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英国斯特林大学水产养殖研究所对罗氏沼虾和日本沼虾两种幼体生长进行比较研究。通过两种沼虾幼体生长比较研究结果表明,发现日本沼虾幼体存活率高于罗氏沼虾幼体存活率20%,其日本沼虾幼体变态速度比罗氏沼虾幼体快。但日本沼虾幼体孵化数大大低于罗氏沼虾,日本沼虾幼体平均孵化数为1500尾,而罗氏沼虾幼体平均孵化数为354100尾。仔虾孵化数的严重差异,直接影响了亲虾需要量。日本沼虾 相似文献
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罗氏沼虾幼体刚从卵孵出时呈潘状,称溞状幼体。这是罗氏沼虾整个生命周期中唯一在咸淡水中度过的生活阶段。在此期间,幼体要求一定的盐度、温度、饵料和氧量等,才能完成多次蜕皮,变态成幼虾。因此,观察幼体阶段不同发育时期的形态特征,研究它的生活习性,以便提供适宜的生活环境条件,这对提高幼体质量,提高幼体培育成活率具有重大的实践意义。 相似文献
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滨海盐碱地盐度为34.89的咸井水,经沉淀、曝晒、充气、消毒。施用EDTA2~3~106络合重金属离子,再用淡水调成盐度12的半咸水,进行罗氏沼虾育苗试验。当卵子由淡黄变为浅灰时,移至半咸水中孵化,每天5:00用120目筛绢网将孵出的蚤状幼体捞入幼体培育池,布他密度8~12万尾/m3。幼体在动期前,每天投喂卤虫无节幼体2~3次,Z6期后改投蛋黄、蛋羹,口喂8次。4000尾亲虾在290m3水体中,育出虾苗571.9万尾,幼体成活率25%以上。专家鉴定认为,在同类研究中居国内领先水平。 相似文献
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2010年2月,对采自江苏吴江、广西三塘和广西南宁国家级良种场共3种不同来源的罗氏沼虾(Macrobra-chium rosenbergii)进行从幼体阶段至变态苗阶段的培育试验;干量容积法推算产苗量,计算育苗成活率。试验结果表明,3种不同来源幼体的育苗成活率分别为73.6%、65.2%和90.4%,成活率差异明显;其中,国家级广西南宁罗氏沼虾良种场的育苗成活率最高。在育苗生产中,必须注重罗氏沼虾亲本的种质复壮与培育,才能保证幼虾的质量,有利于提高其养殖成活率。 相似文献
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在罗氏沼虾育苗过程中,福尔马林是常用的消毒药物,了解福尔马林对罗氏沼虾幼体生长发育的影响是育苗生产中至关重要的问题。为此,我们进行了不同浓度的福尔马林对初孵罗氏沼虾的影响试验,旨在为生产提供一些参考依据。现将结果报告如下。 相似文献
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Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean 下载免费PDF全文
The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna. 相似文献
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In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg. 相似文献
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William King V David L. Berlinsky Craig V. Sullivan 《Fish physiology and biochemistry》1995,14(6):489-500
Plasma estradiol-17 (E2), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E2 and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E2 and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass. 相似文献
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Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide 总被引:1,自引:0,他引:1
Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response. 相似文献
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An overview of stress physiology of fish transport: changes in water quality as a function of transport duration 下载免费PDF全文
This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO2 and ions should be more often evaluated. Plasma Na+ and Cl‐ are very useful markers of acidosis, due to their respective exchange for H+ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters. 相似文献
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Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845) 下载免费PDF全文
Abalone populations have declined worldwide, generating interest in enhancement using hatchery‐reared individuals. In many cases, such restoration efforts have met with limited success due to high predator‐induced mortality rates. Furthermore, the mortality rates of outplanted hatchery abalone are often considerably higher than for wild individuals. This study uses northern abalone (Haliotis kamtschatkana) as a case study to determine whether hatchery‐reared abalone behave differently than their wild counterparts. In the field, outplanted hatchery‐reared abalone were significantly less responsive than wild abalone, in terms of number of abalone responding and intensity of response, to nearby movement and to physical contact with an inert probe. Also, when encountering a cue to which all abalone responded (a seastar predator), hatchery‐reared individuals remained subdued. Anti‐predator behavioural deficits in hatchery‐reared abalone were more pronounced in 4‐year‐old individuals than in 1‐year‐old individuals, suggesting an influence of either age or amount of time spent in the hatchery environment. These behavioural differences are expected to increase the vulnerability of hatchery‐reared abalone to predators, and are likely a major cause of their elevated predator‐induced mortality when outplanted. 相似文献
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The toxic effects of Cd2+ on Ca2+ influx kinetics in developing tilapia (Oreochromis mossambicus) larvae were evaluated. Addition of 20 µg l-1 of Cd2+ to the environment of 0 and 3 day-old larvae competitively inhibited the Ca2+ uptake within 4h resulting in a great increase in Km values for Ca2+ influx (19.3 and 17.4 fold, respectively) as compared with their respective controls. Consequently, the actual Ca2+ influx of larvae in solutions of 0.2 mM Ca2+ are suppressed by 32–45%. Also, 3 day-old larvae were more sensitive to internally accumulated Cd2+ than 0 day-old larvae. Although the Ca2+ influx in 0 and 3 day-old larvae may be restored to the levels of their respective controls with 24h of being transferred to a 20 µg l-1 Cd2+ solution, total body Ca2+ content was significantly reduced in 3 day-old larvae. Increased Ca2+ uptake efficiency ensures sufficient Ca2+ for normal growth. However, rapid increase in Ca2+ influx after hatching also leads to higher Cd2+ uptake. Exposure to Cd2+ will lead to a drop in body Ca2+ content resulting in retardation of larval growth. Therefore, we conclude that if Ca2+ uptake is interfered with at this critical stage of development, larvae will not be able to maintain normal levels of body Ca2+ and will show signs of Cd2+ poisoning. 相似文献
