【作者】 黄涛；

【导师】 侯杰；

【作者基本信息】 华中农业大学 ， 农业硕士（专业学位）， 2023， 硕士

【摘要】 网箱养殖是黄鳝（Monopterus albus）养殖的最主要方式,但依旧存在着养殖废弃物无法清除、箱内水环境易劣化和病害频发等诸多问题,制约了黄鳝产业的健康发展。因此,探索黄鳝绿色健康养殖新模式十分必要。池塘圈养模式作为一种新型的集约化循环水养殖模式,排污率大幅提高,固形废弃物排出率可达90%～95%,生态、经济和社会等综合效益全面提升。本研究探索了在圈养模式下,放养密度和隐蔽体对黄鳝生长的影响,旨在为建立黄鳝池塘圈养新模式提供基础资料。本研究选取规格较为一致的野生黄鳝为研究对象,平均初始体质量23.52±2.96 g,平均初始体长30.30±1.90 cm。设置低密度组850尾/圈（LSD,1.59 kg/m²）、中密度组1700尾/圈（MSD,3.18 kg/m²）与高密度组2550尾/圈（HSD,4.77 kg/m²）3个密度梯度,每个梯度3个重复,其中隐蔽体为空心莲子草（Alternanthera philoxeroides）;另外设置人工鳝巢组（FND）与空心莲子草组（WPD）2个不同的隐蔽体组,每组3个重复,放养密度为1.59 kg/m²。本试验养殖周期为90 d,定期测定黄鳝生长指标,血液生化、抗氧化性与非特异性免疫指标,以及水体理化指标,研究结果如下:1.圈养密度对黄鳝生长性能、生理机能及池塘水体质量的影响（1）不同圈养密度下,LSD、MSD和HSD组平均终末体质量分别为:69.39±4.49 g、60.48±4.32 g和52.45±2.81 g;整个养殖周期中,黄鳝终末体质量、增重率（WG）和特定生长率（SGR）均随着圈养密度的增大而显著性降低（P<0.05）,但不同密度组存活率（SR）无显著差异（P>0.05）;饲养45 d后,HSD组摄食率（FR）与饵料系数（FCR）均显著高于LSD组（P<0.05）;90 d时,LSD组丰满度（CF）显著大于HSD组（P<0.05）,但各密度组脏体指数（VSI）与肝体指数（HSI）无显著性差异（P>0.05）。（2）圈养密度对黄鳝血清中葡萄糖（Glu）与总蛋白（TP）无显著影响（P>0.05）;在养殖后期,黄鳝血清中总胆固醇（T-CHO）、碱性磷酸酶（ALP）含量随着养殖密度的增大而显著升高（P<0.05）,血清中甘油三酯（TG）、白蛋白（Alb）、谷草转氨酶（AST）水平,则表现为HSD组显著高于LSD组（P<0.05）,MSD组与LSD组之间无显著性差异;HSD组黄鳝血清中丙二醛（MDA）含量要显著高于LSD组（P<0.05）,而过氧化氢酶（CAT）、总超氧化物歧化酶（T-SOD）与溶菌酶（LZM）活性则显著低于LSD组（P<0.05）。（3）在圈养条件下,外塘水体温度变化速率比圈内水体更快,p H值与溶解氧（DO）远大于圈内;各密度组水体中温度与DO均无显著性差异（P>0.05）,但p H值随着养殖密度的升高而减小,且在多个时间点均表现出显著性差异;水体中氨氮（NH₄⁺-N）、亚硝态氮（NO₂^--N）、硝态氮（NO₃^--N）等水质理化指标均随着养殖密度的增加而上升,并且HSD组与LSD组差异显著（P<0.05）。2.隐蔽体对黄鳝生长性能、生理机能及池塘水体质量的影响（1）放苗阶段（0～15 d）,FND组SR显著低于WPD组（P<0.05）,但养殖阶段（15～90 d）,WPD组SR低于FND组;不同隐蔽体下,FND组与WPD组终末密度分别为2.90±0.6 kg/m²、2.93±0.7 kg/m²;整个养殖周期中,FND组黄鳝终末体质量与体长和WPD组无显著性差异（P>0.05）;在养殖周期的各个阶段中,两组间WG和SGR均无显著性差异（P>0.05）;在15～60 d阶段,FND组黄鳝FR要高于WPD组,但FCR无显著性差异（P>0.05）;两组VSI与HSI均无显著性差异（P>0.05）。（2）在圈养系统中,不同隐蔽体的两组黄鳝血清中TP、T-CHO、ALP、TG、ALB、AST水平均无显著差异（P>0.05）,并且两种隐蔽体对黄鳝血清中抗氧化与非特异性免疫指标均为无显著影响（P>0.05）。（3）不同隐蔽体下,两组水体中温度差异微小;FND组水体中p H值与DO均普遍高于WPD组,且在多个时间点具有差异性显著（P<0.05）;WPD组水体中NH₄⁺-N和NO₂^--N浓度显著低于FND组（P<0.05）,但WPD组水体中NO₃^--N溶度显著更高。综上所述,HSD组黄鳝生长性能受到抑制,水体中NH₄⁺-N、NO₂^--N等有害物质浓度显著增加,但经济效益显著高于LSD组;以空心莲子草与人工鳝巢作为隐蔽体,养殖效果无显著差异,但空心莲子草可吸收水体中NH₄⁺-N与NO₂^--N等有害物质,且廉价易得,有利于净化水质。综合考虑黄鳝养殖中的生长性能、经济效益及其生态效益,建议在池塘圈养黄鳝的实际生产中,将投放密度控制在LSD组与MSD组之间,1100～1300尾/圈为宜,优先选择空心莲子草为黄鳝隐蔽体。更多还原

【Abstract】 Cage culture has always been the main method for raising ricefield eel（Monopterus albus）,but it has led to many problems such as the inability to remove waste,deterioration of water quality inside the cage,and frequent occurrence of diseases,which have hindered the healthy development of ricefield eel farming.Therefore,it is necessary to explore new models for healthy ricefield eel farming.The Juanyang mode,as a new type of intensive and circular water farming model,has innovatively improved the sewage discharge rate and the solid waste discharge rate can reach 90%to 95%.The comprehensive benefits of ecology,economy,and society have been greatly improved.This study explored the effects of suitable density and hiding structures on ricefield eel pond culture,with the aim of providing basic data for establishing a new ricefield eel pond culture model.Wild ricefield eels with