太平洋道東沖マサバ資源調査に適した調査用流し網における目合の組み合わせ  [in Japanese] Appropriate mesh size combination of research drift net series for chub mackerel resources off Hokkaido, Pacific  [in Japanese]

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Abstract

太平洋道東沖の資源調査に用いられる調査用流し網について,回復しつつあるマサバ資源のモニターに適した目合の組み合せを検討した。これまでの同調査結果を用いて目合別の選択性曲線を推定した。6・7 月と 9-11 月の調査時期間で選択性曲線に違いが認められ,胴での羅網過程を基に産卵後の肥満度の低下を要因としてその違いを考察した。また現在の目合の組み合せでは,尾叉長 300 mm 以上での採集効率の低下が著しく,大型個体の資源を過小評価する可能性がある。目合 82 mm と 106 mm の網を追加する改善策を提案した。

A drift net series consisting of several net panels of nine different mesh sizes was used to investigate pelagic fish resources in the waters off Hokkaido, Japan during June-July and September-November. This study aimed to determine the most appropriate mesh size combination of research drift net series with an approximate constant catching intensity over a large range of fish length for research on chub mackerel <i>Scomber japonicus</i> the resources of which are in the process of recovering. Selection curves were estimated for the mesh sizes from the data of the drift net research carried out in the two periods of June-July and September-November. Across all mesh sizes, fish caught in June-July had slightly greater fork length than those in September-November, and they also had a lower condition factor implying a smaller body girth following spawning. The pooled relative catching intensity steeply declined for fish with fork length over 300 mm at the current mesh combination, suggesting a possible underestimation of stocks of large fish. A simulation showed that the addition of two panels with larger mesh sizes (82 and 106 mm) kept a constant intensity for fish below 350 mm fork length.

Journal

  • NIPPON SUISAN GAKKAISHI

    NIPPON SUISAN GAKKAISHI 82(3), 290-297, 2016

    The Japanese Society of Fisheries Science

Codes

  • NII Article ID (NAID)
    130005156367
  • NII NACSIS-CAT ID (NCID)
    AN00193422
  • Text Lang
    JPN
  • Article Type
    journal article
  • ISSN
    0021-5392
  • NDL Article ID
    027445992
  • NDL Call No.
    Z18-345
  • Data Source
    NDL  IR  J-STAGE  JASI 
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