工厂化养殖密度对黄条鰤生长和生理特性的影响

养殖密度是水产养殖管理中一项非常重要的参数, 适宜的养殖密度能够降低养殖动物的应激胁迫水平, 促进其健康、快速生长。为探究黄条鰤(Seriola lalandi)在陆基工厂化养殖条件下的最适密度, 本研究对 1 龄黄条鰤 [(565.83±70.22) g]开展为期 60 d 的养殖实验, 共设置 10 尾/m³ (低密度组)、20 尾/m³ (中密度组)和 30 尾/m³ (高密度组) 3 个密度组。实验过程中测量并计算包括增重率、特定生长率、肥满度和肝体指数在内的生长指标, 并检测血液生理、血清生化、肝脏和肾脏组织的非特异性免疫酶活性等指标。结果表明, 中、高密度组黄条鰤的增重率、 特定生长率在第 60 天时均显著低于低密度组对应的数值(P＜0.05); 在 3 个密度组中, 低密度组的特定生长率在 60 d 时显著高于 30 d 的数值(P＜0.05), 中密度组的特定生长率在 60 d 与 30 d 之间差异不显著(P＞0.05), 高密度组的特定生长率在 60 d 时低于 30 d 的数值, 说明高密度养殖对黄条鰤的生长产生了的胁迫。整个实验过程中, 血清中肾上腺素和皮质醇等的含量在 30 d 和 60 d 时均随养殖密度的增加而显著升高(P＜0.05), 生长激素和类胰岛素生长因子 Ⅰ的含量呈相反趋势; 肝脏和肾脏中超氧化物歧化酶、溶菌酶、谷丙转氨酶、谷草转氨酶、酸性磷酸酶、碱性磷酸酶和丙酮酸激酶的活性在 30 d 和 60 d 时整体呈现随养殖密度的增加而显著升高的趋势(P＜0.05), 说明高密度养殖对黄条鰤的生理造成了胁迫。由此可见, 从生长、生理和生产实践角度综合评价, 中密度(20 尾/m³ )是 1 龄黄条鰤工厂化养殖的适宜密度, 相关研究结果将为黄条鰤工厂化养殖技术进一步完善提供参考。     

植物甾醇对克氏原螯虾生长消化、肠肝形态及抗氧化和免疫水平的影响

本研究旨在探究饲料中添加植物甾醇对克氏原螯虾(Procambarus clarkii)生长、消化、抗氧化、免疫及肠肝形态的影响。制备 5 组等氮等脂饲料, 分别为在基础饲料中添加 0% (CON)、0.10% (P1)、0.19% (P2)、0.38% (P3) 和 0.76% (P4)的植物甾醇, 对体均重为(9.37±0.02) g 的克氏原螯虾进行 6 周的养殖实验。结果显示, P1 和 P2 组的增重率、特定生长率显著高于 CON 组(P＜0.05), 且 P2 组实验虾的生长性能最佳。P3 组实验虾肠道蛋白酶活性显著高于 CON 组, 脂肪酶活性显著低于 CON 组(P＜0.05)。P1 组肝胰腺中酸性磷酸酶和碱性磷酸酶活性最高, P2 组血淋巴中酸性磷酸酶和碱性磷酸酶活性最高, 但与 CON 差异均不显著(P＞0.05)。随着植物甾醇添加水平提高, 肝胰腺和血淋巴总超氧化物歧化酶活性与过氧化氢酶活性呈上升趋势, 丙二醛含量呈下降趋势。相较 CON 组, P1 组肠道结构更加健康完整, 植物甾醇水平达到 0.19%及以上时, 克氏原螯虾的肝胰腺与肠道组织形态出现受损状态。 随着植物甾醇水平提高, 肝胰腺的 NF-κB 相对表达水平升高。P1 组 Hsp70 相对表达水平显著高于其他组(P＜0.05)。 研究表明, 本实验条件下添加 0.10%~0.19%植物甾醇可以促进克氏原螯虾的生长消化, 改善肠肝组织形态, 提高克氏原螯虾抗氧化和免疫能力。     