consistent specifications were selected as the research objects,with an average initial body weight of 23.52±2.96 g and an average initial body length of30.30±1.90 cm.Three density gradients were set up:the low-density group（LSD）with 850tails/circle（1.59 kg/m²）,the medium-density group（MSD）with 1700 tails/circle（3.18kg/m²）,and the high-density group（HSD）with 2550 tails/circle（4.77 kg/m²）.Each gradient had three replicates,with the hollow lotus grass（Alternanthera philoxeroides）as the hiding structure.In addition,two different hiding structure groups were set up:the artificial ricefield eel nest group（FND）and the hollow lotus grass group（WPD）,each with three replicates,with a stocking density of 1.59 kg/m².The experimental period was 90days,during which the growth index,blood biochemistry,antioxidant and non-specific immune index of the ricefield eels,as well as the physical and chemical indicators of the water were measured continuously.The results of the study are as follows:1.The effect of cage density on the growth performance,physiological function,and pond water quality of ricefield eels（1）Under different stocking densities,the average final body weights for LSD,MSD,and HSD groups were 69.39±4.49 g,60.48±4.32 g,and 52.45±2.81 g,respectively.Throughout the rearing period,the final body weight,weight gain rate（WG）,and specific growth rate（SGR）of ricefield eels decreased significantly with the increase of cage density（P<0.05）.The survival rate showed no significant difference among the different densities（P>0.05）.After 45 days,the feed intake rate（FR）and feed conversion ratio（FCR）of the HSD group were significantly higher than those of the LSD group（P<0.05）.At 90 days,the condition factor（CF）of the LSD group was significantly higher than that of the HSD group（P<0.05）,but there was no significant difference in the visceral index（VSI）and hepatic index（HSI）among the different densities（P>0.05）.（2）Cage density had no significant effect on the serum Glucose（Glu）and total protein（TP）levels of ricefield eels（P>0.05）.In the later stage of rearing,the total cholesterol（T-CHO）and alkaline phosphatase（ALP）levels in the serum of ricefield eels increased with the increase of cage density（P<0.05）,while the triglyceride（TG）,albumin（Alb）,and aspartate aminotransferase（AST）levels in the serum were significantly higher in the HSD group than in the low-density group（P<0.05）.For the antioxidant and non-specific immune performance of ricefield eels,the malondialdehyde（MDA）content in the serum of the HSD group was significantly higher than that of the LSD group（P<0.05）,while the activities of catalase（CAT）,superoxide dismutase（SOD）,and lysozyme（LZM）were significantly lower than those of the LSD group（P<0.05）.