好氧反硝化菌对水质和鱼体饲喂效果的影响研究

以好氧反硝化菌株Bacillus sp.H2作为供试菌株,从水质指标、鱼体生长指标和免疫指标3方面全面考察菌株Bacillussp.H2作为水质改良剂对养殖水体和鱼体饲喂效果的影响。研究表明,菌株Bacillus sp.H2对水体亚硝态氮的平均降解率达到64.04%,总氮最终降解率达到16.0%,COD的最终降解率达到...     

芽孢杆菌对草鱼生长和肠粘膜抗氧化功能及养殖水质的影响

本试验研究了饲料中添加芽孢杆菌对草鱼生长、肠粘膜抗氧化功能及养殖水体水质的影响。选取平均体重为（51.0±2.3）g的健康草鱼300尾，随机分成3组（对照组、处理组1和处理组2），每组3个重复，每个重复50尾鱼。其中对照组饲喂基础日粮，处理组1和2分别饲喂含复合芽孢杆菌（105 cfu/克饲料，枯草芽孢杆菌和解淀粉芽孢杆菌以1:1比例混合）和枯草芽孢杆菌（105 cfu/克饲料）的基础日粮。试验期为45d。结果表明，饲料中添加芽孢杆菌对养殖水体pH和硝酸盐氮含量无显著影响，但显著降低了从第21d到试验结束期间水体中亚硝酸盐氮的含量（处理组1第35d除外）。芽孢杆菌的添加同时显著降低草鱼的死亡率（P<0.05），并提高了草鱼的增重率和特定生长率。与对照组相比，处理组1和2草鱼的增重率分别提高了52.93%（P<0.01）和21.78%（P<0.05），特定生长率分别提高了44.44%（P<0.01）和16.67%（P<0.05）；而且处理组1草鱼增重率和特定生长率分别比处理组2提高了25.58%（P<0.01）和23.81%（P<0.01）。肠粘膜抗氧化活性研究表明，与对照组相比，饲料中添加芽孢杆菌能提高草鱼肠粘膜超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性。以上结果提示，饲料中添加芽孢杆菌可以改善养殖水质和草鱼肠粘膜抗氧化功能，并显著促进草鱼生长并降低死亡率。     

蛹肽蛋白替代鱼粉对大菱鲆(Scophthalmus maximus L.)幼鱼生长、饲料利用、消化代谢酶及免疫性能的影响

选取蛹肽蛋白分别替代大菱鲆幼鱼配合饲料中0、15%、30%、45%、60%、75%的鱼粉,配制成6种等氮等能的饲料饲喂大菱鲆幼鱼(19.84±0.04 g)56 d,以研究蛹肽蛋白替代鱼粉的效果。结果显示,大菱鲆幼鱼的特定生长率、饲料效率随替代水平的升高而降低,30%及以上替代组显著低于对照组(P<0.05);鱼体粗蛋白、粗脂肪水平随替代水平的升高而降低,分别在75%和30%及以上替代组显著降低,鱼体水分和灰分含量随替代的升高而升高,分别在75%和30%及以上替代组显著升高(P<0.05)。摄食率随替代水平升高呈先上升后下降的趋势,在30%替代组呈现出最高的摄食率,且显著高于对照组(P<0.05)。饲料干物质的表观消化率在42.53%-54.36%之间,且当替代水平达到75%时显著低于对照组(P<0.05);而蛋白质表观消化率在71.67%-86.89%之间,仅45%和75%替代组显著低于对照组(P<0.05)。各替代组肝脏超氧化物歧化酶活性均高于对照组,在45%和60%替代组出现显著性差异(P<0.05)。综上所述,蛹肽蛋白可以替代大菱鲆幼鱼饲料中15%的鱼粉而不影响其生长摄食、饲料利用以及与消化、代谢、免疫相关的酶的活性。     

