| Title |
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en
The influence of warp length on trawl dimension and catch of walleye pollock Theragra chalcogramma in a bottom trawl survey
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ja
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
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| Creator |
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| Accessrights |
open access |
| Rights |
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ja
© 2005 公益社団法人日本水産学会
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en
© 2005 The Japanese Society of Fisheries Science
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| Subject |
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Other
en
footgear contact
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Other
en
trawl dimension
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Other
en
trawl survey
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Other
en
walleye pollock
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Other
en
warp length
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NDC
664
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| Description |
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Abstract
en
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.
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| Publisher |
en
Blackwell Publishing
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| Date |
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| Language |
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| Resource Type |
journal article |
| Version Type |
AM |
| Identifier |
HDL
http://hdl.handle.net/2115/623
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| Relation |
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isVersionOf
DOI
https://doi.org/10.1111/j.1444-2906.2005.01023.x
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| Journal |
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en
Fisheries Science
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Volume Number71
Issue Number4
Page Start738
Page End747
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| File |
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fulltext
trawl.zip
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401.86 KB
(application/zip)
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| Oaidate |
2023-07-26 |
