Study On Sound Scape Of Fish Habitat In Marine Ranch Demonstration Area

The construction of marine ranch can increase and conserve fishery resources,improve the ecological environment of the sea area,and realize the sustainable utilization of fishery resources.In recent years,the construction of acoustic domesticated marine ranch realized by using"artificial soundscape"technology has developed rapidly,which is of great significance to the proliferation and protection of fishery resources,the protection of marine environment and the sustainable development of fisheries.However,due to the influence of anthropogenic activities,the variation of offshore underwater environmental noise is complex,and there are relatively few studies on the underwater acoustic environment of marine ranch.Sebastes schlegeli,as one of the main stock enhancement and releasing fish species in the northern acoustic domesticated marine ranch,the study of its biological sound can better grasp its behavioral characteristics and help to explore the formation mechanism of fish shoals.Taking Sebastes schlegeli as an example,this paper carried out a study on the acoustic environment of fish habitat in marine ranch,in order to clarify the main noise sources of underwater environmental noise in marine ranch,extract the biological noise spectrum characteristics of Sebastes schlegeli,calculate the resonance hazard frequency of fish body,as well as the setting of acoustic domestication parameters and effective range of action.The main experimental results are as follows:1.Investigation and analysis on soundscape of fish habitat in marine ranch demonstration areaUsing passive acoustic monitoring technology,using Japanese AQH hydrophone(sensitivity:-193 d B re 1VμPa^-1,Japan)to independently construct underwater environmental noise measurement system to carry out marine environmental noise measurement in the marine ranch demonstration area.The results show that the noise lower than 100 Hz in marine ranch demonstration area is mainly ocean current noise;the frequency at about 1000 Hz is the noise of wind-induced bubbles and waves.The background noise from 1 m to 10 m underwater had no significant change,which is about 115 d B（P>0.05）.2.Extraction and analysis of biological noise of Sebastes schlegeliWith the combination of video monitoring technology and passive acoustic monitoring technology,the biological noise information of Sebastes schlegeli with a body length of 22.44±0.90 cm under the condition of indoor culture environment were completely obtained.The results show that:（1）The main frequency band of feeding noise is 2000～4500 Hz,and the sound pressure level is 96.53±0.65 d B;the main frequency band of swimming noise is 25～400 Hz,and the sound pressure level is 95.63±0.38 d B;the main frequency band of fish tail slapping water surface noise is 500～700 Hz,and the sound pressure level is 97.34±4.91 d B;the main frequency band of biological noise is 80～315 Hz,and the sound pressure level is 95.32±0.12 d B.（2）The biological sound production of Sebastes schlegeli"goo goo goo"is composed of single pulse and continuous pulse.The average width of single pulse is 15.83±2.11 ms,and the average pulse interval is 175.63±67.01 ms.The average width of continuous pulse is 15.92±2.06 ms,and the average pulse interval is 161.57±22.69 ms.（3）Sebastes schlegeli is comparatively active in the period from 8:00 to 8:30,and there are more swimming noise and biological sound than those between 16:00 and 16:30.During the period from 16:00 to 16:30,the noise of the test fish’s tail slapping against the water surface was not collected,because the fish were not fed and all the test fish lived at the bottom of the tank for move freely.The results show that the spectrum characteristics of biological noise can feedback the behavior of Sebastes schlegeli,and provide data support for the collection of biological noise and behavior monitoring of Sebastes schlegeli in the field environment.3.Calculation of resonance hazard frequency of Sebastes schlegeliUsing the X-ray method,the volume of swim bladder of Sebastes schlegeli with different body length was measured,the curves of body length,body mass and swim bladder volume were fitted,and the resonance frequency of swim bladder was calculated and analyzed,the resonance hazard frequency characteristics of Sebastes schlegeli with different body length were determined and quantified.The results shows that the resonance frequency of swim bladder of Sebastes schlegeli with body length of 21.74±0.32 cm is 552 Hz;The resonance frequency of the bladder of Sebastes schlegeli with a body length of 23.76±0.62 cm is 505 Hz;The resonance frequency of the swim bladder of Sebastes schlegeli with a body length of 28.11±0.54 cm is 417 Hz.The resonance frequency of the swim bladder of Sebastes schlegeli with different body length is different,and the resonance frequency decreases with the increase of body length.4.Measurement and analysis of effective range of sound domesticationThe function generator,power amplifier and underwater loudspeaker are used to construct the underwater sound reproduction system,and the sound reproduction parameter is 155 d B 300Hz sine wave.The underwater sound reproduction system is constructed,and the underwater noise measurement system is used to monitor the underwater noise.The results show that:（1）The attenuation models in the horizontal direction of 1 m,5 m and 10 m underwater are obtained as follows respectively:underwater 1 m:TL=1.73*10 log（r）;underwater 5 m:TL=1.58*10log（r）and underwater 10 m:TL=1.70*10 log（r）.The attenuation model basically conforms to the spherical attenuation law（attenuation coefficient N=2）.（2）The sound pressure level of underwater background noise at 300 Hz in the marine ranch demonstration area is about 75 d B,the sound pressure level of 300 Hz noise monitored at 250 m away from the sound release point is about 99 d B,which is about 25 d B higher than the background noise,while the sound pressure level of 300 Hz noise monitored at 500 m away from the sound release point is about 90 d B,which is about 15 d B higher than the background noise.The effective radius of sound domestication in the marine ranch demonstration area is 500 m.To sum up,taking Sebastes schlegeli as an example,analyzing the relationship between its biological noise information and its behavior,and carrying out the research on the soundscape of fish habitat in marine ranch can provide a scientific basis for controlling fish swarm actions,creating a modern marine fishery production mode with ecological health,environment-friendly and resource conservation,and optimizing and perfecting the construction of sound domesticated marine ranch in the future.