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漁船および網漁具の操業中に発する水中騒音について


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Title: 漁船および網漁具の操業中に発する水中騒音について
Other Titles: On the Underwater Noise from Fishing Boats and Netting Gear in Course of Fishing Operation
Authors: 西ノ首, 英之
Authors (alternative): Nishinokubi, Hideyuki
Issue Date: Aug-1970
Publisher: 長崎大学水産学部
Citation: 長崎大学水産学部研究報告, v.29, pp.91-102; 1970
Abstract: Resently, investigation has been made into the relationship between underwater noises and fish catches and into the fishing method using sounds. As one of the fundamental problems on these subjects, it is necessary to clarify the acoustical features of the noises in the spaces where fishes are distributed, for example, the frequency distribution and the sound pressure of the underwater noises which are made by fishing boats and gear. Therefore the author has measured by the aid of the underwater tape-recorder the underwater noises in course of the fishing operation with the one-boat type trawl net, the bull trawl net, and the purse seine. The analytical results of the measurement are as follows: 1) The underwater noises measured in fishing with the three types of fishing gear were different from one another. The noise from the one-boat type trawl net was pulsating, whereas that from the bull trawl net was almost continuous. The noise from the purse seine was also continuous being similar to that from the bull trawl net, though its frequency band was narrower than that for both types of trawl nets. 2) The frequency distribution of the noise was DC to 5000 Hz in the case of both trawl nets, and DC to 3000Hz in the case of the purse seine. The most predominant frequencies in these ranges were 500Hz to 800Hz in the case of the one-boat type trawl net, and 400Hz to 600Hz, somewhat lower though not so remarkable, in the case of the bull trawl net. In the case of the purse seine, on the other hand, any especially predominant frequency was not seen, but its peculiar noise of 5400Hz to 6000Hz caused by the friction of the purse ring against the purse wire was perceived in bracing the sinker side. 3) The acoustic comparison of the noises in fishing among the three type of netting gear showed that the engine noise was inaudible in the case of the one-boat type trawl net because of other noise, but was clearly perceived in the cases of the bull trawl net and the purse seine. 4) concerning the fish catch with the one-boat type trawl net in the East China Sea, the weight compositions of several useful species such as the drums (sciaenid fishes) were investigated. From the mean weight the resonance frequency of the air bladder was calculated and was revealed to almost correspond with the predominant frequency of the underwater noises given forth by the netting gear. In consequence, it is well considered that these underwater noise have significant influences on the perception and behavior of fish. / トロール網,以西底曳網および旋網の操業中の水中騒音を録音分析し以下に示す結果を得た. 1) 測定を行なった両底曳網の水中騒音はトロール網の場合はパルス状であるのに対し以西底曳網はほとんど連続音であった.旋網の場合は漁法上浮網形態で主に表層近くで用いられ網の海底との摩擦が少ないためエンジンノイズ,プロペラノイズが主でパターンとしては以西底曳網に似た連続音が主であった. 2) 周波数分布は両底曳網ではDC~5000Hz,またはそれ以上広帯域におよんでおり,旋網の場合はDC~3000Hzと両底曳網より狭い帯域範囲であった.また最も優勢な周波数はトロール網では500Hz~800Hz(最大37dB),以西底曳網はトロール網ほど顕著ではないが400Hz~600Hz(最大30dB),旋網に関しては優勢な周波数は認められなかった.しかし旋網特異の騒音として環と締括綱との網裾をしぼる時に摩擦音が5400Hz~6000Hzの周波数帯域において確認された. 3) 録音の再生時における聴覚による比較では,トロール網の場合,自船のエンジンノイズは他の騒音が大きく認められなかった.これに反し以西底曳網の方はハイドロホンまでの自船からの水平距離がトロール網のそれの約2倍にもかかわらず明らかにエンジンノイズを認める事ができた.旋網の騒音は集魚中,投揚網中共にエンジンノイズとプロペラノイズがほとんど全ての騒音であった. 4) 東支那海におけるトロール網の漁獲物中よりグチ,ニベ等有用魚種数種類の体重組成を測定し,その平均体重より「うきぶくろ」の共振周波数を算出した結果,網漁具の発する水中騒音の優勢な周波数とがほぼ一致した.この事から操業中の水中騒音が魚に対する知覚行動反応に有意的な影響を与えている事は充分考えられる.
URI: http://hdl.handle.net/10069/31199
ISSN: 05471427
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:第29号

Citable URI : http://hdl.handle.net/10069/31199

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