【作者】 杜浩；

【导师】 危起伟； 杨德国；

【作者基本信息】 华中农业大学 ， 渔业资源， 2005， 硕士

【摘要】 伴随着生长发育进程,美洲鲥仔鱼、幼鱼都表现出对闪光、噪声、人工操作、运输等明显的应激反应,使得仔鱼和幼鱼培育成活率很低。苗种分池及运输常导致高的死亡率而难以实现,从而成为美洲鲥规模化养殖和产业化的技术瓶颈。作者主要对美洲鲥幼鱼运输中应激反应机理和运输方法进行了初步研究。获得以下主要研究结果: 1 水温、水质、溶氧等是影响美洲鲥人工孵化和养殖的重要因子。最适孵化水温在17-20℃。水温大于23℃导致孵出苗大量死亡。地下水中重金属含量较高,受精卵的孵化率较低。仔鱼和幼鱼分别在DO<2.5mg/L和DO<3.2mg/L时出现缺氧致死。定期排污换水、保持清新水质和较高溶氧有利于生长发育。 2 早期仔鱼(20 Day-age前)暂养在孵化桶中高密度饵料和泡漩水下成活率较高。而后期死亡率较大。在水体较大的水泥池暂养的成活率一直都较高。 3 养殖过程中,美洲鲥表现出对噪音、闪光、人工操作等明显的应激反应,这是限制美洲鲥成活、生长和发育的主要因素。 4 MS-222、丁香油、苯唑卡因三种麻醉剂对美洲鲥幼鱼都有较明显的麻醉效果。较高的浓度会导致鱼停止呼吸甚至不能复苏,较低的浓度鱼体不能很好的进入麻醉状态。温度升高,麻醉效果增强。不同规格的鱼的麻醉效果相似。一定盐度对运输应激有一定的缓解。适合于美洲鲥转运的麻醉剂浓度为:MS-222,20-30mg/L;丁香油,8-10mg/L;苯唑卡因,20-30mg/L。 5 对美洲鲥麻醉和复苏状态下行为学观察表明,当美洲鲥转移到容积较小的方形、圆形容器中时,表现出冲撞容器壁的行为。不麻醉状态下转运到清水中4h后,鱼体血清皮质醇含量升高到原来的5-7倍。随着时间的持续,这种行为会导致美洲鲥体背变红、头部、眼睛及各鳍基部出血等现象,进而导致鱼死亡。这种行为将是影响美洲鲥长途运输难以实现的主要因素。使用麻醉剂进行分池、转运试验取得很好的效果,使2500尾鱼转运分池而成活率为100%。 6 用活鱼车和塑料袋充氧运输法将美洲鲥幼鱼从荆州运往武汉的长途运输试验表明,4h运输后,不加麻醉剂塑料袋充氧运输鱼全部死亡,加麻醉剂1尾/袋及5尾/袋运输鱼成活率分别为63.3%和56%,比活鱼车运输成活率(36.6%)高。活鱼车坚硬箱壁对鱼体的强烈冲撞是导致活鱼车运输成活率低的主要原因。基于此,设计了适用于活鱼车的理想的运输容器。更多还原

