| Takifugu obscurus commonly known as river puffer fish,belongs to Tetraodontiformes,Tetraodontidae,and Tikifugu.It is mainly distributed in Yellow Sea,the East China Sea and the middle and lower reaches of the Yangtze River and eproductive swimming habits in sea and freshwater.The juvenile of T.obscurus has fast growth speed,tender meat and high nutritional value.It is currently the main species of cultured river sturgeon in China.In recent years,due to environmental pollution,overfishing,and other reasons,the resources of the oriental sturgeon have continued to decline.Since 2000,some river sections have not been able to collect broodstock.The conservation and management of the oriental sturgeon resource is imminent.The way for the conservation and conservation of fishery resources is important for the restoration of the marine ecological environment.This article aims at the problem of how to screen the appropriate anesthetic and the appropriate labeling method during the release process of the T.obscurus.Effects of anesthesia effective mass concentration,anesthesia water temperature,and post-anaesthesia time on anesthesia effects of juveniles,the effects of anesthesia on the respiratory rate of juveniles,physiological and biochemical indexes such as enzymes and hormones in blood and liver,and T-bar mark experiments on the selection of the technology and the suitability of the marker site have conducted systematic studies on juveniles,which aims to provide basic data and technical support for the breeding and conservation of the T.obscurus1.Study on the anesthetic effect of MS-222 and eugenol on juvenile T.obscurusIn order to study the anesthetic effect of MS-222 and eugenol on juvenile T.obscurus,the juveniles with body weight of（71.37±3.24）g were selected for experiment.According to the main behavioral characteristics on anesthesia and resuscitation of juvenile T.obscurus,the anesthesia process was divided into six phases and the resuscitation process was divided into four phases.The results showed that the concentration of anesthetic is negatively related to the anesthesia time of juvenile and positively related to the recovery time.With the increase of the concentration of the two anesthetics,the anesthesia time of the juveniles was gradually shortened and the recovery time was gradually increased.When the concentrations of MS-222 and eugenol were in 60 mg·L-1 and 30 mg·L-1,the final anesthesia level can reach the anesthesia stage 6（medullary anesthesia period）.When the concentration of MS-222 is120～140 mg·L-1 and the concentration of eugenol is 60～70 mg·L-1,the juveniles can be anesthetized within 3 minutes and resuscitated within 5 minutes.Juvenile anesthesia time and resuscitation time are inversely related to anesthesia water temperature.With the increase of water temperature,the anesthesia time and recovery time of juvenile fish showed a decreasing trend.After the juvenile fish reached the 6th stage of anesthesia,before exposure for 5 minutes,the recovery time of juveniles gradually decreased with the increase of exposure time in the air,and the anesthesia effect was better.After exposure for 5 minutes,the recovery time of juveniles gradually increased.When exposed for 30 minutes,the recovery time of juveniles had exceeded 300 s;the recovery time of juvenile fish in the eugenol group continued to rise with the extension of exposure time.The recovery time after 2 minutes of exposure has exceeded 300 s.The recovery time of the recovery time after 6 minutes of exposure has accelerated.Over500 s,the survival rate of juveniles decreased to 80%when exposed for 20 minutes.The study believes that the MS-222 concentration of 120-140 mg·L-1 and the eugenol concentration of 60-70 mg·L-1 both have good anesthetic effects on juvenile puffer fish with short anesthesia time and resuscitation.The feature of fast,if you need to stay in the air for a long time in the process of proliferation and discharge marking,you can prefer to choose MS-222 as an anesthetic.2.Effects of MS-222 and eugenol on the physiological and biochemical indexes of juvenile T.obscurusIn order to investigate the changes of physiololgical and biochemical indexes of MS-222 and eugenol before and after anesthesia of juvenile T.obscurus,the quality of juvenile fish（93.37±4.12）g was selected at water temperature of（21.9±0.1）°C.Next,changes in respiratory frequency during anesthesia and resuscitation;the activities of blood cortisol and liver alanine aminotransferase（ALT）and aspartate transaminase（AST）in juvenile fish were determined before anesthesia,deep anesthesia and resuscitation for 1 h.The results showed that both MS-222 and eugenol could increase the respiratory rate of the juvenile larvae and then decrease.The respiratory rate of MS-222 group reached the highest in anesthesia stage 2,which was（198.75±2.58）times/min