饲料中添加核苷酸对凡纳滨对虾幼虾生长、组织生化组成及非特异性免疫功能的影响

选用960尾初始体重为(0.43?0.01) g 的凡纳滨对虾,随机分为8组,分别投喂基础饲料和7种添加核苷酸混合物(mix-NT)的试验饲料,5种核苷酸(5′-腺苷酸∶5′-胞苷酸∶5′-尿苷酸二钠∶5′-肌苷酸二钠∶5′-鸟苷酸二钠)按照质量比为1∶1∶1∶1∶1(W/W)混合,添加量分别为0.1、0.2、0.4、0.6、0.8、1.0和1.2 g/kg 饲料,试验周期为5周。结果显示,当mixNT添加量为0.4 g/kg饲料时,凡纳滨对虾的增重率(WGR)、特定生长率(SGR)和摄食量(FI)显著高于对照组(P<0.05),饲料系数(FCR)比对照组降低5.5%(P>0.05)。0.6和1.0 g/kg mix-NT添加组的蛋白质沉积率(PDR)显著高于对照组(P<0.05)。试验组对虾存活率(SR)和肝胰指数(HSI)均不同程度的高于对照组,但差异不显著(P>0.05)。饲料中添加mix-NT对全虾粗脂肪、灰分含量的影响显著(P<0.05),各mix-NT添加组的全虾干物质和粗蛋白含量均高于对照组,但差异未达到显著水平(P>0.05)。肝胰腺RNA含量和总蛋白(TP)含量均随饲料中mix-NT添加量的增加而升高,其中0.2~1.0 g/kg组的肝胰腺RNA含量显著高于对照组(P<0.05),TP含量差异未达到显著水平(P>0.05);各mixNT添加组的肠道TP含量均显著高于对照组(P<0.05),0.4和0.6 g/kg组的肠道RNA量极显著高于对照组(P<0.01)。外源mix-NT显著降低血清尿酸(UA)含量(P<0.05),但对TP、谷丙转氨酶(GPT)、高密度脂蛋白(HDL)含量无显著影响(P>0.05)。当mix-NT添加量为1.2 g/kg 饲料时,血清中谷草转氨酶(GOt)活性显著性升高(P<0.05)。鳃和肌肉酚氧化酶(PO)活性均在0.4 g/kg组达到最大,其中0.1～0.6 g/kg 组的鳃PO活性显著高于对照组(P<0.05),而各组肌肉PO活性无显著差异(P>0.05)。凡纳滨对虾肝胰腺和血清中溶菌酶(LZM)活性随饲料中mix-NT添加量的增加而显著升高(P<0.05)。结果表明,饲料中添加一定量的5种核苷酸混合物能显著提高凡纳滨对虾幼虾的增重率、特定生长率、摄食量、蛋白质沉积率、全虾粗脂肪和灰分含量,一定程度提高全虾粗蛋白和肝胰腺总蛋白含量,显著增加肝胰腺RNA、肠道总蛋白和RNA含量,提高对虾的非特异性免疫功能。     

3种养殖鰤鱼消化相关酶活性的比较分析

为深入了解鰤鱼的消化生理特性,测定并比较分析了3种鰤鱼[高体鰤(Seriola dumerili)、黄条鰤(Seriola lalandi)、五条鰤(Seriola quinqueradiata)]的消化系统(胃、幽门盲囊、前肠、中肠、后肠和肝脏)中5种消化相关酶(胰蛋白酶、脂肪酶、淀粉酶、碱性磷酸酶和酸性磷酸酶)活性与组织分布特点。结果显示,3种鰤鱼中5种消化相关酶主要分布在幽门盲囊、肝脏和肠道中。3种鰤鱼胃组织中胃蛋白酶活性无差异。幽门盲囊中胰蛋白酶活性：黄条鰤>高体鰤>五条鰤(P<0.05),高体鰤肝脏组织中胰蛋白酶活性显著高于其他2种鰤鱼(P<0.05);胃、中肠、后肠组织中α-淀粉酶活性：五条鰤>黄条鰤>高体鰤(P<0.05),幽门盲囊、前肠组织中α-淀粉酶活性：黄条鰤>五条鰤>高体鰤(P<0.05);胃、幽门盲囊组织中脂肪酶活性：黄条鰤>五条鰤>高体鰤(P<0.05),前肠、后肠、肝脏中脂肪酶活性：五条鰤>黄条鰤>高体鰤(P<0.05);3种鰤鱼的酸、碱性磷酸酶活性组织分布趋势基本一致,其中,黄条鰤幽门盲囊组织中酸、碱性磷酸酶活性最高(P<0.05)。研究表明,3种鰤鱼消化相关酶活性的组织分布特点基本一致,幽门盲囊是5种酶作用的主要靶器官,除胰蛋白酶外,高体鰤其他4种酶活性均显著低于其他2种鰤鱼,黄条鰤幽门盲囊和肠道的5种酶活性显著偏高。结果可为揭示鰤属鱼类的消化生理特性、研制适宜鰤属鱼类消化特点和种特异性生长的高效专用配合饲料提供理论依据。     

