施氏鲟幼鱼摄食和生长的最适水温

实验用施氏鲟(AcipenserschrenckiiBrandt)幼鱼为黑龙江捕获的野生亲本经人工繁殖、培育所得,8月龄,体长(32 63±1 80)cm,实验周期35d。实验设计了4个水温处理组,实验水温分别为17℃、20℃、23℃和26℃,实验观察到,生活在不同水温环境中的幼鱼表现出不同的生长特性,养殖在23℃温度环境中的施氏鲟幼鱼的生长速度显著高于其他处理组幼鱼,水温对施氏鲟的特定生长率(SGR)、日增重(DWG)、食物转化率(FCR)和摄食率(FR)有着显著的影响。这些参数与水温(T)之间的相关关系可用二次回归曲线来描述,生长率与水温的回归方程式为:SGR=-12 933+1 418T+(-0 033)T2,摄食率与水温的关系式为:FR=-5 324+0 719T+(-0 016)T2。根据回归方程,求得施氏鲟幼鱼的最适生长水温为21 53℃,最大摄食率的水温为22 33℃。结论认为,施氏鲟在水温17～26℃都可摄食生长,但在20℃时最适宜;同时证实,施氏鲟最适生长温度要低于其最适摄食温度。     

The effects of feeding frequency on growth of juvenile Atlantic halibut, Hippoglossus hippoglossus L.

Four experiments were conducted to investigate the effects of feeding frequency on growth of juvenile Atlantic halibut, Hippoglossus hippoglossus L. Fish (22–75 g) fed three (3 ×) or five times per day (5 × day^?1) under constant light and temperature (13±1°C) consumed significantly more feed than fish fed 1 × day^?1 but by the end of the experiment only fish fed 5 × day^?1 were heavier and had greater specific growth rates (SGR). Under simulated winter conditions (9L:15D, 5±1°C), halibut (～300 g) fed every other day consumed more feed, had a greater SGR and final weight compared with fish fed every third day. Feed conversion ratios were not different among treatment groups in any of the experiments. These results suggest that growth rates may be improved by feeding juvenile halibut more than 1 × day^?1.     

不同盐度驯化模式对施氏鲟生长及摄食的影响

采用逐步增盐法（IG）、阶段增盐法（IT）及盐度突变法（is）3种不同的驯化模式对施氏鲟（Acipenser schrenckii）进行盐度驯化，对3种模式下的特定生长率（SGR）、生长效率（GE）、摄食率（FR）及食物转化率（FCR）进行统计，并与对照组（CT）进行比较分析。结果表明，驯化方法对于施氏鲟的成活率具有较大影响，3种不同驯化模式下的成活率由高到低依次是IT（100％）、IS（93．33％）、IG（85％），各盐度驯化组死亡个体规格均较小。盐度对于施氏鲟的生长具有一定的抑制作用，盐度驯化各组在SGR、GE方面均低于对照组，IS组和IG组SGR与CT组无显著性差异（P〉0．05），IT组显著（P〉0．05）低于CT组。IG、IS、IT组与CT组相比，摄食率有所下降，但无显著差异（P〉0．05）。IG、IT、IS各组FCR均低于对照组，但对照组FCR与IG、IS组没有显著差异，与IT组差异显著（P〈0．05）。结论认为，尽管盐度对于施氏鲟的生长具有一定的影响，但是通过IG及IS方法的驯化，施氏鲟在25盐度下仍然保持一定的生长速度。     

蛋氨酸硒含量对食用仿刺参生长和体壁营养成分的影响

在水温10.2~12.4℃、p H 7.8~8.0、盐度24~28条件下,将平均体质量为(45±5)g的仿刺参Apostichopus japonicus饲养在室内养殖池的网箱中,投喂蛋氨酸硒添加量分别为0mg/kg、0.2mg/kg、0.4mg/kg、0.6mg/kg、0.8mg/kg和1.0mg/kg的6组饲料。饲养60d后,测定仿刺参的特定生长率(SGR)和体壁中常规营养成分含量。结果表明:当蛋氨酸硒添加量为1.0mg/kg饲料时,仿刺参的特定生长率、粗蛋白、粗灰分含量最大,较对照组分别高155.56%、5.65%和2.9%(P0.05),而仿粗脂肪含量最低,较对照组低10.61%(P0.05)。     

