Feeding selectivity in early life stages of Rhamdia voulezi under experimental conditions

The feeding selectivity of laboratory‐reared larvae of Rhamdia voulezi was assessed to investigate the preferred preys in early life stages. Three experiments were conducted at different larval development stages, starting soon after the absorption of the yolk sac (on fourth day after hatching – DAH), using zooplankton from fish ponds as food. Differences were detected in the patterns of prey selection among development stages. At first, the larvae prefer small preys, such as rotifers and cladocerans. Later, when they are more developed, they prefer to feed on large preys, such as copepods. On the fourth DAH, larvae in the pre‐flexion and initial flexion stage strongly selected rotifers and cladocerans (Diaphanosoma spinulosum, D. brevireme, Moina sp., M. micrura and M. minuta). At the other stages, cladocerans continued to be strongly selected. However, on the eighth DAH, larvae in flexion stage selected less strongly copepods Argyrodiaptomus azevedoi, Metacyclops mendocinus and Termocyclops decipiens. On the tenth DAH, larvae in postflexion stage selected more strongly copepods Argyrodiaptomus furcatus, Notodiaptomus cf. spinuliferus and M. mendocinus. As larvae grow, they tend to specialize in feeding of a particular prey. Prey selection of R. voulezi larvae was based both on species and zooplankton size. The size of the zooplankton ingested was related to the mouth gape size of larvae.     

长江口斑尾刺虾虎鱼的摄食习性

2014年6月至2015年5月,在长江口东旺沙、东风西沙和青草沙潮间带水域隔月进行插网作业,共采集到459尾斑尾刺虾虎鱼(Acanthogobius ommaturus)样品,分析其胃含物。结果表明,斑尾刺虾虎鱼共摄食12类37种生物,主要摄食虾类,其次是鱼类、蟹类等。其饵料生物组成随季节和体长的不同而有所变化,除四季均大量摄食虾类以外,春季还摄食糠虾类和蟹类,夏季还摄食鱼类,冬季还摄食糠虾类;体长70 mm的斑尾刺虾虎鱼主要以幼鱼为食,同时还摄食大量的糠虾类和磷虾类,体长70~189 mm的个体主要摄食虾类和鱼类,体长189 mm的个体主要以鱼类为食。聚类分析结果表明,斑尾刺虾虎鱼秋季的饵料生物组成与春、夏、冬季相比,存在较大差异;体长70 mm的斑尾刺虾虎鱼食物组成与体长≥70 mm相比,存在较大差异。斑尾刺虾虎鱼的摄食强度也有显著的季节和体长变化,Kruskal-Wallis非参数秩检验结果表明,不同季节组和体长组平均胃饱满系数均差异显著(P0.01);列联表检验结果表明,不同季节斑尾刺虾虎鱼的空胃率不存在显著差异(P0.05),不同体长组空胃率差异显著(P0.01)。通过计算Spearman等级相关系数得到饵料生物体长与斑尾刺虾虎鱼体长之间呈显著的正相关(rs=0.263,P0.01)。此外,摄食饵料平均重量和个数随着斑尾刺虾虎鱼体长的增大而增大,符合"最佳摄食理论"。因此,斑尾刺虾虎鱼的摄食习性不仅与环境中饵料生物丰度有关,也与其自身生长发育有关。     

实验室中海胆的人工授精及幼体培育

海胆作为实验材料需在实验室条件下进行人工授精和培育。本文介绍了实验室中海胆人工授精的方法,从受精卵到稚海胆各发育阶段的培育条件的培育方法。     

Feeding of Atlantic salmon, Salmo salar L., parr in the subarctic River Teno and three tributaries in northernmost Finland

Abstract— Available food and feeding of Atlantic salmon parr were studied in different parts of a subarctic river in northernmost Finland, the River Teno: in the large main stem, in a major tributary influenced by lakes, and in two minor tributaries. The highest density of benthic organisms was found in an outlet of a lake, but drifting organisms were the most abundant in the small tributaries. Migrant parr that move to the small tributaries from the main stem have better food resources in their new habitat. Plecoptera nymphs were the most important prey for salmon parr early in the spring. Later in the summer dipterans were usually the dominant prey group. In September the importance of Plecoptera was emphasized in the small tributaries and the lake outlet, and that of Trichoptera in other sites. Drifting prey was used more by large than by small parr. The utilization of drifting food appeared to be related to the water temperature rather than to the availability of the drift.     