饲料中添加硫酸锌对奥尼罗非鱼幼鱼生长合机体抗氧化功能的影响

试验以硫酸锌为锌源，评价不同锌水平对奥尼罗非鱼幼鱼（Oreochromis aureus♂×Oreochromis niloticus♀）生长和抗氧化能力的影响。体质量为(4.13±0.32)g罗非鱼随机分配在18个水族箱中，每箱20尾，每3个箱为1个处理组，分别以添加锌为0、20、40、80、160和320 mg•kg^-1的6种饲料投喂，日投喂率为鱼体重5%～9%。8周的试验结果表明：20mg•kg^-1锌饲料组的增重率和鱼体蛋白含量显著高于其它各组(P＜0.05)，蛋白质效率、饲料转化率也明显高于其它各组；全鱼脂肪含量随着饲料锌水平的升高而升高，但320mg•kg^-1锌饲料组降低；20mg•kg^-1锌饲料组，脊椎骨中锌离子浓度达到最大值且显著高于0mg•kg^-1锌饲料组(P＜0.05)；20mg•kg^-1与40mg•kg^-1锌饲料组的血液中红细胞数量显著高于其它各添加组(P＜0.05)，20mg•kg^-1锌饲料组的血液中血比容显著高于0mg•kg^-1组(P＜0.05)，与其它各组没有显著差异；肌肉中，硫代巴比妥酸反应产物(TBARS)(Thiobarbituricacid reactive substances)的量，锌为0mg•kg^-1饲料组显著高于其它各组(P＜0.05)。综上所述，饲料中锌添加量为20mg•kg-1饲料促进了罗非鱼生长，使鱼体抗氧化功能增强。     

小麦基础饲料添加木聚糖酶对尼罗罗非鱼肠道菌群的影响

以尼罗罗非鱼［体重(100.39±17.83) g］为实验对象,小麦基础饲料为对照,小麦基础饲料中分别添加不同水平的木聚糖酶(0.05%、0.10%、0.15%)作为实验饲料。每个处理设5个重复,每个重复放养40尾雄性尼罗罗非鱼。饱食投喂,饲养78 d后测定尼罗罗非鱼肠道细菌总量,并对需氧菌和厌氧菌进行鉴定,旨在研究木聚糖酶调控肠道菌群、促进尼罗罗非鱼生长的机理。结果表明,0.10%组和0.15%组前肠需氧菌数量显著低于对照组(P<0.05),0.05%组、0.10%组和0.15%组中肠需氧菌数量显著低于对照组(P<0.05)。实验组后肠需氧菌数量均显著低于对照组(P<0.05)。0.15%组前肠厌氧菌数量比对照组、0.05%组和0.10%组分别降低76.85%(P<0.05)、75.62%(P<0.05)、75.83%(P<0.05)。0.10%组和0.15%组中肠厌氧菌数量显著低于对照组和0.05%组(P<0.05)。0.05%组、0.10%组和0.15%组后肠厌氧菌数量分别比对照组降低13.13%(P>0.05)、48.30%(P<0.05)、60.62%(P<0.05)。小麦基础饲料中添加木聚糖酶,主要影响需氧菌Ent.,Bac.和厌氧菌Bact.,Bif.,Lac.的组成比例。0.05%组、0.10%组和0.15%组前肠Ent.比例较对照组分别降低13.16%(P>0.05)、29.61%(P<0.05)、49.34%(P<0.05)。实验组前肠Bac.比例显著高于对照组(P<0.05)。0.10%组和0.15%组中肠、后肠Bac.比例显著高于对照组(P<0.05)。0.15%组前肠Lac.比例显著高于对照组和0.05%组(P<0.05)。对照组前肠Bact.比例显著高于0.10%组和0.15%组(P<0.05)。实验组中肠Bif.组成比例较对照组有显著提高(P<0.05)。0.15%组中肠Lac.比例显著高于对照组和0.05%组(P<0.05)。0.10%组和0.15%组中肠Bact.比例较对照组明显下降(P<0.05)。本研究认为,小麦基础饲料中添加木聚糖酶,可以调控尼罗罗非鱼肠道菌群,降低肠道致病菌Ent.和Bact.的组成比例,提高有益菌Bac.,Bif.和Lac.的组成比例。     

