Characterizing walleye pollock (Theragra chalcogramma) winter distribution from opportunistic acoustic data

Abstract Barbeaux, S. J., Horne, J. K., and Dorn, M. W. 2013. Characterizing walleye pollock (Theragra chalcogramma) winter distribution from opportunistic acoustic data. – ICES Journal of Marine Science, 70: 1162–1173. In 2003, acoustic data from 25 000 km of ship track lines were collected from two fishing vessels participating in the eastern Bering Sea walleye pollock (Theragra chalcogramma) fishery. Although these data were not calibrated or collected on a systematic grid, their broad temporal extent combined with high spatial resolution facilitated the examination of the distribution and behaviour of fished aggregations. To demonstrate their scientific applicability, these data were used to identify the spatio-temporal dynamics of pollock aggregations over scales ranging from hundreds of metres to hundreds of kilometres and from minutes to months. The spatial analysis identified three levels of pollock aggregation. The largest regions of high pollock density had an average diameter of 110 km and were comparable with distinct fishing grounds identified by fishers. The next smaller areas of high pollock density had a diameter between 2.5 and 6 km. Within these areas were clusters of pollock at even higher densities. The extent of the smallest aggregations ranged in diameter from 0.1 km in daylight to 0.6 km at night. Time-series analysis identified vertical and horizontal diel changes in pollock distribution and an overall decline in pollock density over the study period.

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Corrigendum: Using acoustic data from fishing vessels to estimate walleye pollock (Theragra chalcogramma) abundance in the eastern Bering Sea

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2011-101 ◽

2011 ◽

Vol 68 (8) ◽

pp. 1508-1509

Author(s):

Taina Honkalehto ◽

Patrick H. Ressler ◽

Richard H. Towler ◽

Christopher D. Wilson

Keyword(s):

Bering Sea ◽

Walleye Pollock ◽

Theragra Chalcogramma ◽

Acoustic Data ◽

Eastern Bering Sea ◽

Fishing Vessels ◽

Walleye Pollock Theragra Chalcogramma

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Using acoustic data from fishing vessels to estimate walleye pollock (Theragra chalcogramma) abundance in the eastern Bering Sea

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2011-050 ◽

2011 ◽

Vol 68 (7) ◽

pp. 1231-1242 ◽

Cited By ~ 27

Author(s):

Taina Honkalehto ◽

Patrick H. Ressler ◽

Richard H. Towler ◽

Christopher D. Wilson

Keyword(s):

Bering Sea ◽

Low Cost ◽

Walleye Pollock ◽

Theragra Chalcogramma ◽

Accurate Information ◽

Commercial Fishing ◽

Acoustic Data ◽

Eastern Bering Sea ◽

Fishing Vessels ◽

Walleye Pollock Theragra Chalcogramma

Eastern Bering Sea walleye pollock ( Theragra chalcogramma ) support one of the world’s largest fisheries. Because of walleye pollock’s high recruitment variability and relatively short life span, timely and accurate abundance indices are needed for fisheries management. Walleye pollock are surveyed biennially with an acoustic-trawl (AT) survey and annually with a bottom trawl (BT) survey. The latter tracks the demersal portion of the population using chartered fishing vessels, whereas the AT survey tracks the younger, midwater portion using research vessels and is critical for evaluating prerecruit abundances. Acoustic data collected from commercial fishing vessels conducting the BT survey were analyzed to provide information on midwater walleye pollock abundance at relatively low cost. A retrospective analysis of AT survey data identified a suitable index area to track midwater walleye pollock abundance. The BT survey acoustic data in that area tracked the AT survey abundance and captured its broad spatial patterns. This study is unique because commercial vessel acoustic data were used to estimate a new annual abundance index whose performance can be evaluated by a biennial research vessel survey. The new index will benefit managers by providing more accurate information on near-term abundance trends when dedicated research ship time is not available.

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Short-term effects of commercial fishing on the distribution and abundance of walleye pollock (Theragra chalcogramma)

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2011-166 ◽

2012 ◽

Vol 69 (2) ◽

pp. 354-368 ◽

Cited By ~ 5

Author(s):

Paul D. Walline ◽

Christopher D. Wilson ◽

Anne B. Hollowed ◽

Sarah C. Stienessen

Keyword(s):

Walleye Pollock ◽

Small Scale ◽

Theragra Chalcogramma ◽

Commercial Fishing ◽

Short Term ◽

Acoustic Data ◽

Walleye Pollock Theragra Chalcogramma ◽

Vertical Distributions ◽

Acoustic Surveys ◽

Abundance And Distribution

Replicate acoustic surveys conducted near Kodiak Island, Alaska, USA, during summers 2001, 2004, and 2006 showed that the short-term effect of commercial fishing activities on walleye pollock ( Theragra chalcogramma ) during this period was small, in most cases too small to detect. An area with commercial fishing and a nearby comparison area where commercial fishing was prohibited were surveyed before and during the fishery. Acoustic data were used to assess changes in the abundance, geographical and vertical distributions, and small-scale spatial patterns of walleye pollock, which may have occurred after the fishery commenced. A decrease in biomass after fishing began was detected only in 2004. No changes were detected in geographical or vertical distributions that could be attributed to the fishery in any year. Adults did not appear to aggregate or disperse in response to the fishery. Juvenile aggregations did differ between the prefishery and fishery surveys in 1 of the 2 years when juveniles were present. These data suggest that changes in walleye pollock abundance and distribution caused by the fishery are likely quite small compared with natural fluctuations.

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