シャム湾におけるカジキ延縄試験操業結果

In four-days experimental long line operations near Samui island in the Gulf of Thailand in November 1982, black marlin was caught at a rate of 1.03 fish per 100 hooks. While the catch fluctuated by operations from 0.16 to 2.15 fish per 100 hooks, the differences in hooking rate between either hooks put on two kinds of baits (local pelagic fishes vs saury from Japan) or hooks suspended at different depths (20～40 m vs 40～70 m) were not significant. The fish caught were all small-sized, from 129 cm FL and 14.0 kg BW to 198 cm FL and 62.5 kg BW. Body weight (kg) related to fork length (cm) as BW=6.808 FL²·⁹⁸ 10-⁶ with both sexes combined. The sex ratio was much biassed in favor of male (4.75). Although gonads of almost all the males and females were smaller than 495 g, one female of 198 cm FL had a large ovary of 4,680 g. Half of the fish caught had in their stomach some food consisting mainly of pelagic fishes.1982年11月にシャム湾のサムイ島東方水域において,4日間にわたりカジキ延縄の試験操業をおこない,26尾のシロカワカジキを捕獲した。鈎百本当りの釣獲率は日により0.16～2.15尾の間で変動し,4日間を通じて平均1.03尾であった。餌の種類(現地購入のイワシ類とアジ類,および日本から運んだ冷凍サンマ),または鈎の垂下層(20～40m層と40～70m層)による釣獲率には有意な差はみられなかった。漁獲魚はすべて小型魚で,尾又長129cm,体重14.0kgから尾又長198cm,体重62.5kgの範囲であった。最大の個体は雌で,重量4,680gの卵巣をもっていた