瀬戸内海のタコの漁況について

Note on the fishing condition of the common octopus, octopus vulgaris CUVIER, in the Inland Sea of Seto, Japan

Nishikawa Sadaichi

広島大学水畜産学部紀要

Journal of the Faculty of Fisheries and Animal Husbandry, Hiroshima University

(1) 潮岬や足摺崎の沖合を通る黒潮水温の高低および内海沿岸各地の降水量が内海のタコの漁獲量に如何に影響をおよぼすかについて検討を行なった.
(2) 瀬戸内海の各水域におけるタコの年間漁獲量の年々変動をその漁獲の前年の潮岬，足摺崎，の4， 5， 6月及び7， 8， 9月の3カ月の平均水温と比較した.便宜上，水温は36年間の平均からの偏差で表示した.
(3) 潮岬や足摺崎の4， 5， 6月及び7， 8， 9月の黒潮干均水温の高温年が翌年のタコ生産に稍々良いことが36年間の資料を検討して窺われた.特に春季水温が内奥程其特徴を表わし夏季水温は外洋に近い海域では反対の場合を生じた.
(4) 瀬戸内海各府県の前年の降水量(6-10月)と当年のタコの漁獲量を比較したところ，大体において内奥程前年の降水量と逆の関係を示すことが窺わかたが外洋に近い海区でこの関係が明かでなかった.

1. Examination has been made as to the extent to which the annual catch of octopus in the Seto Inland Sea is affected by the water temperatures of the Kuroshio region off Shiono-misaki and Ashizuri-zaki and by the precipitation in various parts of the Seto Inland Sea.

2. Year-to-year fluctuation of the octopus catch in different parts of the Seto Inland Sea during 1925-60 has been compared with the spring (April-June) and summer (July-September) water temperatures at Shiono-misaki and Ashizuri-zaki in the preceding year. For convenience' sake, water temperatures were expressed in terms of the deviation from long-term (36 years) averages.

3. Analyses of the data for the 36 years suggested a tendency that, when April-June and/or July-September temperatures of the Kuroshio region off Shiono-misaki or Ashizuri-zaki are relatively high in a certain year, octopus catch in the Seto Inland Sea is comparatively rich in the next year. This tendency was especially pronounced when the octopus catches in the innermost parts of the Seto Inland Sea were correlated to the preceding year's spring water temperature of the Kuroshio region. However, it sometimes happened that the octopusc atches in the entrance parts of the Seto Inland Sea were poor in a year immediately following a relatively high summer water temperature in the Kuroshio region.

4. When year-to-year fluctuation of octopus catch in each prefecture on the Seto Inland Sea was compared with the local precipitation during June-October of the preceding year, there showed up a general tendency that octopus catches in the innermost parts of the Seto Inland Sea are rather negatively correlated to the local preciptation of the preceding year. The octopus catches in the entrance parts of the Seto Inland Sea, however, did not show such correlation to local precipitation.

Fishing industry. Fisheries [ 660 ]

jpn

広島大学水畜産学部

[ISSN] 0440-8756

[NCID] AN00213563