【Abstract】 With growth and development, the larvae and fingerlings showed obviously stressful to flash light, noise, handling, and transportation, which would cause the low survival rate and low growth rate in culture. Tank transference and long-distance transportation of fingerlings could hardly realized for the subsequent high mortality of the fish, which had became the bottlenecks in scale-cultivation and industrialization of the American shad. The author mainly studied on the transport stress and transport technology. Conclusions of the studies are as follows:1 Water temperature, water quality and dissolved oxygen (DO) were the important factors in incubation and culture of American shad. The suitable water temperature for incubation is between 17℃ and 20 ℃ and larvae died soon after hatch when the water temperature was above 23 ℃ . The Hatch rate in underground water with high concentration of the heavy metals was lower than in lake water. The larvae and fingerlings were observed died when the DO were below 2.5mg/L and 3.2mg/L respectively. Regular water exchanging and dirt cleaning, good water quality and high DO will make for better growth and development of American shad.2 Larvae in early stage(8-20 day-age) after hatch had high survival rates in the incubation barrel with the high density of plankton and turbulent current contrary to larvae in latter stage(20-33 days old). High survival rates were obtained in capacious tanks from larvae to fingerlings.3 Larvae and fingerlings of American shad were obviously stressful to flash light, noise, handling, and transporting, which were the main factors on limiting the survival, growth and development of the fish.4 MS-222, clove oil and bezuocaine had the same anaesthesia effect to American shad fingerlings, which would stop opercular movement in high concentrations and even could not be recovered, while could not be well anaesthetized in low concentration. The anaesthesia effects were enhanced in higher water temperature while were no obviously different with fish size. The concentration of MS-222 with 20-30mg/L, clove oil with 8-10mg/L and benzuocaine with 20-30mg/L were thought to be suitable for short or long distance transport.5 Behaviors of the American shad fingerlings in stages of anaesthesia or recovery were observed and the results showed that whether the fish were anaethetic or not, they collided with the container when they were transferred to smaller containers. Four hours later in fresh water, serum cortisol of the unanaesthetic fish increased 5-7 times higher than the initial lever. With the time went on, the blue-green back of the fish would got red and the head, eyes and the base of the each fims of the fish would hemorrhage and then the fish would die. So, this behavior would caused the failure in long distance transport ofthe fish. Short distance transference of the fish with anaethetics between the tanks were successfully realized. The 2500 fingerlings were successfully distributed to 10 tanks with 100% survivial rate.6 Long distance transport of the American shad fingerlings from Jingzhou to wuhan were conducted with plastic container by truck(PCT) and live-fish carrying truck(LFCT). The results showed that fish transported with no anaethetic were all died and the survival rate of the fish transported with PCT with 1 fish/bag and 5 fish/bags were 63.3% and 56% respectively, higher than that transported with LFCT(36.6%). It was the colliding of hard carriage wall with the fish that caused the failure in transport with LFCT. Follow this, the author designed the ideal container for the long distance transportation with LFCT.7 hi order to understand the mechanism of the high mortality in transportation, we investigated the changes of hormonal (cortisol) and blood biochemical parameters in 1+ year old American shad fingerlings with unstressed fish before transport (Initial-fish), fish after 2 hrs transport without anesthetics (I-fish) and fish after 2 hrs transport with 20mg/L anesthetic benzocaine (BZ-fish). The results showed that the serum cortisol and blood biochemical parameters were obviously changed after transportation. The serum cortisol in I-fish and BZ-fish are obviously higher than in Initial-fish and serum cortisol in I-fish was alse obviously higher than BZ-fish (p<0.05). The concentrations of serum TP, AP, AKP, CHE, ALT, K+ and Ca2+ in I-fish were obviously higher but values of AP/GP and AST/ALT were obviously lower than in Initial-fish(p<0.05). No significant difference of the blood biochemical parameters mentioned above were observed between BZ-fish and Initial-fish. The concentrations of serum LDH and AST in I-fish and BZ-fish were no obviously higher than Initial-fish (P>0.05) The concentrations of serum y-GT> GLLU TCn TG in I-fish showed no significant difference with Initial-fish but were obviously different to BZ-fish (p<0.05). The results also showed that the anesthetic benzuocaine had catabatic effect to the transport stress.8. Serum cortisol hi fingerlings after 2hrs transport with 20mg/L MS-222 or 10 mg/L clove oil with 10%o NaCl were obviously lower than that without NaCl(p<0.05) and it was not different after 2hrs transportation with 20 mg/L benzuocaine with or without l%NaCl.The results showed that NaCl also had catabatic effect to the transport stress. More proofs were required.更多还原