The Behavior Response And Attractive Mechanism Of Larimichthys Crocea To Acoustic Stimulus

Biological noises of fish were included: swimming noises,fish bioacoustics and feeding noises.They were important sound information to fish in navigation,location,and also in acoustic communication for individuals,spouses,descendants and other companions.Large yellow croaker(Larimichthys crocea)was one of the sciaenidae family and was known to sound production.It was one of the major commercial fish in China with high economic and cultural value.At present the research on biological noises were mainly includes: acoustic locating fish,acoustic trapping in fishing,assessing ambient sea noises,and feedback the fish feeding status of indoor aquaculture.The study of the biological noises of Larimichthys crocea was mainly focused on the acoustic spectrum and acoustic exposure experiments.However,some study fields were still not clear.Such as the effects of soundscape and bioacoustics on auditory characteristics of the Larimichthys crocea,the relationship between the swimming speed and the behavioral response with different acoustic stimulation condition,and also in comparison of attract effect biological noises to artificial pure tone.Due to overfish in Larimichthys crocea,Chinese govern carried out the study on release and enhancement and culture and propagation to supplement resources stock for Larimichthys crocea.But there were still some problems as followed:(1)recapture rate of tagging and releasing was quite low,lead to the lack of population information by enhancement and releasing.(2)Baits waste in cage-culture was cause serious water environment pollution,high risk in disease outbreaks and the quality of fish was low.(3)It was hard to monitoring and management of fish behavior in deep sea cage-culture,and also hard to control food supply,there were lead to high cost and safety risks in offshore operational.In order to solve the above problems,the hypotheses of this study were built on that the biological noise of Larimichthys crocea could feedback its fish behavior;The auditory characteristics of Larimichthys crocea were consistent with the frequency of its bioacoustics and behaviors.The biological noises could attack Larimichthys crocea directly without food domestication.Based on these assumptions,the research contents and methods of this paper were as follows:(1)The passive acoustic monitoring(PAM)technique was the used to obtain the biological noises spectrum of Larimichthys crocea in different culture environment with different feeding supply modes,it concluded that the biological noises of Larimichthys crocea can feedback its behavior.(2)ABR technology was used to study the auditory characteristics of Larimichthys crocea,it confirmed that it was consistent with its bioacoustics frequency;(3)Behavior method and principal component analysis technique were both used to analyze the behavioral responses and attractive effects of Larimichthys crocea with biological noise and 500 Hz pure tone.The pixel vector displacement method was used to calculate the large number of fish and the relationship between the behavior responses and swimming speed of the Larimichthys crocea was analyzed.Finally,the reason and mechanism of the behavioral r esponse to acoustics attraction were explained.The main results were as follows: 1.Underwater sound and behavioral response of Larimichthys crocea in cage-cultureThe relationship between the underwater sound of cage-culture and the daily feeding and activity status of Larimichthys crocea was studied by using PAM technique.The biological noises of feeding supply by meat from 17~20 cm body length of Larimichthys crocea was record.The results showed that: The results showed that:(1)The underwater sounds around the cages were from the natural enviro nment noise(wind and breaking wave,500 Hz~24 kHz),the biological noises of Larimichthys crocea(disturbance calls frequency peak was at 630 Hz and feeding calls was at 800 Hz,swimming noise frequency bandwidth was in 50~ 400 Hz and feeding sound was in 20~2200 Hz),and anthropogenic noise(boat noise was in 50~500 Hz).(2)The SPL of ship noise(87.68 dB: re 1μPa)was not affect the sounds communication(98.83~101.11 d B)and feeding behaviors of the fish.(3)The SPL in the cages were the disturbance state>feeding state>background noise.These results concluded that the dominate fr equency peak and SPL intensity of the biological noise were connected with the Larimichthys crocea behaviors,the more reaction they were,the higher the SPL was,but the lower the dominate frequency peak was.Therefore,this study can be applied to mo nitor the biological noises of Larimichthys crocea to feedback their behaviors in cage-culture by PAM technique.2.Underwater sound measurement and analysis of indoor aquaculture of Larimichthys croceaThe relationship between aquaculture environment noises and biological noise was analyzed by using PAM technique.The feeding sound of pellet feed by 8~9 cm body length Larimichthys crocea was record.The results showed that:(1)The SPL of the aquaculture ambient noise was about 110.27 d B,they were mainly from the aquaculture facilities working sounds in the low frequency bandwidth(100 Hz),surface bubbling sounds(1250 Hz),the air-stones,air compressor and aeration facility working sounds in the high frequency bandwidth(1600~2500 Hz);(2)When the aeration and air-stone turned off,the SPL of the Larimichthys crocea feeding sound was about 92.65 d B,they were