Preliminary Research On The Taming Technology Of3Typical Releasing Juvenile Fishes In Northern South China Sea

Ocean Ranch is a good habitat suitable for releasing organisms through theconstruction of ecological environment, reproduction releasing and transplantdischarge (such as discharge artificial reef area or algal reef, artificial upwelling). Inorder to management the ranch scientific and ultilize waters productivity and seaspace maximum to form a highly efficient artificial fisheries ground andimplementing a proliferation of marine ecosystem management of fisheries by usingthe technology of advanced fish control (such as sound, light, electricity, maqnetism,net, lure, air bubble curtain etc.) to assemble organism which were releasing byhuman and inhabited in waters.Acoustic tame and bubble curtain interceptiontechnology is currently most used in fish behavior control in the construction of oceanranch. Acoustic tame technology is based on the auditory characteristics of tamedobject, using the way of broadcasting sound combined with casting lure to buildconditioned reflex to sound before releasing and to the purposes of improve thesurvival rate of the discharge biological and pasture management. Bubble curtainintercept technology was to forma a wall of the bubble curtain which fish produceintercept by plumping a certain pressure of air through the snorkel with a certain poresize and pore distance. In recent years, China has vigorously promote the constructionof ocean ranch, but there was few research on the behavior control technology ofmain species in South China Sea which cannot meet the needs of the construction ofocean ranch. Fish acoustic tame technology and the bubble curtain interceptiontechnology in the South China Sea have not started yet.The research was carried out in the experimental tank which size is length5m,width4m, depth1.5m in laboratory and semi-open natural waters. Based on theresearches on the sensitivities of fishes to the sound with different frequencies, wechose5frequencies of rectangular continuant. The acoustic tame effect toChrysophrys major, Sparus macrocephlus, Trachinotus ovatus in laboratory and semi-open natural waters and the interception effect to Chrysophrys major, Sparusmacrocephlus, Trachinotus ovatus by12kinds of bubble curtain in laboratory werestudied.The main methods are as follows:1. The method of acoustic tame in laboratory: acoustic tame experimental wascontinuant for7to8days. From8:00to20:00to broadcasting sound for120scombined with casting lure every4hours, each feeding about0.6%heave of total fish.Broadcasting sound without casting lure for120s at22:00once a day, with referenceto the experimental group, casting lure without broadcasting sound in control group.We were using the monitoring system and the assistance of stopwatch to record thebehaviors of fish around10minutes while broadcasting sound in control group andtrial groups. The records include the reaction time, aggregation time, residence timeand aggregation ratio of fish.2. The method of acoustic tame in semi-open natural waters: discharge fishesinto semi-open natural waters which tamed for7days by the best frequency sound.Broadcast sound for30minutes in3days continuant to allure fishes and broadcastsound again20days later. We observed and recorded the time and number of fish thatpresent to the scope which related to the transparency of water. We set the underwateramplifier as the centre of the scope area with radius of3metres.3. The method of bubble curtain: bubble curtain experimental placed inflatabletube on the bottom of the pool midline, alternate sub-inflation and inflation(controlled group) of two parts, each part was30minutes. Control group was testbefore experimental group. Each experiment was repeated three times. We were usingmonitoring system to record the behaviors of fish and the time and number of fish thatfish cross the bubble curtain during the whole experimental process.The main results are as follows:1. Rectangular continuant at200Hz,300Hz,400Hz,500Hz,600Hz have obviousacoustic tame effect on Chrysophrys major, Sparus macrocephlus, Trachinotus ovatus.The best acoustic tame frequency for Chrysophrys major, Sparus macrocephlus,Trachinotus ovatus were200Hz、400Hz、300Hz respectively, the effect of acoustictame achieve the best after acoustic tame for4to5days of each frequency. Theindexes of acoustic tame effect of5frequencies to Chrysophrys major were52.86,52.34,44.49,36.88,51.68respectively. The order of acoustic tame to C. major was 200Hz,300Hz,600Hz,400Hz,500Hz. The indexes of acoustic tame effect of5frequencies to Sparus macrocephlus were45.03,45.33,55.44,34.58,49.79,respectively. The order of acoustic tame to S. macrocephlus was400Hz,600Hz,300Hz,200Hz,500Hz. The indexes of acoustic tame effect of5frequencies to Tovatus were37.71,48.63,40.21,32.70,41.53respectively. The order of acoustic tameto T. ovatus was300Hz,600Hz,400Hz,200Hz,500Hz.2. The results of acoustic tame using in semi-open natural waters showed that theaggregation rations were30.0%、26.7%、27.0%of juvenile C.major,30.0%、31.0%、29.0%of S. macrocephlus,35.0%、37.0%、36.0%of T. ovatus when broadcast soundfrom1stday to3rdday after discharge which was acoustic tamed for7days by themost effect frequency. The aggregation ratio was4.0%、5.0%、5.0%when broadcastsound after20days later.3. The results of the interception effect by12kinds of density bubble curtainshowed that when filling pressure was100L/min and water depth was0.7m, the bestinterception effect to the juvenile C.major, S. macrocephlus, T. ovatus were density ofthe air bubble curtainwith aperture of0.5mm and pitch of5.0cm, aperture of1.0mmpitch of2.5cm, aperture of1.0mm, pitch of5.0cm; interception rates were79.41%,79.39%,77.65%.This research confirmed the best acoustic tame frequency and the bestinterception bubble curtain of the juvenile C.major, S. macrocephlus, T. ovatus. Aswell as research, we developed new techniques and new equipments that suitable foracoustic tame in laboratory and nature waters which could provide a useful referencefor the South China Sea District, as well as our marine ranch building and research.China’s marine fish acclimation of a late start, there were quite distance to theconstruction of ocean ranching, fisheries reproduction and releasing, especially inSouth China Sea. The domestication of technology and equipment domesticationapplication technology still needs further study.