光强和光谱对鳜摄食、生长及相关基因表达的影响

为了探讨光强和光谱对鳜(Sinioerca chautsi)行为、摄食和生长性能的影响, 对不同光强和光谱条件下养殖 8 周的鳜的摄食、生长进行观测，并检测相关基因的表达情况。对鳜摄食的影响研究发现, 光强在 10、25 和 50 lx 下时鳜的摄食比例较高, 显著高于 5、300 和 500 lx 组(P＜0.05); 不同光谱下, 在绿光条件下摄食比例最高(P＜0.05)。 光强和光谱条件对鳜生长的影响结果显示, 10 lx 的光强可以极大地改善鳜的生长, 该组中增重率、特定生长率都显著高于其他组(P＜0.05), 同时饲料系数显著降低(P＜0.05); 200 和 500 lx 条件下生长性能提升不显著(P＞0.05)。另外, 10 lx 光强下生长相关基因 igf1 在肌肉中的表达量显著高于其他组, 同时促食欲基因 npy 和 agrp 显著上调(P＜0.05), 抑食欲基因 cart 和 pomc 下调; 而在 200 和 500 lx 条件下, npy 和 agrp 表达水平与对照组相比不显著(P＞0.05), 500 lx 条件下 pomc 表达显著高于 10 和 200 lx 组(P＜0.05)。绿光组的增重率和特定生长率显著升高(P＜0.05), 观察到生长性能的改善。在红光条件下观察到了相反的结果, 增重率和特定生长率显著低于其他组(P＜0.05), 肝体比显著大于其他各组(P＜0.05)。此外, 红光和绿光组 igf1 在肝脏中的表达量显著高于蓝光组(P＜0.05)。促食欲基因 npy 表达在绿光组中显著升高(P＜0.05), agrp 在红光、绿光和蓝光组中的表达量均显著低于白光组(P＜0.05)。综上所述, 鳜更加偏好低光强和短波长的光, 并且在这种光照条件下摄食行为更加活跃且具有较好的生长性能。     

高脂日粮添加胆汁酸对大口黑鲈生长性能、脂代谢和胆汁酸代谢的调节作用

为探究胆汁酸对高脂饲料饲喂下大口黑鲈(Micropterus salmoides)生长生理、脂代谢和胆汁酸代谢的影响, 配制基础饲料(脂肪含量 10.6%, 对照组 C)、高脂饲料(脂肪含量 17.5%, 高脂组 HF)、高脂饲料+300 mg/kg 胆汁酸 (HFB1)、高脂饲料+600 mg/kg 胆汁酸(HFB2)、高脂饲料+900 mg/kg 胆汁酸(HFB3) 5 种试验饲料。将 750 尾大口黑鲈随机分为 5 组, 每个组设置 3 个平行缸, 每缸 50 尾, 进行 7 周养殖实验。结果表明: 高脂饲料显著降低大口黑鲈生长性能, 而添加胆汁酸后可改善高脂饲料对大口黑鲈生长的不利影响。饲喂高脂饲料组血浆和肝脏中甘油三酯 (TG)含量显著升高(P＜0.05)。添加胆汁酸后, 肝脏中 TG 含量显著降低(P＜0.05), 而血浆中 TG 含量在胆汁酸添加量为 900 mg/kg 时显著下降(P＜0.05)。肝脏和血浆中总胆酸(TBA)含量随着胆汁酸添加量的升高而显著增加(P＜0.05)。 胆汁酸添加量为 600 mg/kg 时, 肝脏中法尼醇 X 受体基因(fxr)表达量上调(P＜0.05), 胆汁酸合成和转运相关基因 (cyp7a1、bsep、asbt)均显著上调(P＜0.05)。同时对脂代谢相关基因表达进行检测, 发现 fxr 诱导 shp 的表达, 抑制肝脏中 srebp1 及脂肪合成相关基因(fas、acc2)的表达。此外, 胆汁酸增加肝脏中脂肪分解和 β 氧化相关基因(lpl、 hl、hsl、cpt1、acox1)的表达水平。综上所述, 高脂饲料中添加胆汁酸可改善大口黑鲈生长性能, 通过 FXR/SHP/ SREBP1 信号通路调节脂质代谢, 并促进胆汁酸合成和循环, 本研究为进一步研究胆汁酸在鱼类中的营养调控作用奠定了基础。     