CO_2浓度对细基江蓠繁枝变型生长和光合特性的影响

比较了低CO_2浓度(充无CO_2空气,low CO_2,简称LC)、正常CO_2浓度(充正常空气,normal CO_2,简称NC)、高CO_2浓度(充正常空气+0.2%CO_2,high CO_2,简称HC)3种条件下细基江蓠繁枝变型(Gracilaria tenuistipitata var.liui Zhang et Xia)的特定生长率、光合色素含量、光合放氧速率和叶绿素荧光参数。结果表明:培养6 d后,与NC组相比,LC组细基江蓠繁枝变型特定生长率(SGR)、100μmol·(m~2·s)~(-1)光强净光合放氧速率及PSII最大光量子产率(Fv/Fm)均显著降低(P0.05);类胡萝卜素含量显著增加(P0.05);而藻红素、叶绿素a含量、PSII实际光量子产率(Fv/Fo)、快速光响应曲线初始斜率(α)、最大电子传递效率(ETR_(max))及半饱和光强(I_k)均无显著差异(P0.05)。与NC组相比,HC组细基江蓠繁枝变型的SGR、Fv/Fm及α显著增加(P0.05),藻红素含量显著下降(P0.05),而叶绿素a、类胡萝卜素含量、600μmol·(m~2·s)~(-1)光强净光合放氧速率、Fv/Fo、α、ETR_(max)及I_k均无显著差异(P0.05)。与LC组相比,HC组细基江蓠繁枝变型的100μmol·(m~2·s)~(-1)光强净光合放氧速率、SGR、Fv/Fm、Fv/Fo、α均显著增加(P0.05),而藻红素、叶绿素a、类胡萝卜素含量却显著下降(P0.05),600μmol·(m~2·s)~(-1)光强净光合放氧速率、ETR_(max)、I_k无显著变化(P0.05)。对于细基江蓠繁枝变型,CO_2浓度升高降低了光合色素含量,同时提高了光系统光能转换效率,而对藻体饱和光强下净光合放氧速率的促进作用不显著。但是CO_2浓度升高却仍然可能通过降低无机碳利用的能量消耗及提高营养盐吸收利用而显著促进藻体的生长。比较不同CO_2浓度下细基江蓠繁枝变型生长和光合特性的差异,有助于初步揭示其对大气CO_2浓度变化的响应特征。     

养殖密度对饲料驯化期西伯利亚鲟生长的影响

研究了养殖密度对饲料驯化期西伯利亚鲟(Acipenser baerii)稚鱼生长和存活的影响。试验设置5个养殖密度(1.843、1.638、1.433、1.228、1.024 kg/m3)。试验期间采用依次投喂水蚯蚓、软颗粒饲料、硬颗粒饲料的驯养方法,逐步从活饵料转喂人工配合颗粒饲料。试验结果表明,最大密度组D1溶解氧达到最低值4.09 mg/L,接近鲟鱼正常生长发育的临界溶氧;高密度组D1、D2、D3和低密度组D4、D5死亡率和终体重差异显著(P<0.05);D3特定生长率(SGR)均值最大,D1、D2和D3、D4、D5的SGR差异显著(P<0.05);D4的终体重、日增重(DWG)、肥满度(CF)最大,各密度组对DWG、CF和体长及体重变异系数(CV)的影响较小(P>0.05)。试验期间从D1到D5组的死亡率依次为2.06%,1.99%,1.87%,1.68%和1.64%,CF为0.498～0.532,SGR平均值为11.16%～13.14%,体重CV为30.72%～33.54%,体长的CV为6.64%～9.94%。根据试验结果,建议饲料驯化期西伯利亚鲟稚鱼的适宜养殖密度控制在1.228～1.433 kg/m3,即直径2 m的玻璃缸每缸3 000～3 500尾。     

温度和盐度对墨吉明对虾(Fenneropenaeus meiguiensis)生长与存活的联合效应

采用中心复合设计(CCD)和响应曲面法(RSM),研究了温度(16–35℃)和盐度(5–29)对墨吉明对虾生长与存活的联合效应。结果显示,温度的一次效应和二次效应对墨吉明对虾的特定生长率和存活率具有显著影响(P<0.05);盐度的一次效应对墨吉明对虾的特定生长影响不显著(P>0.05),但对墨吉明对虾存活率的影响达到显著水平(P<0.05);盐度二次效应对特定生长率与存活率具有极显著影响(P<0.01);温度和盐度对墨吉明对虾的生长与存活不存在显著的交互作用(P>0.05)。采用中心复合设计建立了温度和盐度对墨吉明对虾特定生长率和存活率影响的模型方程,该方程的决定系数分别为0.9014、0.9631,校正系数分别为0.8310、0.9367,表明模型具有较好的拟合度,可用于预测墨吉明对虾特定生长率与存活率的变化。通过模型优化和验证实验,得出温度为26.6℃、盐度为15.5时,特定生长率和存活率均达到最大值,分别为1.296%,98.34%,其满意度为0.970。结果显示,墨吉明对虾在工厂化养殖过程中温度为26–27℃、盐度为15–16时,有利于墨吉明对虾的存活与生长。     

贝壳上污损生物的重量对栉孔扇贝生长和存活的影响

对网笼养殖的栉孔扇贝壳上污损生物的数量进行了研究,发现9～11月贝壳上污损生物的湿重分别为1．47、0．49和2．09g,与上壳重的比值分别为28．16％、10．24％和31．29％。通过在栉孔扇贝上壳添加上壳干重0．5、1、2和3倍重的水泥,用以模拟附着在扇贝壳上的污损生物,设不添加水泥的对照组,对贝壳上污损生物的重量对栉孔扇贝生长和存活的影响进行了研究。结果表明,实验组扇贝壳长、闭壳肌和剩余软体组织的特定增长率及存活率与对照组均没有显著差异（P〉0．05）,说明贝壳上的污损生物的重量没有影响扇贝的生长和存活。     

