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黄金鲈与伊犁鲈杂交后代在气提泵循环水养殖系统中生长分析 总被引：1，自引：0，他引：1
研究通过黄金鲈(Perca flavescens)雌鱼与伊犁鲈(Perca schrenki)雄鱼进行杂交,以期加快鲈鱼的生长速度,推迟其性成熟和提高上市规格.为减少饲养环境条件和人为管理差异造成生长试验误差,研究采用试验鱼同池混养的方法进行生长比较.在气提泵循环水养殖系统中,经690 d的生长比较试验.结果表明:杂交鲈体重增长比黄金鲈快33.91%;杂交鲈的性腺发育被推迟或性腺发育不良;黄金鲈和杂交鲈的成活率分别为87.50%和82.08%,二者在成活率上无显著差异(P=0.29).杂交鲈适宜在高密度循环水养殖条件下生长,杂交优势较为显著,可以取代黄金鲈进行集约化养殖生产. 相似文献
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美国海淡水养殖新品种介绍-南方鲆 总被引：2，自引：0，他引：2
自1995年起，美国科学家对南方鲆开始了养殖方面的研究，因为它是世界闻名的高档鱼类，适温广，生长快，既可以在海水生活，又可在淡水里生长。这样，很多人预见在海水育苗后，转移到生产成本比较低的淡水中养成。南方鲆Paralichthyslethostigma分布于北卡州到佛罗里达州北部的大西洋沿岸以及佛罗里达州南部海湾直到德克萨斯州南部海峡沿岸。南方鲆在佛罗里达州的间断自然分布使很多生物学家认为南方鲆有两个自然分离的遗传种群。南方鲆被发现分布在36‰的盐水，半咸水，乃至淡水中，被誉为广盐种类。南方鲆的生活史中最突出的特点是变… 相似文献
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美国鲥鱼的生物学特性与集约化养殖管理 总被引：4，自引：0，他引：4
美国鲥鱼（American shad，Alosa sapidissima）是世界上个体最大、生长速度最快的一种鲥鱼。由于其形态特征、鱼肉品质和味道等都与长江鲥鱼十分相似，在长江鲥鱼濒临灭绝的情况下进入我国市场，销售价格十分可观。自2003年以来，我国每年从美国引进近千万粒受精卵，形成了养殖美国鲥鱼的热潮。尽管养殖面积和数量逐年扩大，但事故频频发生，鲥鱼养殖成功率很低，给养殖户带来了不可挽回的经济损失，挫伤了养殖积极性。通过分析国内养殖户美国鲥鱼养殖失败的教训，我们发现，很多原因是由于缺乏对鲥鱼的生物学、生理学和行为学等特性的了解。 相似文献
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Bioassays in static water (mean ± SD; temperature, 20–22 C; pH, 8.2–8.4; alkalinity, 205 ± 10 mg/L CaCO3; total hardness, 220 ± 10 mg/L CaCO3) were used to determine median lethal concentrations (LC50) of un-ionized ammonia (NH3-N) for striped bass Moronc saxatilis and hybrid striped bass M. saxatilis × M. chrysops. The 96 h LC50 for striped bass was 1.01 ± 0.24 mg/L NH3-N3 and was significantly higher than the LC50 for hybrid striped bass (0.64 ± 0.05 mg/L NH3-N). The effects of sublethal ammonia were evaluated after fish were exposed for 96 h to 0.0, 0.25, or 0.5 mg/L NH3-N or to additional exposure to oxygen depleted water (about 2.0 mg O2/L). Plasma ammonia of striped hass did not change as sublethal ammonia increased, but exposure to oxygen depletion caused a decrease in plasma ammonia. In contrast, plasma ammonia of hybrid striped bass increased as environmental ammonia increased, and increased further after exposure to oxygen depletion. Plasma cortisol levels of striped bass were significantly higher and more variable than cortisol levels of hybrid striped bass; additional exposure to oxygen depletion increased this variability, but these responses may be due to the stress of handling and confinement. Mean differences also existed between species for hemoglobin and hematocrit, while differences in variability occurred for osmolality and oxygen depletion rates. Striped bass tolerated ammonia better than hybrid striped bass but were more susceptible than hybrid striped bass to the additional stress of oxygen depletion. Most changes in physiological characteristics were relatively independent of environmental ammonia, but they were affected by oxygen depletion challenge. 相似文献
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Selenium: relation to decreased toxicity of methylmercury added to diets containing tuna 总被引：7，自引：0，他引：7
H E Ganther C Goudie M L Sunde M J Kopecky P Wagner 《Science (New York, N.Y.)》1972,175(26):1122-1124
Japanese quail given 20 parts per million of mercury as methylmercury in diets containing 17 percent (by weight) tuna survived longer than quail given this concentration of methylmercury in a corn-soya diet. Tuna has a relatively high content of selenium and tends to accumulate additional selenium when mercury is present. A content of selenium in the diet comparable to that supplied by tuna decreased methylmercury toxicity in rats. Selenium in tuna, far from being a hazard in itself, may lessen the danger to man of mercury in tuna. 相似文献
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M. S. Smith N. J. Booth W. S. Stephens C. A. Goudie B. A. Simco 《Journal of aquatic animal health》2015,27(3):152-155
The ability of the anesthetics metomidate hydrochloride and tricaine methanesulfonate (MS-222) to mitigate the cortisol stress response of Channel Catfish Ictalurus punctatus was evaluated during a 10-min confinement stress. The cortisol concentrations of Channel Catfish anesthetized in metomidate hydrochloride remained consistent throughout the 10-min exposure; however, for fish anesthetized with MS-222 and nonanesthetized fish, cortisol concentrations were approximately 7- and 22-fold higher, respectively, than the baseline concentrations. While both anesthetics reduced cortisol concentrations relative to those of nonanesthetized fish, these results suggest that MS-222 is an appropriate anesthetic to use during the initial 5 min of sedation and that metomidate hydrochloride is appropriate for longer periods of sedation.
