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We evaluated the effect of ration level(RL) on the growth and energy budget of lenok Brachymystax lenok. Juvenile lenok(initial mean body weight 3.06±0.13 g) were fed for 21 d at five different ration levels: starvation,2%,3%,4% bwd(body weight per day,based on initial mean values),and apparent satiation. Feed consumption,apparent digestibility,and growth were directly measured. Specific growth rates in terms of wet weight,dry weight,protein,and energy increased logarithmically with an increase in ration levels. The relationship between specific growth rate in terms of wet weight(SGRw,%/d) and RL(%) was characterized by a decelerating curve: SGRw=-1.417+3.166ln(RL+1). The apparent digestibility coefficients of energy exhibited a decreasing pattern with increasing ration level,and there was a significant difference among different RLs. Body composition was significantly affected by ration size. The relationship between feed efficiency rate in terms of energy(FERe) and RL was: FERe=-14.167+23.793RL–3.367(RL)2,and the maximum FERe was observed at a 3.53% ration. The maintenance requirement for energy of juvenile lenok was 105.39 k J BW(kg)-0.80/d,the utilization efficiency of DE for growth was 0.496. The energy budget equation at satiation was: 100IE=29.03FE+5.78(ZE+UE)+39.56 HE+25.63 RE,where IE is feed energy,FE is fecal energy,ZE+UE is excretory energy,HE is heat production,and RE is recovered energy. Our results suggest that the most suitable feeding rate for juvenile lenok aquaculture for wet weight growth is 2.89% bwd,whereas for energy growth,the suggested rate is 3.53% bwd at this growth stage. 相似文献
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We conducted acoustical surveys with a horizontal beam transducer to detect fish and with a vertical beam transducer to detect depth and macrophytes in two typical shallow lakes along the middle and lower reaches of the Changjiang(Yangtze) River in November 2013. Both lakes are subject to active fish management with annual stocking and removal of large fish. The purpose of the study was to compare hydroacoustic horizontal beam estimates with fish landings. The preliminary results show that the fish distribution patterns dif fered in the two lakes and were af fected by water depth and macrophyte coverage. The hydroacoustically estimated fish biomass matched the commercial catch very well in Niushan Lake, but it was two times higher in Kuilei Lake. However, acoustic estimates included all fish, whereas the catch included only fish 45 cm(smaller ones were released). We were unable to determine the proper regression between acoustic target strength and fish length for the dominant fish species in the two lakes. 相似文献
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INTRODUCTION The eonversion of dietary Protein,liPid and earbohydrate in the body of thevertebrate 15 conneeted with the intermediate metabolism Proeesses in whieh themetalloenzymes Play very imPortant roles.Anderson et al.(1984)and Teshimaand Kanazawa(1 986)Proved the maintenanee of ProPer Protein and liPidlevelsin the diets eoneomitant with inereasing the dietary earbohydrate eontent to 40%ean Promote teh growth of Nile tilaPia fingerlings.EI一Sayed and Garling(1988)indi eated th… 相似文献
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湖北牛山湖高体鳑鮍的年龄、生长与繁殖 总被引：2，自引：0，他引：2
研究了牛山湖高体鳑鲏的年龄、生长和繁殖特征. 鳞片上年轮清晰,主要呈现疏密特征.种群年龄结构简单,仅由一个世代组成;雄与雌的比例为1.59∶1(n= 332),显著不同于1∶1(Xc2 ＝16.94, p<0.005)而符合2∶1的类型(Xc2 ＝3.82, p> 0.05). 两性最大寿命不超过2a.雄、雌体全长与体重、全长与体长的回归方程差异显著. 在繁殖期间,雌雄鱼均出现第二性征.雄鱼最小成熟个体的全长和体重分别为26mm、0.216g,雌鱼则分别为32mm、0.393g. 性成熟年龄为1a,属分批产卵类型.成熟卵粒呈葫芦状,长度平均3.31mm. 每尾雌鱼平均繁殖力为61粒,繁殖力与全长及体重均呈显著相关(p＜0.001). 相似文献