and the respiratory rate of the eugenol group was the highest in the anesthesia stage 1 which was（186.75±2.86）times/min.The respiratory rate of the juveniles in the two groups increased gradually during the recovery stage.Compared with the eugenol,the respiration of recovered 4 of the MS-222 group is closer to the pre-anesthetic level;MS-222 and eugenol have significant effects on the blood cortisol,liver alanine aminotransferase and aspartate aminotransferase content of juvenile fish（P<0.05）,the blood cortisol content of the young fish of the two groups of MS-222 and eugenol are under deep anesthesia The time was as high as（11.23±0.20）ng·mg-1 and（10.12±0.25）ng·mg-1,which was significantly higher than the pre-anesthesia level（6.48±0.26）ng·mg-1（P<0.05）,after recovery 1 h was reduced to（10.12±0.15）ng·mg-1 and（9.20±0.17）ng·mg-1,respectively,and neither recovered to pre-anesthesia levels.The blood cortisol content of juvenile fish in the eugenol group fluctuated more than in the MS-222 group Small;liver alanine aminotransferase content in the MS-222 and eugenol groups was as high as（32.25±0.23）U·g-1 and（25.66±0.59）U·g-1 during deep anesthesia,which was significantly higher than that of anesthesia Pre-level（19.05±0.97）U·g-1（P<0.05）,decreased to（27.24±0.58）U·g-1 and（24.62±1.52）U·g-1,respectively,after 1 h of recovery,but no recovery To the level before anesthesia;the liver aspartate aminotransferase content of the two groups of juveniles was as high as（18.44±1.98）U·g-1 and（17.22±1.66）U·g-1 during the deep anesthesia,which was significantly higher than the pre-anesthesia level（9.52±0.66）U·g-1（P<0.05）,respectively decreased to（14.78±1.56）U·g-1 and（13.22±1.33）U·g-1 did not return to pre-anesthesia levels.The activity fluctuations of alanine aminotransferase and aspartate aminotransferase in the liver of the young fish in the eugenol group were smaller than those in the MS-222 group.The study believes that in terms of physiological and biochemical indicators such as juvenile respiration rate,blood cortisol hormones,liver alanine and aspartate transaminase activity,eugenol is less harmful to juvenile fish and liver,and is more suitable for the production of juvenile puffer,Transportation and other fields.3.Study on T-bar marker technology and marker site suitability selection of juvenile T.obscurusIn order to improve the survival rate and marker recovery rate of T.obscurus,based on the study of anesthetics,experiments were conducted on the effects of different marking sites on the growth and feeding of T.obscurus.Three groups of juveniles were injected with T-shaped external suspension markers in the head and dorsal fin muscles（group A）,the dorsal and intercaudal fin muscles（group B）,and the anal and intercaudal fin muscles（group C）.Control group O was set,and the pros and cons of the marked part were evaluated based on indicators such as the difficulty of injection operation,the survival rate of the fish body,the rate of marker shedding,the growth rate of body length,the growth rate of body weight,the feeding rate,and specific growth rate.Study have shown that different marked locations have significant effects on the survival rate and off-standard rate of juveniles（P<0.05）.The survival rate of juvenile fish was O group>B group>C group>A group.The survival rate of the three groups A,B and C was significantly lower than that of the control group（P<0.05）,and the survival rate of group B was the highest（89.77±3.24）%;Out-of-standard rate group A=B group<C group,the out-of-standard rate of group C is significantly higher than that of groups A and B（P<0.05）,which is（6.82±0.44）%,during the 60-day breeding process It was found that 15～20 d was the peak period of marker shedding,after which the markers almost no longer shedding;different marker positions had a certain effect on the growth and feeding of juvenile puffer fish,total length growth rate group O>group B>group C>Group A,Group O and Group B have no significant difference（P>0.05）,significantly higher than Group A and Group C（P<0.05）,body mass growth rate Group O>Group B>Group A>Group C,O There was no significant difference between group B and group B（P>0.05）,which was significantly higher than that of group A and group C（P<0.05）.Significant difference（P>0.05）,significantly higher than group C（P<0.05）,specific growth rate group O>group B>group A>group C,no significant difference between group O and group B（P>0.05）,significantly higher than Group A and Group C（P<0.05）.In summary,the markers should be injected into the B site,that is,the muscles between the dorsal and caudal finsduring the proliferation and release of the juvenile puffer fish.At the same time,in order to miss the peak of the mark drop and increase the mark catch rate,it is necessary to temporarily raise 15-20 d... |
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