史氏鲟幼鲟对饲料中磷的需要量

通过生长饲养试验研究史氏鲟幼鲟对饲料中磷的需要量.以Ca(H2PO4)2·H2O为磷源,配制含磷水平分别为0.18%(对照组),0.40%,0.71%,0.98%,1.38%和1.66%的6组等能等氮纯化饲料,每组饲料饲喂3个重复,每个重复饲养20尾初体质量约为4.7 g的幼鲟.经过8周的饲养后,对生长、饲料效率、成活率、幼鲟肌肉常规组成及脊椎骨灰分和钙磷含量进行分析.结果表明,随饲料中磷含量的升高,鱼体增重率、饲料效率和特定生长率显著增加(P<0.05),直至0.98%组达最大,然后随着饲料磷含量的增加,这些指标显著降低(P<0.05);试验各添加组的成活率显著高于对照组(P<0.05),但各添加组间没有显著差异(P>0.05);饲料添加磷对鱼体肌肉水分、粗蛋白质和粗脂肪含量无显著影响(P>0.05);当饲料磷含量在0.71%～1.66%之间时,脊椎骨中灰分、钙和磷含量差异不显著(P>0.05),但显著高于对照组和0.40%试验组(P<0.05).经过折线回归分析得出,为维持史氏鲟幼鲟最佳生长和骨骼磷水平,饲料中磷的需要量为0.88%～1.00%(占干饲料).     

膨化与非膨化饲料对大规格草鱼生长、体成分及部分生理生化指标影响

以商业配方为基础，配制膨化饲料和非膨化饲料饲喂初始体重（394.96±13.21g）草鱼（Ctenopharynodon idellus）120天，旨在对比这两种饲料对其生长、体成分及部分生理生化指标的影响。养殖试验在水库网箱（2m×2m×2m）中进行，每个处理组3个重复，每个重复30尾鱼。实验结果表明，与非膨化料组相比，膨化饲料组草鱼成活率和增重率显著提高（P＜0.05），饵料系数显著降低（P＜0.05），增重成本显著降低（P＜0.05）；肥满度、肝体比、脏体比和肠体比显著升高（P＜0.05）；鱼体血清血糖、甘油三酯、总固醇和过氧化氢酶显著升高（P＜0.05）；胰蛋白酶、淀粉酶和脂肪酶显著降低（P＜0.05）；肝脏谷丙转氨酶（GPT）显著升高，谷草转氨酶（GOT）显著降低（P＜0.05）；鱼体成分中水分和灰分无显著差异（P>0.05），粗脂肪显著升高、粗蛋白显著降低（P＜0.05）。综上所述，与非膨化饲料相比，饲喂膨化饲料可使大规格草鱼生长性能和养殖效益提高，但会鱼体肥满度和粗脂肪含量提高。     

江蓠、浒苔、藻渣和菌渣替代鱼粉对红鳍东方鲀幼鱼生长性能、相关生化指标的影响

本实验旨在研究江蓠(Gracilaria verrucosa)、浒苔(Enteromorpha prolifera)、藻渣和菌渣替代鱼粉对红鳍东方鲀(Takifugu rubripes)幼鱼生长性能、血清和肝脏生化指标和体组成的影响。实验共制成6种等氮、等脂的饲料，以含鱼粉60%为对照组1和45%鱼粉的为对照组2，分别将10%的江蓠、浒苔、藻渣、菌渣与植物蛋白质配合后替代对照组1饲料中30%的鱼粉，投喂初始体重为(17.33±0.55) g的红鳍东方鲀幼鱼56 d。结果显示，1)浒苔组特定生长率(SGR)显著高于其他5组(P<0.05)，藻渣组SGR显著高于对照组2和江蓠组(P<0.05)，与对照组1和菌渣组无显著差异(P>0.05)；对照组1和浒苔组饲料效率(FER)显著高于对照组2和菌渣(P<0.05)，与江蓠和藻渣组无显著差异(P>0.05)；对照组1的蛋白质沉积率(PPV)和蛋白质效率(PER)显著高于对照组2和菌渣组(P<0.05)，与江蓠、浒苔和藻渣组无显著差异(P>0.05)。2)各组血清和肝脏中谷丙转氨酶(GPT)和谷草转氨酶(GOT)活性均无显著差异(P>0.05)。各组血清丙二醛(MDA)含量和超氧化物歧化酶(SOD)活性均无显著差异(P>0.05)。3)菌渣组鱼体粗蛋白质含量显著高于藻渣组(P<0.05)，与对照组1、对照组2、江蓠和浒苔无显著差异(P>0.05)；浒苔和藻渣组鱼体粗脂肪含量显著高于对照组2 (P<0.05)，与对照组1、江蓠和菌渣组无显著差异(P>0.05)。综合来看，将10%江蓠、浒苔、藻渣和菌渣与植物蛋白质配合后替代饲料中30%的鱼粉对红鳍东方鲀幼鱼的生长性能无不良影响，并且浒苔可以显著提高红鳍东方鲀的生长性能。     