Received November 18, 2014; accepted April 9, 2015 相似文献
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Crown shyness or canopy disengagement, the phenomenon wherein gaps around trees develop from swaying, whipping and shading, has been identified in the literature since the 1920s. Recent results by researchers at the University of Alberta have clearly described many of the processes involved for lodgepole pine [e.g. Rudnicki, M., Silins, U., Lieffers, V.J., Josi, G., 2001. Measure of simultaneous tree sways and estimation of crown interactions among a group of trees. Trees 15, 83–90; Rudnicki, M., Lieffers, V.J., Silins, U., 2003. Stand structure governs the crown collisions of lodgepole pine, Canadian Journal of Forestry Research 33, 1238–1244; Rudnicki, M., Silins, U., Lieffers, V.J., 2004. Crown cover is correlated with relative density, tree slenderness, and tree height in lodgepole pine. Forest Science 50, 356–363; Fish, H., Lieffers, V.J., Silins, U., Hall, R.J., 2006. Crown shyness in lodgepole pine stands of varying stand height, density, and site index in the upper foothills of Alberta. Canadian Journal of Forestry Research 9, 2104–2111]. However, explicit models of crown shyness are sparse in the literature. This paper describes the development of empirical models of crown shyness in lodgepole pine for British Columbia (BC). We measured crown area and neighbour locations on 60 trees growing in 13 stands in central BC. We estimated potential crown area (AV) using stem maps and Voronoi polygons constrained by estimates of maximum crown width, and then related observed crown area (AC) to AV and additional individual tree variables. One of the nine prediction equations was coded into a spatially explicit tree growth model modified to evaluate the effects of crown shyness at the stand level. Crown shyness models validated well against two independent sources and when linked with a light model tRAYci [Brunner, A., 1998. A light model for spatially explicit forest stand models. Forest Ecology and Management 107, 19–46], increased the below-canopy light by 0.07–0.11. 相似文献
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Cheryl A. Goudie Bill A. Simco Kenneth B. Davis Nick C. Parker 《Journal of the World Aquaculture Society》1992,23(2):138-145
Reproductive performance of albino and pigmented channel catfish ( Ictalurus punctarus ) females was compared when spawning was induced with HCG (human chorionic gonadotropin) or Ovaprim 3 (domperidone and [d-Ala6 , Pro9 NEt]-luteinizing hormone-releasing hormone). In 1985, only HCG was used to induce spawning. Albino females required more injections, had a longer latency period from time of first injection to spawning, and had lower spawning success (30%) than pigmented females (77%). No differences were observed between albino and pigmented females for time-of-day of spawning, number of eggs obtained by manual stripping, and number of eggs/kg body weight. In 1988, HCG, Ovaprim, and saline (control) were used to induce spawning. HCG induced spawning in 80% of albino and 71% of pigmented females. Ovaprim induced 67% of pigmented females to spawn, but only 2 of 5 albino females spawned. One of four pigmented females injected with saline spawned. Albino females yielded 40–50% fewer eggs/kg body weight than pigmented females. Other performance characteristics for albino and pigmented females were similar whether injected with HCG or Ovaprim. High temperatures encountered during the 1985 spawning season my have had a differential effect on albino and pigmented fish and may account for some differences in spawning success. 相似文献
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A laboratory experiment was used as a model to investigate interactions within a hyper-arid and hyper-saline weathering environment based on conditions observed in the Atacama Desert, northern Chile. The experimental design produced a matrix of 18 different weathering environments with six levels of salt (sodium nitrate) availability and three levels of fog precipitation. The experiment took place over an 11-week period. Over this time, 10 weekly fog applications modified the experimental conditions. From a theoretical perspective, the weekly fog applications generate an open rather than a closed system, which may be more representative of conditions in the field. The breakdown of the chalk blocks used was assessed in two ways. Firstly, qualitative observations were made at weekly intervals of the nature of morphological changes. Secondly, at the end of the experiment, breakdown was assessed by counting the number of discrete pieces greater than 1 g liberated by each block. The electrical conductivity at the base of each block was also measured. Collectively, the results indicate that fog appears to control the rate of breakdown and that salt availability controls the timing of the response. The style of breakdown was similar irrespective of the fog and salt levels. The morphological observations show the results of a sequence of events, with the blocks evolving as the experiment progresses; as such, they provide an experimental example of the role of inheritance in weathering processes. 相似文献
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