不同循环投喂模式对半滑舌鳎的生长、体成分组成、代谢和能量收支的影响

研究了不同循环投喂模式对半滑舌鳎的生长、体成分组成、代谢和能量收支的影响。其中包括5个处理:C(对照组,实验过程中持续投喂);S2F4组(饥饿2 d,投喂4 d);S4F8组(饥饿4 d,投喂8 d);S8F16组(饥饿8 d,投喂16 d);S12F24组(饥饿12 d,投喂24 d),实验时间72 d。结果表明,对照组的特定生长率(SGR_w和SGR_e)显著高于循环投喂各组(P<0.05)。对照组和S2F4组半滑舌鳎幼鱼的末体重没有显著差异(P>0.05),并且均显著高于其它各组(P<0.05)。对照组半滑舌鳎幼鱼的消化率显著低于其它各组(P<0.05),而能量消化率与S12F24组没有显著差异(P>0.05),但显著低于其它3个处理组(P<0.05)。S4F8组半滑舌鳎幼鱼饲料转化率显著低于S12F24组(P<0.05),对照组饲料转化率低于S2F4组和S12F24组但没有显著差异(P>0.05)。对照组半滑舌鳎幼鱼的摄食率显著低于其它各组(P<0.05)。体成分组成中,蛋白含量随饥饿、投喂周期的延长而下降,S2F4组和对照组半滑舌鳎的蛋白含量没有显著差异(P>0.05)。S2F4组的耗氧率和排氨率均较低。对照组的摄食能显著高于其它各组(P<0.05),S2F4组的呼吸能占摄食能的比例显著高于对照组(P<0.05)。研究表明,半滑舌鳎幼鱼在循环投喂模式下,具有较强的补偿生长能力,S2F4组具有完全补偿生长能力;在较长的周期性饥饿条件下,半滑舌鳎幼鱼体内的蛋白质含量会受到显著影响。     

饲料中菜粕和棉粕的不同配比对异育银鲫生长性能、血浆生化指标和棉酚残留的影响

为考察不同菜粕和棉粕的水平组合对异育银鲫生长、饲料利用、血浆指标和棉酚残留的影响,配制了菜粕∶棉粕(菜粕与棉粕之和为60%)分别为5∶0、4∶1、3∶2、2∶3、1∶4和0∶5的6组试验饲料,投喂平均体重为5.6 g的异育银鲫8周。结果表明,随着饲料中棉粕含量升高和菜粕含量减少,异育银鲫的增重率、饲料效率、特定生长率呈现先上升后下降趋势,其中菜粕∶棉粕为3∶2组的鱼生长最佳,增重率和饲料系数分别为505.6%和1.33,具有最高的肥满度和最低肝体比;菜粕∶棉粕为5∶0组的鱼生长最差,增重率和饲料系数分别为430.1%和1.52,具有最低的肥满度和最高的肝体比。各组成活率,肌肉水分、粗蛋白、粗脂肪和粗灰分含量没有显著差异(P＞0.05)。菜粕∶棉粕为5∶0组鱼的血浆谷草转氨酶(AST)和谷丙转氨酶(ALT)活力相对于菜粕∶棉粕分别为3∶2和2∶3组显著增加(P＜0.05);菜粕∶棉粕为3∶2组鱼的血浆碱性磷酸酶活力在各组中最高(P＜0.05);血浆中总蛋白在各组间差异不明显(P＞0.05)。对异育银鲫肌肉和肝脏分析发现,游离棉酚含量随着饲料中棉粕含量的升高而升高(P＜0.05)。本研究表明,在配方中菜粕和棉粕总量为60%的情况下,菜粕∶棉粕为3∶2时异育银鲫的生长性能最佳,具有最高的增重率和最低的饲料系数,过高的菜粕或棉粕均会降低鱼体的生长性能,使鱼体血浆ALT和AST活力升高。     

Anguilla huangi Teng, Lin, and Tzeng, 2009, is a junior synonym of Anguilla luzonensis Watanabe, Aoyama, and Tsukamoto, 2009

Anguilla luzonensis and A. huangi were each described in 2009 using eels obtained from northern Luzon Island. We examined the taxonomic status of these two groups of eels using morphological and molecular genetic characters. There were no significant differences in two vertebrae counts between eels of A. luzonensis and A. huangi. Mitochondrial 16S ribosomal RNA and cytochrome b genes sequences were obtained and compared among 28 specimens of A. luzonensis, the holotypes of A. luzonensis and A. huangi, and one specimen of the other 15 anguillid species. The specimens of A. luzonensis exhibited almost identical sequences, including the holotype, with only a few site differences, and the genetic difference between the holotypes of A. luzonensis and A. huangi was within the range of differences of specimens of A. luzonensis. The other anguillid species were genetically very different from A. luzonensis and A. huangi, although A. interioris is a closely related species. It is clear that A. luzonensis and A. huangi are the same species, and according to the principle of priority in zoological nomenclature, A. luzonensis Watanabe, Aoyama, and Tsukamoto, 2009 is the valid species name, and A. huangi Teng, Lin, and Tzeng, 2009 is a junior synonym of A. luzonensis.     