Performance of different types of diets on experimental larval rearing of endangered Chitala chitala (Hamilton) in recirculatory system

This is the first report on the successful larval rearing of captive bred population of Chitala chitala (Hamilton). C. chitala is one of the endangered fresh water fish species in India for which the development of controlled larval rearing procedures are needed for stock enhancement. Fifteen days old post-hatchlings were stocked for 28 d in a 30 L recirculatory tanks using eight different diets i.e. live feed (tubifex worms, chironomous larvae, zooplanktons,), dry feed (dry tubifex, spirulina, daphnia) and other non-conventional feed (fish eggs and boiled egg-yolk). Fishes accepted all types of diets. The study revealed that specific growth rate (SGR) was higher in post-hatchlings fed on live tubifex worms (2.40 ± 0.72) followed by fish eggs (2.15 ± 0.71), dry tubifex (2.12 ± 0.40), chironomous larvae (1.91 ± 0.44), spirulina (1.79 ± 0.38), daphnia (1.42 ± 0.79) and planktons (1.37 ± 0.77) whereas minimum SGR was recorded with boiled egg-yolk (0.63 ± 0.5). A highly significant difference (p < 0.01) in SGR was observed in fish fed on live feed (tubifex worms, chironomous larvae, planktons, spirulina), dry tubifex and fish eggs whereas for daphnia and boiled egg-yolk it was only significant (p < 0.05). The final mean weight and weight gain showed highly significant difference (p < 0.01) in live tubifex, zooplanktons, spirulina, chironomous larvae, dry tubifex and fish eggs, whereas daphnia and boiled egg-yolk fed larvae showed significant difference (p < 0.05). Highest mean survival rate on day 28 was observed in live tubifex worms (94%) and chironomous larvae (92%). The post-hatchlings reared with spirulina and daphnia showed same survival rate of 88% whereas the lowest mean survival of 66% was recorded in boiled egg-yolk. The experiments showed that captive bred post-hatchlings of C.chitala could be reared in experimental recirculatory system for attaining higher growth and survival during early life stages. However, methods to improve the larval rearing have to be improved further for commercial farming of the species.     

Effects of dietary pyridoxine on growth and biochemical responses of Labeo rohita fingerlings exposed to endosulfan

A sixty-day experiment was carried out to study the effect of dietary pyridoxine (PN) on growth performance, RNA/DNA ratio and some biochemical parameters of Labeo rohita fingerlings exposed to sub-lethal dose of endosulfan (1/10th of 96 h static non-renewal LC₅₀ = 0.2 ppb) to assess the role of pyridoxine in ameliorating the negative effects of endosulfan. Two hundred seventy fingerlings (6.5 ± 0.26 g) were randomly distributed into six treatments in triplicates (15 fish/tank). Five iso-nitrogenous (35.45-35.75% crude protein) purified diets were prepared with graded levels of pyridoxine. Six treatment groups were T₀ (10 mg PN + without endosulfan), T₁ (0 mg PN + endosulfan), T₂ (10 mg PN + endosulfan), T₃ (50 mg PN + endosulfan), T₄ (100 mg PN + endosulfan) and T₅ (200 mg PN + endosulfan). Weight gain (%), specific growth rate (SGR), tissue glycogen, and protease activity were significantly (P < 0.05) higher in pyridoxine fed groups compared to their non-pyridoxine fed counterpart. Protease activity was positively correlated (R² = 0.931) with (%) weight gain. Glucose-6-phosphate dehydrogenase (G6PDH) activity was significantly (P < 0.05) higher in non-pyridoxine fed group and decreased in pyridoxine fed counterparts. There were no significant (P > 0.05) effect of dietary pyridoxine on feed conversion ratio (FCR), protein efficiency ratio (PER), survival, gastro-somatic index (GSI), hepato-somatic index (HSI) and liver and muscle DNA levels of L. rohita fingerlings. RNA levels, both in liver and muscle, increased significantly (P < 0.05) in pyridoxine fed groups. A positive correlation was observed between growth and RNA levels, both in liver (R² = 0.91) and muscle (R² = 0.88). RNA/DNA ratio showed a third order polynomial relationship with dietary pyridoxine, both in liver (Y = −0.014x³ + 0.1613x² − 0.5333x + 0.7933, R² = 0.987) and muscle (Y = −0.0407x³ + 0.4763x² − 1.6358x + 2.4667, R² = 0.9345). The overall results obtained in present study indicated that dietary pyridoxine supplementation at 100 or 200 mg PN/kg diet ameliorates the negative effects of endosulfan and restores optimal growth of L. rohita fingerlings.