swimming noise(70~500 Hz),water surface agitation and bubble burst sounds produced by swallowing(1000~2000 Hz),chewing pellet feeds sound(2000~ 4500 Hz);(3)When the aeration and air-stone turned on,the SPL of the aquaculture ambient noise was 17.62 d B higher than the feeding sounds and could not be distinguished,but the feeding behavior of the fish was not affected.It was indicated that when the air aeration turned off the feeding sounds of Larimichthys crocea could feedback the its feeding state in indoor aquaculture.3.Study on the auditory characteristics of Larimichthys croceaABR technique was used to obtain the ABR waveform from 10 ind of Larimichthys crocea with body length of 17~20 cm.The results showed that:(1)At the same frequency,the incubation period of ABR waveform of Larimichthys crocea was prolonged with the decrease of SPL,and increased by about 0.8~1.2 ms with 6 dB turned down each time,and the amplitude of the waveform was weakened.(2)The hearing sensitive graph was "V" sharp.The auditory threshold was gradually decreased(about 100~96 d B)at 100~300 Hz,and the most sensitive frequency range(about 93~95 dB)was reached at 500~800 Hz,and the most sensitive auditory threshold frequency was 500 Hz(About 93 dB).At 1000~4000 Hz,the auditory sensitivity was significantly decreased and the auditory threshold was increased(about 97~120 dB).The results showed that the hearing frequency of Larimichthys crocea was consistent with its frequency of bioacoustics,which was significance in acoustic communication.The study of the auditory ability of Larimichthys crocea could help us to better understand the response thresholds to the acoustics stimulate,and provide the data reference for selecting the appropriate acoustic stimulation frequency and sound pressure level for the acoustic attract Larimichthys crocea.4.Acoustic attract experiment of Larimichthys croceaBehavioral method and PCA(principal component analysis)technique was using to analyze acoustic attract experiment in 40 ind adult fish group with body length of 17~20 cm,and 300 ind juvenile group with body length of 8~9 cm with no food supply during the experiment.And the average swimming speed was calculated based on "two-point method".Motion trails and fish numbers changes were described,and the pepsin activity changes as a physiological indicator were measured after the acoustic experiments.The results showed that:(1)the acoustic attractive effect of juvenile fish group was: feeding sound> feeding noise> 500 Hz pure tone.The best rate of feeding sound was about 93% ~ 97% and the attract time was about 18.4~25.8 s.The changes of pepsin activity were as follows: feeding sound group was increase about 11.84%(P <0.05),feeding noise group was increased by about 3.11%(P> 0.05),but 500 Hz was decreased by 12.06%(P <0.05).(2)In the adult fish group,the acoustic attract experiments were not significant(due to the soundscapes of environments were different),there were just changed the water layer to the top of the tank and feeding behavior were appeared.The number of these fish were about 26.3% in fish sound group,20% in 500 Hz pure tone,and the feeding noise was about 19.8%.After the acoustic stimulate experiments,the activity of pepsin in the biological noise group increased slightly(P> 0.05),and artificial pure tone group was also decreased a little(because of feeding models were different).(3)The relationship between swimming speed and behavior of Larimichthys crocea were about 1.1~1.9 LB·s-1 in foraging behavior,free cruise was about 3.3~4.1 LB·s-1,suddenly speed up behavior(compete food or avoidance reaction)was about 7.0~8.5 LB·s-1,the frightening escape was about 11.2~14.3 LB·s-1,and the kicking-gliding behavior was about 2.7~7.0 LB·s-1.The results showed that the biological noises of the feeding process of Larimichthys crocea had the effect of acoustic attract,which could activate the feeding behavior of Larimichthys crocea.In an appropriate sound pressure level(110~120 dB)range,if combination of food supply,it would be further improved the attractive rate and duration time.To sum up,the above results demonstrate d the hypotheses which were inferred in this paper.It explained the behavior response and attractive mechanism of Larimichthys crocea to acoustic stimulus,and the basic elements included that:(1)the auditory characteristics of Larimichthys crocea had different hearing sensitivity between low and high frequency bandwidth;(2)the intensicy(SPL)of acoustic stimulus should be appropriate;(3)the “soundscape” must be restored integrallty which could activate the feeding motivation of Larimichthys crocea.This paper was proved that acoustic attract by biological noises was a feasible method which were no harm to the fish,and able to feedback fish behavior,and also to activate feeding behavior of Larimichthys crocea.It could be applied to the fields of acoustic attractive fishing,concentrated feeding,and to supervision fish behaviors.It was confirmed that the auditory characteristics of Larimichthys crocea are consistent with their bioacoustics frequencies.It had reference value in ambient sea noise assessment and protection of hearing sensitive sciaenid fish.Due to the limited experimental conditions,the acoustic attract behavior experiment was performed in tank.In the future,we will continue to carry out relevant research work in study of biological noises in open sea area with acoustic guide fish,tagging and releasing,and add more experimental data in fields study.