Effect of Lead on Survival,Osmoregulation, and Histological Changes of the Gills of the White Shrimp,Litopenaeus vannamei,Boone, 1931

The purpose of this study was to evaluate the acute toxicity of lead for different life stages of shrimp, Litopenaeus vannamei, and to determine the effect of its sublethal concentrations on osmoregulatory capacity (OC) as well as the possible histological alteration in the gills of juvenile shrimp. The 24‐, 48‐, and 96‐h LC₅₀ values for lead to L. vannamei increased progressively with increasing life stage, from nauplii < zoeae < mysis < postlarvae < juvenile. After 15‐d exposure to 3.25, 6.50, and 9.75 mg Pb/L, the OC values of exposed shrimp were reduced by 39, 73, and 157%, respectively compared to control animals. Compared to controls, the lead concentrations in gill tissues increased significantly by 127,500, 137,500, and 141,000% in shrimps exposed to 3.25, 6.50, and 9.75 mg Pb/L, respectively. After lead exposure, hemocytic congestion in efferent vessels and multiple hyperplasia were observed in gill filaments, resulting in narrowed hemolymphatic lacuna. The histopathological effects increased with increasing Pb concentration.     

Age,growth, maturity and the overfishing of the iconic sciaenid,Argyrosomus japonicus,in south-eastern,Australia

Mulloway (Argyrosomus japonicus) occur in estuarine and coastal waters surrounding Australia, Africa, India, Pakistan, China, Korea and Japan, where they are important in fisheries. This study identified that mulloway in south-eastern Australia had similar growth rates, but matured at smaller lengths and younger ages, to those in South Africa and Western Australia. Growth of both sexes was similar to about 5 years, after which females grew faster and attained a greater maximum length than males. Female mulloway matured at 4–5 years of age with a L₅₀ of 68 cm, whereas males matured at 2–3 years of age with a L₅₀ of 51 cm. The commercial fishery in New South Wales was characterised by declining catches and a reduction in the proportion of mulloway of mature lengths in landings. During 2002–2005 commercial landings were dominated (83%) by fish within 15 cm of the current minimum legal total length of 45 cm and aged 2 and 3 years (>80%), even though mulloway can attain lengths of 200 cm and live >30 years. Estimates of the rates of instantaneous total mortality ranged between 0.34 and 0.45, whilst the rate of instantaneous natural mortality (M) was estimated to be approximately 0.12. Yield-per-recruit analyses indicated that mulloway in New South Wales are being growth overfished and substantial increases in yield could be achieved by increasing the length at first harvest. Values of the spawning potential ratio were below 0.2 under a range of mortality estimates, suggesting that mulloway are at risk of recruitment overfishing. These results suggest that the spawning stock of mulloway in south-eastern Australia has been depleted and that remedial management action is required to protect this iconic species.     

Effects of Mosquitofish,Gambusia affinis,on Channel Catfish,Ictalurus puncatatus,Production Ponds

Mosquitofish, Gambusia sp., have been spread throughout the world to biologically control mosquitoes. However, the fish has gained a reputation as an invasive species and has been implicated in displacing native aquatic species. Gambusia affinis are native to the southeastern United States and commonly occur in commercial channel catfish, Ictalurus punctatus, production ponds. We investigated effects of mosquitofish presence on zooplankton populations, water quality, disease occurrence, and fish production in experimental ponds. There were no differences between ponds with or without mosquitofish in numbers of calanoid copepods, cyclopoid copepods, total copepods, Bosmina sp., Ceriodaphnia sp., Moina sp., Daphnia sp., or total cladocerans. There were also no differences in copepod and cladoceran sizes. Copepod nauplii were more numerous during the summer months in ponds with mosquitofish. There were no differences in water quality variables (soluble reactive phosphorus, nitrate, nitrite, ammonia, total nitrogen, total phosphorus, pH) or phytoplankton density between ponds stocked with and without mosquitofish. Catfish production and disease occurrence were also similar between ponds with and without mosquitofish. Although mosquitofish may cause problems when stocked outside their native range, there does not appear to be any adverse effects of mosquitofish presence in catfish production ponds.     