核糖蛋白替代鱼粉对大菱鲆幼鱼生长性能、肠道消化酶活性、免疫能力及血清生化指标影响

本研究旨在评价核糖蛋白替代大菱鲆(Scophthalmus maximus)饲料中鱼粉的潜力。采用单因素实验设计,设6个鱼粉替代水平。对照饲料(D1)中鱼粉含量为45%,通过添加核糖蛋白替代D1组饲料中鱼粉的0.5%(D2)、1%(D3)、2%(D4)、3%(D5)和4%(D6)。实验期间,每天分2次按饱食量投喂初始体重为(24.00±0.30)g大菱鲆幼鱼56 d。结果显示,幼鱼增重率、特定生长率、蛋白质效率随着核糖蛋白替代水平的变化呈先上升后下降趋势,均在D3组达到最高值,显著高于D5和D6组(P<0.05);饲料系数则呈相反趋势,在D3组达到最低值,显著低于D6组(P<0.05)。各替代组幼鱼血清胰岛素生长因子(IGF-1)和生长激素(GH)含量均显著低于对照组(P<0.05);核糖蛋白替代1%~3%的鱼粉后,显著提高了幼鱼肠道胰蛋白酶活性(P<0.05);幼鱼肠道α-淀粉酶活性在D4和D5组显著高于对照组(P<0.05);饲料中添加核糖蛋白替代鱼粉显著降低了幼鱼肠道脂肪酶活性(P<0.05)。各替代组幼鱼血清总蛋白、球蛋白含量和碱性磷酸酶活性均显著高于对照组(P<0.05);D3组溶菌酶活性显著高于D6组(P<0.05);各组间幼鱼血清白蛋白含量和超氧化物歧化酶活性无显著差异(P>0.05),但各替代组均显著提高了幼鱼血清白介素β1(IL-1β)和肿瘤坏死因子(TNF-α)含量(P<0.05);与对照组相比,D4~D6组血清总胆固醇和甘油三酯含量显著降低(P<0.05),低密度脂蛋白在D5和D6组显著降低(P<0.05);高密度脂蛋白在D4组显著升高(P<0.05)。血糖浓度呈先升高后降低的趋势,D3组显著高于对照组(P<0.05)。攻毒实验结果显示,D2组大菱鲆幼鱼48 h累积死亡率最低为56.45%。研究表明,饲料中添加核糖蛋白替代1%鱼粉时,大菱鲆幼鱼生长、消化酶活力及鱼体的免疫能力和抗细菌感染能力均达到最高。     

饲料蛋白水平对星斑川鲽幼鱼生长、体组成及血浆生化指标的影响

以鱼粉为蛋白源,配制5个不同蛋白质水平(34.85%,40.48%,46.54%,51.54%,56.69%)的等能饲料.以初始体质量为(54.52±0.23)g的星斑川鲽(Platichthys stellatus)为实验对象,在室内循环水养殖系统中进行54 d的摄食生长实验,研究饲料蛋白水平对星斑川鲽幼鱼生长、体组成及血浆生化指标的影响.结果显示:(1)增重率(WGR)和特定生长率(SGR)随着饲料蛋白水平的增加而上升,51.54%和56.69%饲料组之间差异不显著(P>0.05),其余各组差异显著(P<0.05);51.54%饲料组的蛋白质效率(PER)显著高于其他各组(P<0.05);51.54%饲料组的蛋白质沉积率(PRE)也显著高于34.85%、46.54%和56.69%组(P<0.05),但与40.48%饲料组差异不显著(P>0.05).以增重率为参考指标,折线回归分析结果表明,星斑川鲽幼鱼获得最佳增重时对饲料中蛋白质的需要量为53.56%.(2)饲料不同蛋白水平对星斑川鲽幼鱼鱼体灰分含量没有显著影响,但显著影响了鱼体粗蛋白、粗脂肪和水分的含量(P<0.05).51.54%饲料组鱼体粗蛋白含量最高,显著高于34.85%组(P<0.05),而与40.48%、46.54%和56.69%组之间无显著差异(P>0.05);鱼体粗脂肪含量随着饲料蛋白水平的升高而下降,水分含量表现出与粗脂肪含量相反的趋势.(3)饲料蛋白含量对星斑川鲽幼鱼部分血浆生化指标也产生了显著性的影响.血浆总蛋白(TP)以51.54%组最高,与56.69%组差异不显著(P>0.05),,但显著高于34.85%、40.48%和46.54%组(P<0.05);40.48%、51.54%和56.69%组间血浆尿素氮(BUN)含量差异不显著(P>0.05),但显著低于34.85%和46.54%组(P<0.05).综合以上结果,星斑川鲽饲料中蛋白质适宜添加量为51.54%～53.56%.     

