ポケット網実験から推定したカタクチイワシシラスに対する船曳網の網目選択性  [in Japanese] Mesh selectivity of boat seine fisheries for anchovy larvae on pocket-nets experiment  [in Japanese]

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Author(s)

    • 斎浦 耕二 SAIURA KOJI
    • 徳島県農林水産部水産課 Fisheries Division, Agriculture, Forestry and Fisheries Department, Tokushima Prefectural Government
    • 東海 正 TOKAI TADASHI
    • 東京水産大学海洋生産学科 Department of Marine Science and Technology, Tokyo University of Fisheries

Abstract

徳島県でシラスを漁獲対象とする船曳網のコッドエンドには目合260経のモジ網が使用されている。船曳網の数カ所にポケット網を装着し,曳網実験を5回実施した。カタクチイワシはコッドエンドから最も多く逸出していた。SELECTモデルを拡張してコッドエンドとポケット網の採集結果から網目選択性曲線を推定した。50%選択は漁獲量が多くなると網目から抜けにくい傾向が認められた。通常の創業では50%選択は10mm以下であり,漁獲対象としているシラスの全長に対して260経は小さく適正な目合に改善する必要がある。

The main target of boat seine fisheries in the western sea area of the Kii Channel is anchovy larvae, Engraulis japonica. The fishing gear consists of wings, body net, and codend. The gear is made of various minnow netting, and the mesh size of the codend is 260 kei : the number of twines in webbing 50 cm wide. Five experimental hauls were carried out with small-mesh pocket-nets attached to several positions on the body net and the codend. The selectivity curve for anchovy larvae was estimated with an extended SELECT model for analyzing body size (total length) distributions of the pockets catch and sample from the codend catch. Selectivity parameters were varied in the five hauls, that is, l<SUB>5</SUB>0 (the length of 50% retention) was 8.7-12.3 mm and SR (selection range=l<SUB>7</SUB>5-l<SUB>2</SUB>5) ranged from 3.0 mm to 4.7 mm. Higher catch volumes were likely to prevent small fish from escaping. In this fishery, the codend catch weight usually exceeds 20 kg, which means that the l<SUB>5</SUB>0 is smaller than 10 mm, and few anchovy larvae smaller than 15 mm are distributed in this fishing ground. Therefore, the current codend mesh size, 269 kei is too fine, and consequently enlargement of the mesh size should be examined for fisheries management and product management.

Journal

  • NIPPON SUISAN GAKKAISHI

    NIPPON SUISAN GAKKAISHI 69(4), 611-619, 2003-07-15

    The Japanese Society of Fisheries Science

References:  27

Cited by:  8

Codes

  • NII Article ID (NAID)
    110003145559
  • NII NACSIS-CAT ID (NCID)
    AN00193422
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    00215392
  • NDL Article ID
    6652757
  • NDL Source Classification
    ZR26(科学技術--農林水産--水産)
  • NDL Call No.
    Z18-345
  • Data Source
    CJP  CJPref  NDL  NII-ELS  J-STAGE  NDL-Digital 
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