池养条件下瓦氏黄颡鱼仔稚鱼摄食节律和日摄食率研究

对池养条件下瓦氏黄颡鱼(Pelteobagrus vachelli)早期发育阶段的摄食节律进行了研究。结果表明:每日5:00~9:00及17:00~21:00瓦氏黄颡鱼的饱满指数相对较高,15:00~17:00最低,表明瓦氏黄颡鱼属于晨昏摄食型;在仔鱼出膜后的第5、10、15、20、25和30天瓦氏黄颡鱼的日摄食率分别为44.79%、33.72%、23.21%、19.92%、16.58%和10.27%,呈逐渐下降趋势。     

鱼用促摄食物质研究方法

近些年,鱼粉的价格持续走高,使寻找优质高效的廉价替代蛋白源成为必然趋势。替代蛋白的使用又引起配方饲料诱食性和适口性下降的问题。因此,自20世纪70年代起,国内外学者进行了大     

海蜇不同生长阶段的摄食方式和摄食习性

实验室观察海蜇螅状体、碟状体、水母体生长阶段的摄食方式和摄食习性.观察结果表明,海蜇各生长阶段的摄食方式不同,螅状体依靠触手捕获食物,碟状体依靠缘瓣捕获食物,水母体依靠口腕和肩板表面上的吸口完成.三者的摄食习性大致相同,摄食活动昼夜不间断进行,摄食习性是被动性的,对食物的种类只是规格大小的选择.食物规格＜1 mm,最大...     

Establishing larval feeding regimens for the Forktail Blenny Meiacanthus atrodorsalis (Günther, 1877): effects of Artemia strain,time of prey switch and co‐feeding period

This study aimed to establish feeding strategies covering the whole larval period of the forktail blenny, Meiacanthus atrodorsalis, based on the standard hatchery feeds of rotifers and Artemia. Three purposely designed experiments were conducted to determine the appropriate times and techniques to transition larvae from rotifers onto Artemia nauplii of a Great Salt Lake (GSL) strain, and a specialty AF strain, as well as subsequent transition onto enriched metanauplii of GSL Artemia. With a 3‐day co‐feeding period, larvae adapted well to a transition from rotifers to newly hatched GSL Artemia nauplii as early as 5 days posthatching (DPH), and as early as 3 DPH when fed the smaller AF Artemia nauplii. However, prolonging the rotifer‐feeding period up to 11 DPH did not negatively affect survival. Larvae fed Artemia nauplii of the AF strain showed 17–21% higher survival, 24–33% greater standard length and body depth, and 91–200% greater dry weight, after 20 days relative to those fed nauplii of the GSL strain. Meanwhile, enriched Artemia metanauplii of the GSL strain were shown to be an acceptable alternative to AF Artemia nauplii for later larvae, producing similar survival and growth when introduced from 8 DPH. Based on our findings, we recommend feeding M. atrodorsalis larvae rotifers as a first food between 0 and 2 DPH, introducing AF Artemia nauplii from 3 DPH, followed by enriched GSL Artemia metanauplii from 8 DPH onward, with a 3‐day co‐feeding period between each prey change.     

Behavioral changes associated with suboptimal prey densities for larval American shad

Laboratory studies were conducted to determine the effects of suboptimal prey density and length of prey-deprivation period on swimming, feeding, and social behavior in larval American shad. Alosa sapidissima. Replicated prey-density treatments of 1,000, 500, and 0 Artemia nauplii/liter and deprivation periods of 0,2, and 4 days were established for an 8-day period. The duration or frequency of 11 behavior patterns was quantified with an event recorder during the experiment. Exposure to suboptimal prey densities affected three categories of larval behavior: swimming activities (pivot and dart), interaction with other larvae (escape or avoid), and stereotypical feeding responses (sigmoid and lunge). Location of a food patch, simulated by the sudden introduction of prey to aquaria, affected the frequency of feeding responses more than other categories of behavior. The patch model was supported as a foraging strategy in larvae. The ontogeny of prey deprivation was evidenced primarily by changes in swimming activity (reduced pivot and dart frequencies), though feeding responses (particularly fixate) were also diminished. Deprivation-induced loss of pivot and fixate was an irreversible, pathological effect of starvation. Deprivation also resulted in greater vertical orientation (head up, 42°) of larvae than non-deprived larvae (21–29°). These changes in behavior may result in less effective escape from predators, location of food patches, or pursuit and capture of prey items in riverine habitats.     

海州湾秋季小眼绿鳍鱼的摄食策略及食物选择性

基于2011年及2013—2015年秋季在海州湾海域进行底拖网调查数据,通过分析733尾小眼绿鳍鱼(Chelidonichthys spinosus)的胃含物样品,对其食物组成、摄食强度、摄食策略以及食物选择性等摄食生态特征进行初步研究。结果表明,小眼绿鳍鱼摄食饵料生物共有80余种,其中优势饵料种类为细螯虾(Leptochela gracilis)、戴氏赤虾(Metapenaeopsis dalei)、疣背宽额虾(Latreutes planirostris)、双斑蟳(Charybdis bimaculata)、细条天竺鲷(Apogon lineatus)等。聚类分析结果显示,小眼绿鳍鱼的食物组成无明显体长变化。不同体长组小眼绿鳍鱼的空胃率差异不显著(P0.05),平均胃饱满指数差异显著(P0.05)。广义加性模型(GAM)分析表明,底层盐度、底层水温和纬度对小眼绿鳍鱼的摄食强度有显著影响(P0.05),而体长、经度和水深的影响则不显著(P0.05)。摄食策略分析表明,小眼绿鳍鱼是以虾类和鱼类为主要饵料类群的广食性鱼类。通过计算食物选择性指数发现,小眼绿鳍鱼喜食饵料与实际摄食的主要饵料种类存在一定差异,表明其摄食既具有较强的主动选择性,同时又受到海州湾饵料丰度和可获得性等因素的影响。     

The role of temperature in the prey capture probability of drift‐feeding juvenile brown trout (Salmo trutta)

Abstract – Cold water temperatures are widely supposed to reduce the food intake of stream salmonids. Although cold temperatures have been documented to reduce swimming ability, digestion and gastric evacuation rates, little is known about how temperature influences the ability of fish to capture prey. We examined the effects of water temperature on the prey capture probability of drift‐feeding juvenile brown trout (Salmo trutta) in a laboratory stream. Temperatures ranged between 5.7 °C and 14 °C. We found significant effects of water temperature on prey capture probability and capture manoeuvre time. The mean capture probability dropped from 96% at 14 °C to 53% at 5.7 °C. At 8 °C and higher temperatures, foraging performances did not differ much among treatments. We suggest that reduced swimming ability could be one of the most important mechanisms for the observed pattern of reduced prey capture probability at cold water temperatures, but prey detection limitations and predator avoidance may play a role. Our results will be of use for bioenergetics‐based drift‐foraging models, which to date have not incorporated a temperature‐dependent prey capture function.     

栉江珧(Atrina pectinata)催产方法及幼虫培养条件

为探究江珧亲贝的最佳催产方法及减少工厂化育苗过程中栉江珧幼虫上浮粘连现象,分别研究了不同催产方法对受精率和胚胎发育的效果,不同培育密度和培育方式对幼虫生长发育的影响。结果显示,阴干4 h后用升温3℃的次氯酸钠中和海水,可诱导亲贝大量排放精卵。并且对卵子受精及胚胎发育影响较小。幼虫培养实验结果显示,幼虫最适培育密度为1 ind/ml,在降低幼虫培育密度的同时,在培育池内安装造浪泵,使培育水体流动起来,能够有效减少幼虫的相互粘连提高幼虫的成活率。     

Effects of prey nutritional quality on the growth and survival of juvenile cuttlefish, Sepia officinalis (Linnaeus, 1758)

This investigation examined the effect of prey condition on the growth and survival of juvenile cuttlefish ( Sepia officinalis ). In the first group, cuttlefish were fed with daily captured live Palaeomonetes varians from the wild [daily prey (DP)], the second group was fed 5 days stocked and starved P. varians [starved prey (SP)], while in the third group, cuttlefish were fed 8 days stocked P. varians fed with an artificial diet [fed prey (FP)]. Mean instantaneous growth rate (IGR) was 2.8±1% body weight day⁻¹ (bw day⁻¹), 3.3±1.1% bw day⁻¹ and 4.9±0.5% bw day⁻¹ for SP, DP and FP respectively. At the end of the experiment, final weight gain ( W _g) was 121±21.6%, 153.8±17.3% and 295±29.8% for SP, DP and FP respectively. No significant differences were found ( P >0.05) between growth curves for every group tested, or for the food conversions between those same groups ( P >0.05), but statistical differences ( P <0.05) were found in IGR between DP vs. FP and SP vs. FP. Mortality was 2 and 1 for SP and DP respectively. Results indicate that prey starvation should not be considered when feeding juvenile cuttlefish, as prey can only be stocked if proper artificial diets are provided, to obtain optimal growth.     

宝石鲈摄食节律和日摄食率的初步研究

为了解宝石鲈昼夜摄食规律和日摄食量,采用饱满度指数法在7-9月对124尾宝石鲈在不同昼夜节律下的摄食节律和日摄食率进行了研究。试验结果表明,9:00-17:00为摄食高峰期,凌晨1:00摄食活动最弱,翌日5:00摄食强度明显升高。7-9月,该鱼的日摄食率(用占体质量的百分比表示)分别为6.07%、3.34%、2.37%。宝石鲈有明显的摄食节律,属于白天摄食类型。     

湘云鲫食用鱼饲养和鱼种培育试验

４口池塘放养湘云鲫夏花鱼苗,经过１２０￣１５０ｄ的饲养,成鱼池主养平均规格达１９０ｇ和２２０ｇ;鱼种池主养平均规格达１２５ｇ和６５ｇ。每６６７ｍ＾２效益达２０００元以上。     

元江越鳠的食性研究

研究了越鳠的食物组成、摄食强度和摄食形态学。样本251尾,2008年6月~2009年5月采自云南元江。结果表明：越鳠的食物由水生昆虫幼虫和小型鱼类等15类组成,水生昆虫幼虫和小型鱼类的出现率分别为73.8%和64.2%,所占比重分别为40.0%和46.9%,小型鱼类和水生昆虫幼虫为越鳠的主要食物。随着体长增加,食物类别减少,摄食强度降低;水生昆虫幼虫的出现率降低,成虫出现率增加;体长160 mm以上个体胃中出现陆生昆虫且其出现率持续上升。食物组成的季节变化明显,摄食强度的季节变化不明显。越鳠是一种偏肉食性的杂食性鱼类,主要摄食底层小型鱼类和水生昆虫幼虫。     

额尔齐斯河东方欧鳊食性研究

通过分析额尔齐斯河东方欧鳊(Abramis brama)的食物组成、摄食强度和摄食策略,探究其在摄食形态学上的适应性,进一步补充和完善东方欧鳊生物学基础资料,为其人工增养殖提供技术支持。2014年5月至2015年6月,采用三层流刺网、定置刺网和围网,在额尔齐斯河中国段下游分季节连续采集东方欧鳊样本152尾。通过对鱼类样本进行测定、分析和处理,分别对东方欧鳊的摄食强度以及食物组成和摄食策略进行了研究。结果表明,152尾东方欧鳊样品的空肠率为30.92%。根据数量百分比分析,藻类在东方欧鳊食物组成中占绝对优势(99.82%),其中硅藻门的比例最高(73.09%);通过重量百分比、相对重要性指数百分比以及优势度指数指标分析,在每年的5-6月,额尔齐斯河东方欧鳊主要摄食水生昆虫幼体,以摇蚊幼虫为主,藻类在食物组成中的比重极小;Amundsen图示法表明,此时东方欧鳊为偏动物食性的广食性鱼类,且不同个体间食物组成存在一定差异。东方欧鳊的摄食消化器官形态与其食性相适应。     

人工育苗条件下的大黄鱼胚胎发育及其仔,稚鱼形态特征与生态的研究

连续观察人工育苗中同一批受精卵,在水温23.2～23.4、盐度27.00～27.80‰条件下,经过3h36min孵出仔鱼,并继续观察仔、稚鱼发育过程中的形态特征与生态习性。还比较了不同年份与不同批次的观察资料,讨论了水温等环境条件变化对胚胎发育的影响,以及仔、稚鱼器官发育与日龄、生长速度等关系。