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網の付着物に関する研究 予報 微細付着物の季節変動について


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Title: 網の付着物に関する研究 予報 微細付着物の季節変動について
Other Titles: Studies on the Attaching Materials on the Fishing Nets Preliminary. General Aspects on the Seasonal Variations of the Fine Attaching Materials.
Authors: 梶原, 武 / 飯塚, 昭二
Authors (alternative): Kazihara, Takesi / Iizuka, Syozi
Issue Date: 30-Nov-1959
Publisher: 長崎大学水産学部
Citation: 長崎大学水産学部研究報告, v.8, pp.43-50; 1959
Abstract: The fixed nets in shallow waters are covered all over by the fine attaching materials so called "Nuta" which consist of inorganic materials and micro-organisms (Diatoms, Cyanophyta and Protozoa etc), often within a short time after setting. Usually, fishermen operating the pound net in Omura Bay must clean and take up the net to dry at intervals of 7 or 10 days. If it were not for removing the fouling materials, the catches would be decreased and in the next stage the net become to be occupied by the fouling macro-organisms including algae, sea-squirts, tubeworms, bryozoas, mussels for more than a month. This study was undertaken from the aspect to elucidate the mechanism of fouling and ecological relations between the inorganic and organic materials. We surveyed the seasonal variations of the fine fouling materials in present report. The experiments were carried out at the station in Sakibe Inlet (Sasebo Bay) from January 1958 to July 1959. Samples were collected by the test nets illustrated in Fig. 1. Once a month usually, we hung down the new test nets, taking out the old nets simultaneously which had been laied during a month, two months and three months respectively in the sea. After removing the fine attaching materials and the fouling macro-organisms from each net, then the fine materials were strained through the large mesh sieve (1 mm. mesh) and small one (0.5mm. mesh). The fine muds passed through the small meshed were settled in the calibrated tubes and their volumes were recorded in cc. after 24 hours. Informations obtained from the experiments are as follows. The volumes of the fine muds in a month were small than them of 2 and 3 months. Generally, the fine muds of 5-7 m. depth nets increased slightly with the period which had been laied in the water, but muds of 0-4 m. depth nets were not so always. Also the mud volumes of surface nets were larger than the bottoms in spite of the duration of laying. In nets of the same period of laying, the seasonal variations of the fine muds in 0-3 m. depth nets were remarkable, in 4-7 m. depth nets were smooth. The seasonal variations of the fine muds in a month may be independent of rainfall and wind velocity of each month. / 1漁網(クレモナ網)に付着する泥について,'58年1月より'59年6月までに実験した結果について,二,三の知見を述べた。2泥の量は,網の浸漬期間が長期間になると共に,徐々に増加する。その際,表層の量は経月的な変動が大きいが,中層(4-5m層)以深ではほぼ直線的に増加している。3各月のとりあげた,同一期間浸漬網について,表層の網の泥の量は,季節的な変動が大きいが,中層(4-5m層)以深では変動が小さくなる。また短期間(1カ月間)の浸漬網では,水深別の泥の量の季節によるカーブは,表層から下層まで平行して動いているが,2カ月以上の浸漬網になると平行しなくな る。4一般に,浸漬期間の長短にかかわらず,表層ほど泥の量が大きく,深くなるにつれて減少している。52カ月網,3カ月網の各水深別の泥の量は,網を海に入れた月におけるよりも,とりあげた月の付着の状態により影響をうけている。6泥の付着量におよぼす,降水や風の影響はあきらかでない。
URI: http://hdl.handle.net/10069/31815
ISSN: 05471427
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:第8号

Citable URI : http://hdl.handle.net/10069/31815

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