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本文对河蟹幼蟹蜕壳过程及蜕壳后的特征进行了比较详细的观察,并初步探讨了蜕壳与光照、温度及生境的关系对于0.5-2g的幼蟹,蜕壳期大约需要3-6h,软壳期需要2h,薄壳期需要15h．幼蟹特别喜欢选择有草的生境作为蜕壳地点,也喜欢在池塘浅水区蜕壳,但是在2m以内水深对蜕壳成功率没有影响．蜕壳存在明显的昼夜节律,白天蜕壳的数量显著高干夜间(F(1.30)=13.4,P=0.0009),蜕壳高峰发生在上午(07:00-11:00),低谷一般发生在夜间(23:00-03:00)．协方差分析（昼夜为协变量）表明：水温的昼夜变化(28-35℃)对蜕壳并没有显著的影响(F7,11=1.99,P=0.1467),在水温高达 35℃时蜕壳仍然能顺利进行,蜕壳下限温度在14℃左右。 相似文献
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图 3 卵粒大小的频数分布 (ａ)具成熟卵细胞 (ｂ)无成熟卵细胞Ｆｉｇ 3ＦｒｅｑｕｅｎｃｙｄｉｓｔｒｉｂｕｔｉｏｎｏｆｅｇｇｓｉｚｅｏｆＲｈｏｄｅｕｓｏｃｅｌｌａｔｕｓ(ａ)ｗｉｔｈｓｏｍｅｍａｔｕｒｅｅｇｇｓ ,(ｂ)ｗｉｔｈｏｕｔｍａｔｕｒｅｄｅｇｇｓ图 4繁殖力 (Ｆ ,ｅｇｇｓ)与体重 (Ｗ ,ｇ)及全长 (ＴＬ ,ｍｍ )的关系Ｆｉｇ 4Ｒｅｌａｔｉｏｎｓｈｉｐｂｅｔｗｅｅｎｆｅｃｕｎｄｉｔｙ (Ｆ ,ｅｇｇｓ)ａｎｄｂｏｄｙｗｅｉｇｈｔ (Ｗ ,ｇ)ｏｒｔｏｔａｌｌｅｎｇｔｈ (ＴＬ ,ｍｍ)湖北牛山湖高体鳑鮍的年龄、生长与繁殖@… 相似文献
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于2008-2009年按照季节调查了西藏尼洋河浮游植物群落的组成、丰度和多样性,并运用多元统计方法定量分析了浮游植物的空间和季节变化特征及其与主要环境因子之间的关系.结果显示,尼洋河浮游植物共计7门29科48属,其中硅藻为优势浮游藻类.浮游植物Shannon-Wiener多样性指数(Pielou均匀度指数)在尼洋河中游(尼洋河下游)最高,其他河段呈下降趋势,符合中间高度膨胀假说.尼洋河沿程浮游植物的总丰度、物种丰富度、Shannon-Wiener多样性指数以及Pielou均匀度指数不存在显著差异,夏季的浮游植物物种丰富度与其他季节的存在显著差异,夏季总丰度与秋、冬季的存在显著差异,冬季的浮游植物Shannon-Wiener多样性指数与春季的存在显著差异,冬季的均匀度指数与其他3个季节的存在显著差异.尼洋河浮游植物季节演替依赖于外源性水源补充,沿程演替则与河道底质有着很大关系.典范对应分析(CCA)表明,尼洋河硅藻门舟形藻科的藻类与理化因子铵态氮、表层pH、表层水温相关,部分蓝藻以及绿藻与水质理化因子也存在着关联.分类回归树(CART)模型预测了尼洋河着生藻类时空分布与主要环境因子之间的定量关系,尼洋河浮游植物群落总丰度和均匀度指数受pH值影响较大,pH值低于8.0的水域浮游植物均匀度指数比pH值高于8.0的水域大,尼洋河浮游植物Shannon-Wiener多样性指数受到河道底质影响较大,底质为黏土的水域浮游植物Shannon-Wiener多样性指数较底质为砂石的大.这些关键环境因子对尼洋河水域浮游植物的时空变化有着重要的指示作用,建议加强对浮游植物及这些环境因子的关注,保障尼洋河水域生态环境的可持续发展. 相似文献
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Cyanobacterial blooms occur frequently in lakes due to eutrophication. Although a number of models have been proposed to forecast algal blooms, a good and applicable method is still lacking. This study explored a simple and effective mathematical-ecological model to evaluate the growth status and predict the population dynamics of Microcystis blooms. In this study, phytoplankton were collected and identified from 8 sampling sites in Chaohu Lake every month from July to October, 2010. The niche breadth and niche overlap of common species were calculated using standard equations, and the potential relative growth rates of Microcystis were calculated as a weighted-value of niche overlap. In July, the potential relative growth rate was 2.79 (a.u., arbitrary units) but then rapidly declined in the following months to -3.99 a.u. in September. A significant correlation (R=0.998, P<0.01) was found in the model between the net-increase in biomass of Microcystis in the field and the predicted values calculated by the niche model, we concluded that the niche model is suitable for forecasting the dynamics of Microcystis blooms. Redundancy analysis indicated that decreases in water temperature, dissolved oxygen and total dissolved phosphorus might be major factors underlying bloom decline. Based on the theory of community succession being caused by resource competition, the growth and decline of blooms can be predicted from a community structure. This may provide a basis for early warning and control of algal blooms. 相似文献
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从渔业与环境兼顾的角度出发作者认为湖泊渔业可持续发展的生态学理论基础是渔业生态学和渔业湖沼学. 前者是一门较为成熟的学科研究渔业对象的种群生态学渔产潜力最佳放流密度和规格以及科学的捕捞策略等. 后者研究渔业对湖泊生态系统生物多样性和水质的影响并确定最佳的渔业规模和渔业方式但尚未提出令人满意的理论和完善的实验方法今后应予充分重视. 长江中下游草型湖泊因为其优良的水资源和丰富的生物资源而成为我国内陆水体发展优质高效渔业的重要基地. 以湖北一个浅水草型扁担塘渔业实践为例作者着重强调生态学管理的如下方面1) 沉水植被是草型湖泊优质高效渔业持续发展的基础必须在合理利用的同时加以保护优化甚至重建使生物量和覆盖率保持和达到一定水平. 2) 食物链网的基础环节是渔业对象生长和繁衍的物质基础, 必须进行培育保护以提高其生产力从而为提高渔业产量打下物质基础. 3) 合理放养与捕捞策略是湖泊渔业生态系统良性循环的可靠保证应使高价值的种群规模保持较大水平的输出. 相似文献