Surface disinfection of Pacific threadfin, Polydactylus sexfilis, and amberjack, Seriola rivoliana, eggs

The effects of exposing the eggs of Pacific threadfin and amberjack eggs (AEs) to different concentrations of hydrogen peroxide for 5 min on hatch rate and survival were assessed in a series of experiments using a petri dish model rearing system. Despite significant inter‐batch variation in hatch rate, it was shown that eggs of both species could be safely exposed to up to 11 340 mg L⁻¹ H₂O₂ for 5 min. Exposure to 34 230 mg L⁻¹ H₂O₂ for 5 min was shown to be lethal to AEs at a late stage of development. In two further experiments, it was demonstrated that Pacific threadfin eggs were resistant to all tested concentrations of a range of polyvinylpyrrolidone iodine (PVP‐I) concentrations and contact times (up to 1000 mg L⁻¹ PVP‐I for 10 min). The level of bacteria adhering to the eggs of both species was highly variable. Where eggs were heavily colonized (>10⁴ cfu egg⁻¹), hydrogen peroxide concentrations of at least 11 340 mg L⁻¹, or PVP‐I concentrations higher than 500 mg L⁻¹ for 10 min, were required for effective sterilization. In less colonized batches, rinsing in sterile seawater or exposure to lower (550 mg L⁻¹) concentrations of H₂O₂ was sufficient to result in high apparent levels of surface sterility (<1 cfu egg⁻¹).     

驼背鲈(Chromileptes altivelis)的胚胎发育及仔、稚、幼鱼形态观察

对驼背鲈(Chromileptes altivelis)的胚胎发育及仔、稚、幼鱼的形态特征进行了详细的观察与研究,描述了从受精卵到仔、稚、幼鱼各发育期的时间和形态特征变化。结果表明,在水温25-26℃、盐度30的海水中,受精卵历时27 h 25 min完成整个胚胎发育过程,经历从卵裂、囊胚、原肠、神经胚到肌节形成、各器官的逐渐形成、变化、完善等一系列的胚胎发育和变化过程;根据其卵黄囊消长情况、鳞片的覆盖状态、体色发生的不同变化以及第二背鳍和腹鳍的消长,将胚后发育分为仔、稚、幼鱼3个阶段。在水温22-26℃、盐度29-31、DO≥5 mg/L的条件下,2-3 d仔鱼卵黄囊消失,开口摄食;生长发育至31 d,仔鱼已变态进入稚鱼期;培育至57 d,稚鱼完成变态,成为幼鱼。第二背鳍棘和腹鳍棘的生长与收缩等石斑鱼类早期发育的共性生长特征及其体表特性体色变化特征为驼背鲈胚后发育过程中最明显的特征。     

Effect of Temperature on Growth,Energy Budget,and Physiological Performance of Green,White, and Purple Color Morphs of Sea Cucumber,Apostichopus japonicus

As an intertidal species, Apostichopus japonicus is subject to diel and seasonal temperature fluctuations. Color variation is a distinct characteristic of A. japonicus, and a new color morph, purple A. japonicus, was recently found on the coast of Rushan, Weihai City. This study was conducted to compare the performance of green, white, and purple color morphs of A. japonicus at different water temperatures to help improving aquaculture technology and management. In this study, green, white, and purple color morphs of juvenile A. japonicus (1.5 ± 0.1 g) were cultured at 10, 14, 18, 22, and 26 C for 60 d, according to the suitable temperature range for sea cucumber growth. Temperature was shown to have a significant effect on growth, energy budget, and physiology of sea cucumbers (P < 0.05). Specific growth rates, feed conversion efficiencies, and the proportion of energy allocated to growth of all three color morphs were optimal at 18 C. Activities of the enzymes related with oxidative stress, immune response, and digestion were determined. Superoxide dismutase (SOD) and trypsin activities generally reached a maximum in all three color morphs at 18 C. The purple color morph of A. japonicus was higher in growth rate, food conversion efficiency, and proportion of energy allocated to growth than green and white color morphs at 18 and 22 C, consistent with its higher trypsin and SOD activity, indicating the mutual effect of growth and physiology. At 18, 22, and 26 C, the green color morph had the highest level of lysozyme activity and purple color morph had the lowest, indicating possible infection by external pathogens of green color morph, which might be caused by high temperature. These results suggested that the optimum temperature for culture of the three color morphs was approximately 18 C, the purple had a better adaption to high temperature, and the green and white color morphs may be more susceptible to thermal stress than the purple color morph.     