膨化沉性饲料和粉状饲料对菊黄东方鲀生长和氮磷收支的影响

为进一步探究膨化沉性饲料在菊黄东方鲀(Takifugu flavidus)养殖中的合理应用,在盐度7~10、水温22.6~29.4℃条件下,于室内水泥池开展了为期62 d的膨化沉性饲料与粉状饲料饲喂菊黄东方鲀的对比试验,比较2种饲料对鱼体生长和养殖系统氮(N)、磷(P)收支的影响。结果表明:(1)2个饲料组鱼的终末体质量、增重率、特定生长率、净产量、成活率、比肠长、肥满度等指标均无显著差异(P0.05);膨化沉性饲料组鱼的肝体比、脏体比显著高于粉状饲料组(P0.05),饲料系数显著低于粉状饲料组(P0.05)。(2)饲料是养殖系统中N、P的主要输入源,分别占总输入的67.7%~72.9%和76.4%~82.6%,其次为水体和养殖生物;养殖试验中膨化沉性饲料组投入的N、P量(51.46、9.64 g/m~2)显著低于粉状饲料组(65.97、14.18 g/m~2)(P0.05)。(3)废水(换水+终末水体)为N、P的主要输出源,分别占输入总量的61.7%~62.8%和45.2%~51.7%,其次为鱼体固定和吸污输出;膨化沉性饲料组经废水输出的P(5.71 g/m~2)和经吸污输出的N、P量(4.18、3.48 g/m~2)均低于粉状饲料组(8.88、6.11、4.50 g/m~2)(P0.05);被鱼体固定的N、P量组间差异不显著(P0.05)。(4)膨化沉性饲料组N、P的利用率分别为18.0%和16.5%,较粉状饲料组分别高42.9%和139.1%;水体N、P负荷量分别为70.55、15.35 kg/t,较粉状饲料组分别低32.9%和44.1%。研究表明,采用膨化沉性饲料饲喂菊黄东方鲀能提高饲料中N、P的利用效率,降低养殖系统的N、P排放。     

脂肪酶对南方鲇生长性能、消化酶活性及血液生化指标的影响

在基础饲料中分别添加0、0.1、0.3 g/kg的脂肪酶,饲喂平均体重(57.6±0.02)g的南方鲇(Silurus meridionalis Chen)60 d,测定南方鲇的生长性能、饲料表观消化率、消化酶活性及血液生化指标。结果显示:添加0.1 g/kg和0.3 g/kg的脂肪酶,增重率比对照组分别提高了4.0%和5.8%,但差异不显著(P>0.05),饲料系数分别下降了5.0%和6.6%,差异显著(P<0.05),肥满度和粗脂肪消化率显著提高(P<0.05),对内脏指数、肝脏指数、肠脂指数、胰蛋白酶活力、肠蛋白酶活力、肠脂肪酶活力及血液生化指标均没有显著影响(P>0.05)。添加0.3 g/kg的脂肪酶显著提高胰脂肪酶活力(P<0.05),添加0.1 g/kg的脂肪酶对胰脂肪酶活力没有显著影响(P>0.05)。结果表明,在脂肪水平为10%的饲料中添加0.3 g/kg的脂肪酶可以提高胰脂肪酶活力,提高脂肪消化率,改善饲料利用率。     

添加植酸酶日粮不同磷水平和钙磷比对生长肥育猪血液生化指标和骨骼性能的影响

本试验利用饲养试验方法,研究玉米-豆粕型日粮中添加植酸酶时不同磷水平和钙磷比对生长肥育猪血清指标和骨骼性能的影响。试验选用162头20kg左右的杜长大三元杂交猪进行2×3(磷水平×钙磷比)因子饲养试验,试验分2个阶段进行,前期为生长期体重在20-60kg,后期为肥育期体重为为60-100kg。结果表明:添加植酸酶日粮磷水平对血清磷含量和碱性磷酸酶的活性影响显著(P<0.05);钙磷比对血清钙和血清磷含量的影响显著(P<0.05);添加植酸酶日粮磷水平和钙磷比对生长肥育猪骨骼性能的影响不显著(P>0.05)。在添加植酸酶条件下,降低日粮磷水平不影响猪的正常生长发育。     