（3）Under stocking conditions,the temperature of the outer pond water changed faster than that inside the circle,and the p H and dissolved oxygen（DO）levels were much higher than those inside the circle.There were no significant differences in temperature（T）and dissolved oxygen（DO）among the density groups（P>0.05）,but the p H decreased with increasing stocking density,and there were significant differences at multiple time points.The physicochemical indicators of water quality,such as ammonia nitrogen（NH₄⁺-N）,nitrite nitrogen（NO₂^--N）,and nitrate nitrogen（NO₃^--N）,increased with increasing stocking density,and there we re significant differences between the HSD and LSD groups（P<0.05）.2.The effect of hiding structures on the growth performance,physiological function,and pond water quality of ricefield eels（1）During the stocking phase（0～15 days）,the survival rate of the FND group was significantly lower than that of the WPD group（P<0.05）,but during the rearing phase（15～90 days）,the survival rate of the WPD group was lower than that of the FND group.At different hiding structures,the final density of the FND and WPD groups was 2.90±0.6kg/m² and 2.93±0.7 kg/m²,respectively.Throughout the rearing period,there was no significant difference in the final body weight and length,as well as WG and SGR between the FND and WPD groups（P>0.05）.During the 15～60 days period,the FR of the FND group was higher than that of the WPD group,but there was no significant difference in FCR（P>0.05）.There was no significant difference in VSI and HSI between the two groups（P>0.05）.（2）In the cage culture system,at 45 days,the GLU content in the serum of the FND group was significantly higher than that of the WPD group（P<0.05）,but there was no significant difference at 90 days（P>0.05）.There was no significant difference in the serum levels of TP,T-CHO,ALP,TG,Alb,and AST between the two groups with different hiding structures（P>0.05）,and there was no significant effect on the antioxidant and non-specific immune performance of ricefield eels（P>0.05）.（3）At different hiding structures,there was little difference in water temperature between the two groups.The p H and DO in the water of the FND group were higher than those of the WPD group,and the difference was significant at multiple time points（P<0.05）.The NH₄⁺-N and NO₂^--N levels in the water of the WPD group were significantly lower than those of the FND group（P<0.05）,but the NO₃^--N level was significantly higher.In summary,the HSD group of ricefield eels showed physiological dysfunction and inhibited growth performance,with a significant increase in toxic substances such as NH₄⁺-N and NO₂^--N in the water,but the economic benefits were significantly higher than those of the LSD group.Using hollow lotus plants and artificial ricefield eel nests as hiding structures resulted in similar aquaculture performance,but hollow lotus plants can absorb harmful substances such as NH₄⁺-N and NO₂^--N in the water and are inexpensive and readily available,which is beneficial for water purification.Considering the growth performance,economic benefits,and ecological benefits of ricefield eel farming,it is recommended to control the stocking density between the LSD and MSD groups,with a density of 1100～1300 tails/cage.Preferentially choose hollow lotus plants as the hiding structures.更多还原