 m off bottom) in the U.S. EEZ portion of the Bering Sea
shelf was 1.843 million metric tons (t), lower than in 2010 (2.323 million t) but
higher than in 2009 or 2008 (0.924 million t, and 0.997 million t, respectively).
Pollock biomass east of 170° W was 0.279 million t, the predominant length mode was
47-48 cm, and most ages ranged between 4 and 7 years. In the U.S. waters west of 170°
W, pollock biomass was 1.563 million t (65.4% of total shelf-wide biomass), and dominant
modal lengths were 23, 38, and 30 cm, corresponding to pollock aged 2, 4, and 3 years,
respectively. In Russia (0.550 million t, 23% of total biomass), modal lengths and
ages were similar, though generally smaller and younger than those in the U.S. waters
west of 170° W. Vertical distribution analyses indicated that whereas 80-90% of the
adults were within 50 m of the bottom only about 60% of the juveniles were observed
in that depth layer. Results of a paired (midwater-bottom) trawl efficiency comparison
project are presented. The preliminary spatial distribution of the euphausiid abundance
index is presented, but analyses are still in progress.
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