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The influence of warp length on trawl dimension and catch of walleye pollock Theragra chalcogramma in a bottom trawl survey

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Title: The influence of warp length on trawl dimension and catch of walleye pollock Theragra chalcogramma in a bottom trawl survey
Other Titles: スケトウダラ着底トロール調査におけるワープ長の違いが網形状と漁獲に与える影響
Authors: Fujimori, Yasuzumi1 Browse this author →KAKEN DB
Chiba, Kenji Browse this author
Oshima, Tatsuki Browse this author
Miyashita, Kazushi Browse this author →KAKEN DB
Honda, Satoshi Browse this author
Authors(alt): 藤森, 康澄1
Keywords: footgear contact
trawl dimension
trawl survey
walleye pollock
warp length
Issue Date: Aug-2005
Publisher: Blackwell Publishing
Journal Title: Fisheries Science
Volume: 71
Issue: 4
Start Page: 738
End Page: 747
Publisher DOI: 10.1111/j.1444-2906.2005.01023.x
Abstract: We examined variation in trawl dimension, bottom contact, and catch with differing warp lengths during walleye pollock surveys conducted by the Fisheries Research Agency. The ratio of warp length to fishing depth (scope ratio) was set at 2.5, 3.0 and 3.5 at depths of 110 m. At a 2.5 scope ratio, the net mouth shape and footgear contact fluctuated, as the trawl door did not contact the bottom. Footgear contact was complete when the scope ratio was 3.0 or more. Walleye pollock, sculpins, and flatfishes were the main catch in all tows, and the catch increased with scope ratio. There was no difference in the length frequency of n= 300 walleye pollock captured at 2.5 and 3.0 scope ratio. However, the length frequency at 3.5 was significantly different from that of other scope ratios. These results suggest the following: at a scope ratio of 3.0 or more, the trawl door will not leave the bottom at any depths. To compliment echo surveys for walleye pollock, a 3.0 scope ratio would be optimal, since the catch data for a 3.5 scope ratio was dissimilar from that of scope ratios.
Rights: © 2005 公益社団法人日本水産学会
© 2005 The Japanese Society of Fisheries Science
Type: article (author version)
Appears in Collections:水産科学院・水産科学研究院 (Graduate School of Fisheries Sciences / Faculty of Fisheries Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 藤森 康澄

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