Study On The Effect Of Underwater Blasting Sound Waves On The Four Major Fishes

In order to meet the development of shipping economy,a series of waterway construction activities need to be carried out.There are many rapids and shallows on the trunk line of the upper reaches of the Yangtze River,especially in the upper reaches of the Yangtze River.Blasting construction in the channel will inevitably have a certain impact on fish in the Yangtze River.At present,researchers have found that sound may cause changes in fish behavior,speed,and physiological changes,but underwater blasting sound waves will specifically cause four major home fish.It is not clear what the impact is,and there is no safety critical range for fish impacts.Therefore,this article is mainly based on on-site measurement,numerical analysis and indoor experiments.Based on the analysis of underwater blasting sound signals and the auditory threshold of the four major home fishes,this article discusses the effects of underwater blasting sound signals on fish behavior and speed,with a view to There is a general understanding of the effects of underwater blasting sound signals on the four major major fishes.The results of the research are as follows.The waveform data of 138,28,56,66 kg explosives were measured at the blasting site.The duration of underwater blasting sound signal was about 0.3s,and the highest sound pressure level was about 250 d B.At the moment of blasting,each frequency band has a higher sound pressure level,but the main sound pressure level is concentrated in the low frequency.Within 10 k Hz,the underwater explosion sound signal attenuates relatively fast,and in the range of 10 k Hz～25k Hz,the underwater explosion sound signal attenuates relatively slowly.The energy of underwater blasting sound signal is highest in the frequency range of 689.06-1378.13 Hz.The proportions of energy below1378.13 Hz are 57.9%,69.2%,80.7%,and 75.3%,respectively,indicating that underwater explosion sound energy is mainly distributed in the area below 1378 Hz.Use auditory neurophysiological workstation(TDT for short)to collect the EEG signal waveforms of herring under different frequencies and sound intensities.It is found that the herring has a large change in brain signal waveform in the sensitive frequency range(100-500Hz).At the same frequency,the greater the sound pressure,the greater the waveform amplitude.In the end,the herring’s hearing threshold is 82 d B,and the most sensitive frequency is 500 Hz.By comparison,it is found that the sensitive frequencies of the four major home fish are distributed within 1500 Hz,and they can perceive sounds above 75 d B.It is preliminarily judged that underwater blasting may cause behavioral responses and hearing threshold shifts of the four major home fishes.When the sound pressure level is greater than 210 d B,it has a significant impact on fish behavior.Herring,grass carp,and silver carp show obvious curvature and scurry around away from the sound source,while bighead carp scurry around in a small area first,and then the fish schools are close together,the density of the fish schools increases significantly,and they tend to stay more.In situ.When the sound pressure level is greater than 210 d B,it has a significant impact on the speed.Herring,grass carp,silver carp,and bighead carp all appear to have speed peaks,the maximum speed distribution is wider,and the amplitude increases significantly,but this speed increases temporarily and lasts for a short time.The sound pressure level has an exponential positive correlation with the mean velocity.On the whole,underwater blasting within a certain range will obviously affect the normal daily activities of fishes,especially when the blasting is close to the habitat of the four major home fishes,it will cause obvious avoidance behaviors of fishes,but if it exceeds a certain range,The impact on fish is small.