Analysis Of Hearing Characteristics Of Fish By Using Electrocardiogram

In recent years,with the recent decrease in fishery resources,the hearing capacities of fish have been studied through ambient noise assessment by using acoustic domestication for the protection of fish and the construction of marine ranching.Electrocardiogram(ECG)is used to observe fish hearing capacities.Encompassing behavioral and electrophysiology science,this method is based on a condition reflex reaction by acoustic and electrical stimulus and is used to monitor the hearing threshold through the heart rate characteristics of fish.Paralichthys olivacues is a bottom-living fish without swimming bladder which is a mainly commercial species in northern China.The auditory sensor organs of Paralichthys olivacues are the otolith and the lateral line.This study object is to use ECG method to measure the hearing threshold of Paralichthys olivacues by self-established fish auditory sensation measuring devices,in order to analysis the hearing capacities of Paralichthys olivacues and to provide reference for developing and construction of the marine ranching in China.The acoustic stimulus frequencies of the study are set up as follow:60 Hz,100 Hz,150 Hz,200 Hz,300 Hz,400 Hz,500 Hz and 700 Hz,for measuring the hearing threshold of 20 ind fish,and then the audiogram could be drawn and analyzed.Before the experiment,an acoustic and electoral stimulus conditioned reflex in the fish should be established to make sure the fish could develop memory from the stimulus,and then the hearing thresholds could be estimated using by the heart rate characteristics of fish which are recording by a silvery insulted wire in the fish heart.The ECG signal of 20 ind fish have all been obtained and the results are as follow:The hearing sensitive frequency bandwidth of Paralichthys olivacues is from 60 Hz to200 Hz and the hearing threshold is below 136 dB(re: 1?Pa),and in 100 Hz is the most sensitive frequency bandwidth and the hearing threshold is 94 dB.The hearing threshold of Paralichthys olivacues is quite similar to the Limanada limanada which have same body shape,they sensitive to the acoustic stimulus in 60 ~ 200 Hz frequency bandwidth.Hexagrammos otakii is a reef fish without a swim bladder and is mainly commercialized in northern China.The auditory sensor organs of Hexagrammos otakii are the otolith and lateral line.This study aims to apply ECG to measure the hearing threshold of Hexagrammos otakii by using self-established fish auditory sensation measuring devices,analyze the hearing capacities of Hexagrammos otakii,and provide reference for the development and construction of marine ranching in China.The acoustic stimulus frequencies in this study are at 60,100,150,200,300,400,500,700,and 1000 Hz for measuring the hearing threshold of 20 individual fish.Audiogram was then drawn and analyzed.Before the experiment,an acoustic and electrical stimulus conditioned reflex in the fish was established to ensure that the fish could develop memory from the stimulus.The hearing thresholds were estimatedusing the fish heart rate characteristics,which are recorded by a silver-insulated wire placed in the fish heart.The ECG signals of 20 individual fish were obtained.The hearing-sensitive frequency bandwidth of Hexagrammos otakii is from 60 Hz to 500 Hz,and the hearing threshold is below 131 dB.The most sensitive frequency bandwidth is 150 Hz,and the hearing threshold is 96 dB.The advantage of ECG method is that it could obtain a stable signal,and the fish exhibit conditioned response to the acoustic stimulus.The hearing threshold of Hexagrammos otakii is similar to that of Theragra chalcogramma.Both species have the same body shape and are sensitive to the acoustic stimulus in 60–500 Hz frequency bandwidth.The advantage of ECG method is that it could obtain a stable signal,and the subject fish show obvious conditioned response to the acoustic stimulus.Moreover,the trauma to the fish is much less,it could recover soon to do the repeated test.The results of the study could help us to promote the fundamental research in fish auditory sensation,and provide reference for the construction in marine ranching,and also for developing the new tape of fishing net by acoustic method in the future.The results of this study could help us promote the fundamental research in fish auditory sensation,provide reference for the construction of marine ranching,and develop new type of fishing net by using the acoustic method in the future.