Effect of temperature,volume of ova batches,and addition of a diluent,an antibiotic,oxygen and a protein inhibitor on short-term storage capacities of turbot,Psetta maxima,ova

The effect of different parameters on short-term storage capacity of turbot ova was assessed over a 45-h period after ova collection for fertilization rates and over a 9-h period after ova collection for hatching rates. Increasing the volume of ova sampling from 0.5 to 2.5 mL, as well as adding an antibiotic–antimicotic solution or oxygen did not significantly change the storage capacity of ova. Regarding the hatching rates, a higher storage ability was recorded at 8 and 13 °C, compared to 3 °C. The mean composition of the ovarian fluid was determined (n = 57 spawns). Use of a diluent mimicking the ovarian fluid significantly decreased the storage ability as assessed by the fertilization rates but did not modify the hatching rates. Diluting ova in an artificial ovarian fluid deprived of calcium significantly decreased the fertilization and hatching rates during the storage period. Furthermore, addition or not of soybean trypsin inhibitor (Sigma T 9003) to the artificial ovarian fluid deprived of calcium did not significantly change the results. Storage capacity of control batches of ova was low: at 13 °C, without any diluent and when ova were fertilized 3 h after stripping, the hatching rate was lowered to 62.4 ± 29.4 % (mean ± SD) of the initial value.     

Effects of Dietary Savory and Myrtle Essential Oils on Growth,Survival, Nutritional Indices,Serum Biochemistry,and Hematology of Farmed Rainbow Trout,Oncorhynchus mykiss,Fry

The effects of diets containing different levels of essential oils from savory Satureja khuzestanica Jamzad and myrtle Myrtus communis L and an immunity complement were investigated on growth, survival, nutritional indices, serum biochemistry, and hematology of farmed rainbow trout, Oncorhynchus mykiss, fry (n = 4500; 5 ± 2 g). The essential oils were dosed as 300 and 500 mg/kg diet. After 60 d, the fish fed 300 mg/kg of the essential oils showed the highest counts of white blood cells (P < 0.05). The same treatment revealed the greatest levels of hematocrit, total protein, and albumin, but glucose and cholesterol values significantly decreased compared with the control (P < 0.05). Feeding fish with 300 mg/kg of the essential oils led to highest records of specific growth rate and survival rate but the lowest feed conversion ratio (FCR), and those fed with immunity complement attained the lowest values of growth parameters. The fry fed with immunity complement and 300 mg/kg of myrtle essential oil achieved the highest and lowest FCR values, respectively. The results indicate that dietary supplementation of 300 mg/kg of the above essential oils exert positive impacts on the growth performance, feeding efficiency, and hematological factors in O. mykiss.     

Sperm Motilities in Waigieu Seaperch,Psammoperca waigiensis: Effects of Various Dilutions,pH, Temperature,Osmolality, and Cations

The objectives of this study were to evaluate the effects of varying dilutions, pH, temperature, osmolality, and cations on sperm motility parameters in waigieu seaperch, Psammoperca waigiensis. The maximum velocity of average in path (VAP), percentage of motile cells (MOT), and duration of sperm motility (DSM) were observed when semen was diluted in artificial seawater (ASW) at a ratio of 1:100 (144.9 ± 0.6 µm/sec, 95.6 ± 0.4%, and 230.3 ± 2.3 sec, respectively), at 30 C (142.0 ± 0.6 µm/sec, 93.6 ± 0.4%, and 238.3 ± 0.9 sec, respectively), and pH 8 (144.8 ± 0.6 µm/sec, 93.3 ± 0.4%, and 234.0 ± 1.5 sec, respectively). Maximum VAP, MOT, and DSM were obtained in each solution containing 0.6 M NaCl (143.8 ± 1.0 µm/sec, 91.3 ± 2.0%, and 230.6 ± 4.2 sec, respectively), 0.6 M KCl (135.1 ± 3.1 µm/sec, 91.1 ± 3.1%, and 230.3 ± 3.7sec, respectively), 0.2M CaCl₂ (105.3 ± 4.7μm/sec, 47.9 ± 2.7%, and 120.7 ± 1.3 sec, respectively), 0.2 M MgCl₂ (107.3 ± 3.0 m/s, 42.1 ± 3.3%, and 120.3 ± 4.8 sec, respectively), and osmolality of 400 mOsm/kg (145.1 ± 2.5 µm/sec, 93.0 ± 2.1%, and 346.5 ± 4.4s, respectively). We used these mediums as artificial insemination media for fertilizing matured eggs. The results showed that the fertilization and hatching rates in 0.6 M NaCl (75.3 ± 0.6% and 57.0 ± 2.4%, respectively), ASW (70.8 ± 1.2% and 51.2 ± 1.8%, respectively), or 400 mOsm/kg (72.9 ± 1.8% and 55.3 ± 1.6%, respectively) were higher than that in seawater (63.9 ± 1.2% and 39.2 ± 3.9%, respectively). In conclusion, using 0.6 M NaCl, ASW, or 400 mOsm/kg as an artificial insemination medium is effective for fertilizing of waigieu seaperch.