RESOURCE USE EFFICIENCY AND SOCIAL PROFITABILITY OF AN INTEGRATED AQUA-FARM,TRIPURA, INDIA

The nature of resources available and how they are combined and utilized in aquaculture largely determine its economic viability and social profitability. Using a novel Resource Cost Ratio (RCR), this study analyzes resource use efficiency and social profitability of an integrated aqua farm located in Tripura, India. RCR, a variant of the Domestic Resource Cost Ratio (DRCR), is the ratio of the net cost of non-marketable resources and the net value addition by using marketable resources. The RCR for the integrated farm was found to be ?0.24. The negative value of RCR shows positive profitability for the integrated farm. The corresponding value for a specialized farm was found to be 0.52. The difference is the greater resource use efficiency of the integrated approach. Private and social profits per unit cost for the integrated farm (0.26 and 0.08, respectively) were higher than for the specialized farm (0.11 and 0.04, respectively).     

泥蚶促熟技术

将泥蚶放在对虾池中蓄养，其性成熟比放养在自然海区的提前3个月，此法提早并延长了泥蚶的繁殖期，是提高泥蚶苗种产量和经济效益的重要手段之一。     

饥饿胁迫对刺参(Apostichopus japonicus)免疫和生长的影响

为了探究饥饿胁迫对刺参免疫和生长的影响，在11?13℃条件下，研究体质量为(20±0.15) g的刺参在不同时间(0、10、20、30、40、50、60 d)，饥饿胁迫对体腔液中酸性磷酸酶(ACP)活性、溶菌酶(LZM)活性、超氧化物歧化酶(SOD)活性、呼吸爆发(RB)活性、吞噬活性以及对刺参体质量、脏壁比、存活率的影响。研究结果表明，随着饥饿时间的延长，刺参体腔液中的ACP活性、LZM活性呈现降低的趋势，饥饿60 d后，比初始值分别下降47.06%、17.57%；SOD活性、RB活性和吞噬活性呈现出先上升后下降的趋势，分别在饥饿胁迫第20、20、10天时达到最高值依次为32.88、0.328、1.35 U/ml，其后显著下降，第60天时显著低于初始值，分别下降27.87%、38.08%、53.43%；其体质量在第60天时为初始体质量的68.08%，呈现负生长；脏壁比逐渐增大，第60天时为0.56，显著高于初始值0.44 (P<0.05)。随着存储营养物质的消耗，刺参体质量损失率增加，存活率下降，存活率与体质量损失率之间存在着y = ?0.0354x2+0.4354x 99.117的函数关系，呈二次曲线线性负相关。研究结果显示，饥饿时刺参通过消耗体内的营养物质来满足机体需要，长期的饥饿有可能降低刺参的免疫能力，直接影响刺参的健康和生长。     

Feeding management and waste production in semi-intensive farming of penaeus monodon (fab.) at different stocking densities

Studies on waste production and feeding management of Penaeusmonodon in semi-intensive culture system were carried out for foursuccessive crops at a commercial farm (M/S Suryo Udyog Ltd.) at Chandipur Coastof Orissa, India, at six different stocking densities. The prescribed feedingprogramme of C.P. Group, Thailand (NOVO-shrimp feed) were adopted andstandardized during first two crops and the standardized feeding scheme wasevaluated in the last two crops. Influence of standardized feeding programme onaverage feed conversion ratio (FCR) of P. monodon washighlysignificant (p < 0.001) against that of manufacturer's (NOVO-feed)prescribedfeeding programme. A feeding frequency of more than four times a day showed noimprovement in growth rate and there was no change in diurnal feeding habitprobably due to the fact that, in scientific farming, aquatic environment isartificially controlled. It was also observed that, as the age and weight ofshrimp increases, feed % decreases from 8.8 to 1.9% and lift net(LN)% increases from 2.4 to 4.3% for 1–40 gmeanbody weight of P. monodon respectively. The higher thestockingdensity, the higher was the FCR and sedimentation rate. In the presentexperiment,the sedimentation rate was estimated to be 49.5 m³ (dryvolume)/1000.0 kg of shrimp biomass. The average quantity of wastematter production was only 571.4 kg of organic matter, 10.21kg of nitrogen and 0.527 kg of phosphorus at anaverage FCR of 1.437 and stocking density of 22.5 pcs m^-2 during the four crop experimental period.     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO₂ and ions should be more often evaluated. Plasma Na⁺ and Cl^‐ are very useful markers of acidosis, due to their respective exchange for H⁺ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters.