Maternal variation in juvenile survival and growth of triploid hybrids between female rainbow trout and male brown trout and brook charr

Related sib‐groups of rainbow trout × brown trout and rainbow trout × brook charr triploid hybrids and monospecific diploid and triploid rainbow trout controls were obtained from a common set of rainbow trout dams. On the basis of hybrid juvenile performances, 10 sib‐groups were selected and the corresponding diploid rainbow trouts were raised up to adult stage. Females from each group of rainbow trout were used to produce a second generation of hybrid progeny, the performances of which were analysed for grandmaternal variation and relation with first‐generation relatives. Results showed that hybrid traits (alevin yield and weight, survival and growth of fingerlings) were strongly influenced by maternal origin, and could be correlated to those of rainbow trout controls, but that maternal abilities had a low rate of inheritance. It was concluded that little improvement can be expected through selective breeding within parental populations.     

Effect of feeding schedule on growth of rainbow trout

Rainbow trout (Oncorhynchus mykiss) fingerlings were reared for 2 months under one of two different feeding regimes (one and two diurnal peaks) and under a constant feeding regime as a control in order to find out if it is possible to fit the feeding to the assumed circadian rhythm. The differences in the specific growth rates observed between the different feeding treatments were not significant, but the tank-effect and the effect of the genetic background of the fish were highly significant. The conclusion that no beneficial effects are achievable through alteration of the feeding regime and the significance of a possible genotype-feeding-regime interaction are discussed.     

Evidence of concealment behavior by adult rainbow trout and brook trout in winter

Abstract – There has been little investigation of the winter ecology of adult trout during winter, especially in regard to concealment behavior. We compared day vs night underwater counts of adult rainbow trout and brook trout from four streams. At water temperatures between 1°C and 9°C, daytime counts accounted for 44% and 16% of nighttime snorkeling counts for rainbow trout and brook trout adults, respectively. As winter progressed, nighttime counts declined more so for brook trout than rainbow trout, but the decline was not significant for either species. Nocturnalism of both species was higher in streams with colder water temperatures. We observed few fish within concealment structure; however, by electrofishing concealment habitat during the day, we captured 10 times more adult trout than we counted immediately beforehand by snorkeling. Adult trout were concealed in cobble-boulder substrate and woody debris during the day. ^Note     

Association between initial weight and weight gain in brook trout, Salvelinus fontinalis Mitchill, and brown trout, Salmo trutta L.

Abstract. Individual weighings of samples of brook trout, Salvelinus fontinalis Mitchill, and brown trout, Salmo trutta L., al the initiation and termination of their growth period, enabled estimating the association of weight gain on initial weight. In both cases the regressions were positive and the correlations significant. Variation in initial weight among tested individuals and groups is expected to bias growth estimates of these groups in programmes of genetic testing, as a result of this association. Obviating this bias requires an adequate correcting technique, involving the estimation of an environmentally generated correction factor. Phenotypic regression coefficients, as estimated in this investigation, cannot serve as correction factors, but may be regarded as maximum estimates.     

Variation in growth rate,liver weight and body composition at first sexual maturity in rainbow trout

Rainbow trout around 743 g were fed four different diets over an 8-month period. Maturing males grew faster in the period before spawning (Sept.–Dec.) than maturing females, and significantly faster than immature fish. Mature fish stagnated in growth while the immature fish surpassed the growth of mature fish during the spawning season. The condition factor was moderately influenced by the maturation process. In the period before spawning (Sept.–Jan.) maturing females had a significantly higher hepatosomatic index than males and immature fish. An increase in dry matter and fat and a decrease of protein were observed in the muscle of maturing males and immature fish towards the spawning season, while maturing females had a slight fall in dry matter and fat and a small increase in protein in the same period. Dry matter and fat in muscle of rainbow trout were positively correlated.     

虹鳟体质量和主要体尺性状异速生长的遗传分析

采用联合异速生长遗传模型,对中国水产科学研究院黑龙江水产研究所渤海冷水性鱼类试验站培育的F1杂交虹鳟(Oncorhynchus mykiss)和F2杂交虹鳟的体质量和体尺性状异速生长进行了遗传分析,旨在为虹鳟及其他水产动物异速生长的遗传参数估计和实现体质量与体型的同步选育奠定理论基础。首先采用逐步回归分析法选择体尺性状对体质量的异速生长显著的性状,建立最优表型联合静态、动态异速生长指数模型,随后构建了两个用于遗传分析多个静态、动态异速生长的随机回归模型。虹鳟多个体尺性状相对体质量的异速生长遗传分析结果表明,体长与体质量具有较大的异速生长指数,为1.633 8,且为正异速生长,而其他体尺性状相对体质量呈现负异速生长;遗传方差大小顺序和表型的偏异速生长指数一致,体宽和背鳍基长的异速生长的遗传相关最大,为-0.867 5,其次为体长和体高,为-0.619 4,最小的是-0.021 7,为体高和体宽。体长与体质量的动态异速生长的加性遗传方差估计值为0.292 9。结果表明,虹鳟体质量和主要体尺性状的异速生长是由遗传机制决定的,遗传方差及遗传相关的估计能够用来筛选优良亲本,这为进一步利用异速生长理论指导虹鳟及其他水产动物体质量与体型的同步选育提供了理论基础。     

The combined effects of feeding time and dietary fat levels on feed intake,growth and body composition in rainbow trout

The combined effects of feeding time (morning and evening) and dietary fat concentration on feed intake, growth, body composition and lipid tissue distribution were examined in rainbow trout fed on demand. To that purpose, diets with low (LE, 6% lipid) or high energy concentrations (HE, 24% lipid) were used in four treatments that combined provision of the same (HE–HE or LE–LE) or different (HE–LE, LE–HE) diets at morning and evening meals. Digestible energy intakes of the LE–HE (229 kJ kg^–1 d^–1) and HE–HE (269 kJ kg^–1 d^–1) groups were significantly different. There was no significant difference in the amount of energy intake between the two meals of the day in any of the treatments. The main effect of dietary treatment was on lipid intake; fish in the HE–HE, HE–LE and LE–HE treatments ingested approximately 3, 2.2 and 1.8 times more lipid than those on the LE–LE treatment. Growth, weight gain and protein gain were not affected by dietary treatment, but lipid gain reflected lipid intake; fish in the HE–HE, HE–LE and LE–HE treatments gained approximately 2.6, 2.1 and 1.7 more lipid than did fish on the LE–LE treatment. Body composition was significantly affected by dietary treatment; whole body lipid content reflected lipid gain, and visceral lipid concentration was affected in a similar way to whole-body lipid. On the other hand, muscle lipid concentrations were similar in fish submitted to the HE–LE, LE–HE, and LE–LE treatments (< 4%), and were lower than in fish on the HE–HE treatment (ca. 5.5%). Consequently muscle lipid concentration was not directly related to lipid intake, because lipid intakes of fish on HE–LE and LE–HE treatments was higher than in those on the LE–LE treatment, while muscle lipid concentration was lower. Thus feeding fish with different diets in the morning and evening might have potential as a tool for manipulating lipid distributions and concentrations without major adverse effects on growth.     

Effects of feeding frequency on food intake,growth and body composition of rainbow trout (Salmo gairdneri)

The effects of feeding frequency on food intake, weight change and relative proportions of the major body components were investigated at 10°C in a strain of hatchery-reared rainbow trout. Feeding frequencies were from one meal every second day to six meals per day, within the range common to current piscicultural techniques. Fish were fed a dry, pelleted diet either to satiation at each meal, or in restricted total daily amounts based on a percentage of their wet body weight. All fish were forced to swim at a constant speed of approximately one body length per second to minimize variability in growth and body composition.Maximum daily food intake occurred with just two feedings to satiation per day. Growth closely paralleled food intake. Neither specific growth rate nor whole body levels of moisture, lipid or protein were affected significantly by differences in feeding frequency. A trend towards increased body fat with more frequent feeding was observed among fish fed to satiation at each meal; this was believed to be the result of a somewhat higher total food intake than among less frequently fed fish. Fish fed a restricted daily ration divided into a number of meals exhibited smaller differences in lipid content.The general lack of response to feeding frequency was attributed primarily to the low metabolic rate of trout and to the characteristically slow rate of food passage in the digestive tract.     

虹鳟鱼颗粒饲料投喂技术

鱼种和饲料是养鱼的物质和能量基础，良好的水质是生产的有利条件，除此之外，投喂是最重要的饲养技术。为了获得较好的饲养和饲料效果，降低养殖虹鳟鱼成本，投喂时应注意以下几点问题： １．饲料的形状、结构和规格不仅影响适口性，也影响消化率，选择投喂的颗粒饲料的大小要注重适合各生长阶段鱼吞食。在虹鳟鱼喂养中，12g以下的鱼苗鱼种，根据其个体大小可选择O．3mm－2．2mm粒径大小的颗粒饲料投喂；12g～60g的鱼种可分别选择 2．2mm－3.2mm粒径，长度3mm－4mm的颗粒饲料投喂；60g-195g的鱼种可分别选择3.5mm4．5mm粒径，长度4mm-5mm…     

Fin condition and growth among rainbow trout reared at different sizes,densities and feeding frequencies in high-temperature re-circulated water

Rainbow trout were studied at different rearing densities, fish sizes and feeding frequencies so that we could evaluate the effect of these parameters on fin condition, growth and feed utilisation. In one study, two sizes of rainbow trout (18–70 g or 48–125 g), fed to near satiation at 17.7°C, were examined at two rearing densities (11–41 kg m⁻³ or 21–92 kg m⁻³). This study showed that the anal fin was healthier (P < 0.05) at low densities. In the second study rainbow trout were again fed to near satiation and grown from 50 g to 125 g in 16.4°C water, and they were fed either once daily or three times daily at two densities (18–45 kg m⁻³ or 54–124 kg m⁻³). Rainbow trout growth and feed utilisation were slightly but significantly (P < 0.05) reduced at high densities, while dorsal fin condition, surprisingly, was better (P < 0.0001) at the high densities. Possible explanations to these findings are discussed. Condition of the left pectoral fin was improved at once daily feeding (P < 0.05) compared with three feedings per day, at which fights for feed possibly are more frequent.     

Carbohydrate in rainbow trout diets: Effects of the level and source of carbohydrate and the number of meals on growth and body composition

Isonitrogenous rations containing various levels of digestible carbohydrate were fed to groups of trout for 8 weeks. Two levels (15 or 30%) and two sources (glucose or starch) of carbohydrates were used. A given amount of a 30% glucose diet was distributed in either 2, 4 or 6 meals/day, to determine the effect of meal frequency.Growth, feed efficiency and body composition of the different groups were compared. Glycaemia levels, as influenced by the different dietary treatments, were measured immediately and 6 h after a given meal.The 30% glucose diet promoted the best weight gain, feed conversion and protein efficiency. Groups fed the 15% glucose diet gave values between those of the 30% glucose and the 30% starch-fed groups. The additional energy retained in groups fed the highest glucose level (30%) did not modify carcass composition but increased fat deposits in the viscera and glycogen in the liver. Plasma glucose levels indicated that the regulation of glycaemia is effective within a 24-h period, even after a daily intake of 550 mg glucose/100 g body weight. Increasing the number of meals had no discernible effect, the efficiency of the 30% glucose diet being the same in the various groups.It is concluded that, under certain experimental conditions, trout can tolerate up to 30% glucose in the diet and can use it for energy needs.     

Spatial and temporal variation in brook trout and brown trout proportional stock densities in Wisconsin streams

Abstract  Proper interpretation of measures used to describe fish populations requires knowledge of the measure's inherent spatial and temporal variation. Proportional stock density (PSD), the ratio of 'quality-length' fish to 'stock-length' fish multiplied by 100, is commonly used as a measure of population size structure; PSD values range from 0 to 100. Spatial and temporal variation in brook trout, Salvelinus fontinalis (Mitchill), and brown trout Salmo trutta L., PSD scores in Wisconsin are described and tested to determine if variation differed by stream order and ecoregion. Neither stream order nor ecoregion significantly affected variation of PSD scores. The mean standard deviation of PSD scores over time at a site was 12.49 for brook trout populations and 12.95 for brown trout populations. The mean standard deviation of PSD scores between sites in the same stream was 15.07 for brook trout populations and 12.50 for brown trout populations. Sampling frequency required to characterise a PSD score of a single population of trout in Wisconsin streams with a degree of precision equal to the amount of observed temporal variation is approximately 14 sites for brook trout and 20 sites for brown trout.     

(革丽)靬金鳟和虹鳟生长对比试验

革丽革干金鳟是红鳟的一个变异种 ,由甘肃省永昌金鳟鱼培育繁殖中心于上世纪末培育成功 ,具有良好稳定的遗传性。经 2 0 0 0年 11月 2 2日农业部专家组鉴定 ,取名为“永昌金鳟一号”。与日本金鳟相比 ,其体色更加金黄艳丽 ,眼球血红 ,集食用和观赏价值于一体 ,目前市场售价是虹鳟的 2～ 3倍。作者就其生长性能与虹鳟作了对比试验 ,以期为我省推广养殖该鱼提供参考。1　试验材料1 1　鱼池　试验用鱼池为榆中县虹鳟鱼试验场7#、 8#鱼苗池 ,两池并联 ,为长方形水泥池 ,大小相同 ,长 6m ,宽 1 5m ,深 0 5m ,面积 9m2 。鱼池进水口与最高水位有 …     

Digestive characteristics and blood chemistry profile of triploid rainbow trout Oncorhynchus mykiss: influence of body size and seasonal variation

Fisheries Science - Two experiments were conducted to evaluate the effects of body size and seasonal variation on organ indexes, digestive enzymes and plasma biochemistry parameters of triploid...     

5个虹鳟群体的生化遗传分析

虹鳟(Oncorhynchus mykiss)系山河流中的冷水性鱼类,属鲑形目、鲑科、大麻哈鱼属。从20世纪90年代起,黑龙江水产研究所陆续从国外引种芬兰虹鳟、道氏虹鳟、挪威虹鳟、丹麦虹鳟和美国加州虹鳟,经多年选育养殖成功,为我国冷水鲑鳟增养殖及游钓业增加了新品种。目前,关于虹鳟生殖[     

Influence of the combination of time of feeding and ration level on the diurnal hormone rhythms in rainbow trout

The study examined the combined effects of time of feeding (post-dawn, midday-pre-dusk) and ration level (1.5%, 2.0%, 2.5%) on the diurnal rhythms of plasma growth hormone (GH), L-thyroxine (T₄), triiodo-L-thyronine (T₃), cortisol and glucose concentrations in rainbow trout (Oncorhynchus mykiss) maintained under constant ambient water temperature and natural photoperiod.Plasma GH and glucose concentrations exhibited marked diurnal rhythms, with significant postprandial peaks that were phase-shifted with time of feeding. The ration level did not appear to alter these feeding time-entrained rhythms, but the amplitude of the changes (peaks) were more pronounced in trout fed the higher ration levels. Plasma cortisol concentrations showed distinct diurnal rhythms, with peaks during the photophase and the scotophase in all the treatment groups. The time of feeding did not appear to influence these rhythms, and there was no evidence of a postprandial increase in any group.Plasma GH, cortisol and glucose concentrations were significantly higher in groups fed the 2.5% ration compared with animals fed either 1.5 or 2.0% rations.The diurnal rhythms of plasma T₄ concentrations were not affected by the time of feeding or ration level; the peak values generally occurred during the photophase in all the treatment groups. Plasma T₃ concentrations did not show any significant diurnal patterns, nor were they influenced by ration levels or time of feeding.To whom correspondence should be addressed     

Genetic studies of growth in domesticated rainbow trout

The heritability of body weight and the form of the growth curve was investigated in two crossbred strains of domesticated rainbow trout. Growth rate was nearly exponential at young ages but slowed to nearly linear at older ages. An empirical equation was derived that related exponential growth constants to the observed growth patterns. Heritabilities of body weight based on full-sib families were estimated at six ages for each stock. Estimates made at young ages were similar to other estimates of body weight in salmonid fish. However, non-additive genetic variance, culling bias and common environmental effects may have inflated estimates made at older ages, as the estimates were extremely high, and these possible sources of confounding were known to exist in the experimental design.     

Effect of feeding level on growth and nutrient deposition in rainbow trout (Oncorhynchus mykiss Walbaum) growing from 150 to 600 g

The effects of feeding level on growth and energy partitioning were studied in rainbow trout growing from 150 to 600 g. Triplicate groups of fish (initial weight 158 g fish^?1) were fed a practical diet at various feeding levels (25%, 50%, 75% and 100% of near satiation) for 24 weeks at 8.5°C. The final body weights of fish were 235, 381, 526 and 621 g. Restricted feeding levels significantly reduced live weight gain. Feeding levels had less pronounced effects on feed efficiency ratio, which were 0.98, 1.08, 1.02 and 0.83, respectively, for the 25%, 50%, 75% and 100% feeding levels. The growth of fish fed to near satiation was accurately described by the thermal‐unit growth coefficient. The growth data also showed that the widely used specific growth rate was not an appropriate model. Fish fed at the lowest feeding level (25%), which represented a maintenance ration (energy gain was less than 2 kJ fish^?1 day^?1), showed positive protein deposition but negative lipid deposition. This indicates that fish fed a maintenance ration mobilize body lipid reserve to support protein deposition. The efficiency of energy for growth (k_g) was estimated to be 0.63. The factorial multiple regression approach estimated that the partial efficiencies of metabolizable energy utilization for protein deposition (k_p) and lipid deposition (k_f) were 0.63 and 0.72, and that maintenance energy requirement was about 19 kJ (kg BW^0.824)^?1, for rainbow trout held at 8.5°C.