産卵床の増減からみたビワマス資源への遊漁の影響評価

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  • 尾田 昌紀
    三重大学大学院生物資源学研究科 鳥取県水産試験場
  • 淀 太我
    三重大学大学院生物資源学研究科

書誌事項

タイトル別名
  • Assessment of recreational fishing impact on the Biwa salmon resource based on redd abundance at ten Lake Biwa inlet streams in 2015
  • サンランショウ ノ ゾウゲン カラ ミタ ビワマス シゲン エ ノ ユウギョ ノ エイキョウ ヒョウカ

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抄録

<p>Biwa salmon, an endemic species and important fishery resource in Lake Biwa, migrate upstream from the lake in inlet streams during the spawning season. Monitoring the number of spawning redds in such inlet streams can provide an assessment of the Biwa salmon population, similar population assessments having been conducted for Bull trout (North America) and Sakhalin taimen/Masu salmon (Hokkaido, Japan). Numbers of recreational fishermen targeting Biwa salmon began to increase around 2006, becoming especially significant over the past four years. However, the potential negative impact of such on the Biwa salmon resource is a concern. To assess the current impact of fishing on Biwa salmon, spawning fish abundance and total redd counts of the latter in ten Lake Biwa inlet streams during 2015 were compared with the results of a previous study conducted in 2008, when recreational fishing was practiced on a smaller scale. Although spawning varied in each stream, the total redd count was comparable (1,066 in 2008 vs. 1,159 in 2015), indicating little impact on Biwa salmon resources due to the recent increase in recreational fishing pressure. Comparisons of the body sizes of mature fish showed no significant difference in average body size between 2009 and 2015, a further indication of relatively low fishing impact. It was concluded, therefore, that the increase in recreational fishing has had little effect on the Biwa salmon populations, likely due to the Shiga Prefecture initiatives to introduce early regulation of recreational fishing, as well as the common practice of most recreational fishermen to practice “catch and release”.</p>

収録刊行物

  • 魚類学雑誌

    魚類学雑誌 64 (1), 19-24, 2017-04-25

    一般社団法人 日本魚類学会

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