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Abstract– Literature evidence suggests that lake-dwelling longnose gar (Lepisosteus osseus) enter tributary streams to spawn, Until the present study, the dynamics of this breeding migration had never been investigated quantitatively. During the summers of 1991 and 1992, longnose gar were captured as they entered Weaubleau Creek, Missouri, a tributary of Harry S. Truman Reservoir. The in-stream spawning migration began in early April and ended in late May, and was positively correlated with stream flow and water level, and negatively correlated with water temperature. In-stream residence times ranged from 15 to 94 days, with males exhibiting longer residence times than females. Once in-stream, longnose gar travelled as far as 10 km upstream and occupied certain pools at greater relative frequencies. Although the reason for this preferential utilization is not completely understood, it may relate to pool depth and riffle proximity. Longnose gar disperse from the spawning stream great distances, with gar captured in Weaubleau Creek being recaptured up to 48 km away. This information should provide fisheries biologists the means to consider the reproductive ecology of this species in their conservation and management decisions. 相似文献
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D.R. Tocher M. Agaba N. Hastings J.G. Bell J.R. Dick A.J. Teale 《Fish physiology and biochemistry》2001,24(4):309-320
The desaturation and elongation of [1-14C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental
diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high
oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy
the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition
was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte
fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed
that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the
VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase
activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities
in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but
primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional
data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of
EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that
manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important
consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the
subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular
biological and genetic level.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Production of diatom–bacteria biofilm isolated from Seriola lalandi cultures for aquaculture application 下载免费PDF全文
Controlled incorporation of selected microalgae and bacteria in aquaculture systems can be beneficial because they can act as microbiological control. That is why the characteristics of biofilm generated naturally in Seriola lalandi culture cages were analysed, their potential benefit to the growth of larvae was studied, and their controlled use for improving the larval viability and as a vector to improve incorporation of previously studied probiotic bacteria was tested. According to biodiversity results, these biofilms are composed of a diatom–bacteria mix showing a decrease in biodiversity in laboratory culture conditions being dominated by Navicula phyllepta and bacteria of the family Rhodobacteraceae. This can be produced on mesh substrates incorporated in bioreactors with rapid growth rate and adhesiveness. Preliminary results from the addition of substrates with this specific biofilm in larvae culture systems showed that it is consumed by the larvae without negative effects, while positive effects on the viability of larvae in combination with probiotics were observed. Considering preliminary results, the addition of these specific substrates with diatom–bacteria biofilms could be a good improvement for aquaculture systems and together with the use of probiotics can contribute to maintaining a stable and controlled system improving the viability of the larval fish culture in its early stages. 相似文献