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広島大学水畜産学部紀要 7 巻 1 号
1967-07-31 発行
走島の漁業 : Ⅰ 桝網の漁獲量よりみたウマヅラハギNavodon modestus (GÜNTHER) の漁況について
Fisheries in Hashiri-shima : I. On the catch of navodon modestus (GUNTHER) by masu-ami in Hashiri-shima
村上 豊
角田 俊平
Abstract
瀬戸内海・備後灘に面する福山市の走島，宇治島および袴島の沿岸水域lこは4月から6月までの3ヶ月間約100統の小型定置網(桝網)が設置されて，多数のウマヅラハギが漁獲される.本報では. 1960年から1966 年まで7年間に走島漁業協同組合に水揚げされたウマヅラハギ漁獲量の記録を用いて解析を行ない，次の諸点を明らかにした.
1 ) 走島におけるウマヅラハギの漁期は4月， 5月および6月で. 5月上旬ならびに中旬が盛漁期である.ここでは総漁獲量の95%が桝網で， 5 %が刺網で漁獲される.
2) ウマヅラハギ漁獲量の経年変化はかなり大きく. 1960年には40 トンの漁獲量があったが. 65年には10 トンに，更に66年には3トン弱に激減している.また盛漁期においては日々の漁獲量もかなり大きく変動する.
3) 漁期を通じて漁獲量の多い網と少ない網の位置はほぼ定まっている.一般に岸の周辺却の網に多く，島の南西岸から沖合に向って設世された沖の網に少ない.これら岸の網と沖の網の漁期は等しく，両者の問に漁獲量の時期的な差異はない.
4) 岸周辺部の網による漁獲量の経日的な推移はいずれの網もほぼ等しい. しかし，漁獲量に1峰型の網と2峰型の網があることが認められた。
1 ) 走島におけるウマヅラハギの漁期は4月， 5月および6月で. 5月上旬ならびに中旬が盛漁期である.ここでは総漁獲量の95%が桝網で， 5 %が刺網で漁獲される.
2) ウマヅラハギ漁獲量の経年変化はかなり大きく. 1960年には40 トンの漁獲量があったが. 65年には10 トンに，更に66年には3トン弱に激減している.また盛漁期においては日々の漁獲量もかなり大きく変動する.
3) 漁期を通じて漁獲量の多い網と少ない網の位置はほぼ定まっている.一般に岸の周辺却の網に多く，島の南西岸から沖合に向って設世された沖の網に少ない.これら岸の網と沖の網の漁期は等しく，両者の問に漁獲量の時期的な差異はない.
4) 岸周辺部の網による漁獲量の経日的な推移はいずれの網もほぼ等しい. しかし，漁獲量に1峰型の網と2峰型の網があることが認められた。
Abstract
The file-fish, Navodon modes/us (GÜNTHER) are caught by the masu-ami, a kind of pound net, which are operated along the coast of islands in the central part of the Inland Sea of Japan. Catching data of this fish in the areas of Hashiri-shima, Uji-shima and Hakama-shima during the seven years period (1960-1966) were collected from about one hundred nets, and analysed.
1) Fishing of N. modestus are operated during the three months from April to June in this area and the most abundant catches are seen in May. About 95% of the catch is trapped by the masu-ami and about 5% is caught by the gill nets.
2) The annual catch of N. modestus shows considerably sharp fluctuation. The maximal catch during the seven years period is 40 metric tons in 1962, and the minimum is 3 metric tons in 1966. The fluctuations in the daily catch are also seen clearly.
3) The stations of the abundant nets and those of the poor ones in the catch are fixed. Generally, the catches are abundant in near shore nets around the islands, and poor in off-shore nets setting southwestern area of Hashiri-shima and Uji-shima. The beginning, the peak and the end in fishing are the same among them. Two patterns of the seasonal variations of near shore nets and off-shore nets, obtained from smoothing by the five-place moving averages of the catch, show about the same fluctuations.
4) It is noticed that the seasonal variation patterns of the catch by the nets are the two types. The one is the unimodal distribution and the other is the bimodal. It is considered that the difference of the patterns may be dependant on the environmental conditions of the fishing ground or the migrational and spawnig behavior of the fish.
1) Fishing of N. modestus are operated during the three months from April to June in this area and the most abundant catches are seen in May. About 95% of the catch is trapped by the masu-ami and about 5% is caught by the gill nets.
2) The annual catch of N. modestus shows considerably sharp fluctuation. The maximal catch during the seven years period is 40 metric tons in 1962, and the minimum is 3 metric tons in 1966. The fluctuations in the daily catch are also seen clearly.
3) The stations of the abundant nets and those of the poor ones in the catch are fixed. Generally, the catches are abundant in near shore nets around the islands, and poor in off-shore nets setting southwestern area of Hashiri-shima and Uji-shima. The beginning, the peak and the end in fishing are the same among them. Two patterns of the seasonal variations of near shore nets and off-shore nets, obtained from smoothing by the five-place moving averages of the catch, show about the same fluctuations.
4) It is noticed that the seasonal variation patterns of the catch by the nets are the two types. The one is the unimodal distribution and the other is the bimodal. It is considered that the difference of the patterns may be dependant on the environmental conditions of the fishing ground or the migrational and spawnig behavior of the fish.
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