不同密度鳜池套养罗氏沼虾效果对比试验

正近年来,随着鳜养殖的深入,苗种放养密度逐步加大,病害日趋严重,养殖风险逐步增高,已成为鳜养殖业健康发展的瓶颈~([1]);罗氏沼虾养殖效益虽然稳定,但主养模式水体富营养化问题限制了其进一步发展~([2])。鳜池套养罗氏沼虾作为一种新的健康混套养模式应运而生,该模式利用鳜和罗氏沼虾的不同生物学习性,在鳜池塘中套养罗氏沼虾,充分利用水体空间,增加单位养殖水体的经济效益~([2]),同时实现鳜养殖废弃物的循环利用,净化养殖水体环境~([3]),减少鳜病害发生,降低鳜的养殖风险,提高水产品质量。但目前还未进行该模式下鳜放养密度对罗氏沼虾成活率及套养效果的影响的研究。该试验旨在通过对比试验研究池塘中不同鳜放养密度对罗氏沼虾套养效果的影响,探索鳜最佳的放养密度,为鳜池套养罗氏沼虾模式标准化和扩大推广提供一些理论基础和科学依据。     

水产动物免疫增强剂的研究现状及应用前景

水产养殖业在世界范围内蓬勃发展的同时，由于高密度集约化养殖、过量投饵等原因，而造成环境恶化，导致各类细菌病、病毒病的频繁发生，严重阻碍了水产养殖业的持续健康发展。鱼类、贝类、虾类、蟹类均发生过大面积死亡，尤其某些病毒性疾病的死亡率可达60％-100％，对水产养殖业的打击是毁灭性的。目前已从生理、病理、种质、营养、生态、流行特点等方面进行了大量研究，以使用抗生素为代表的传统治疗方法，因其易导致养殖动物产生抗药性、易有残留等原因，在各国逐渐被禁用和取代。免疫机制的研究是合理有效防治各类病害的根本和依据，近来免疫学研究已成为水产动物病害研究的热点之一。     

鳜养殖概况及摄食调控机制研究进展

鳜是我国名贵的淡水经济鱼类,2019年其养殖产量已达33万t。本文从养殖现状、养殖模式及良种选育等方面介绍鳜的养殖概况。同时,鳜摄食习性独特,终生以活鱼为食。养殖生产中,主要以活饵料鱼直接饲喂,这种以鱼养鱼的方式不仅资源利用率低,对环境和资源的破坏也极大。据此,本文从环境因素和饵料性质等方面概述了影响鳜摄食的外在因素,并从摄食感觉器官和摄食调控因子剖析鳜摄食特性的内在因素,这有助于通过人工干预的方式调整鳜的摄食习性,为其转食配合饲料提供必要的支撑。此外,需加强鳜摄食调控机制及营养生理需求特性的研究,实现鳜配合饲料的突破,促进其养殖业的绿色健康发展。     

网箱培育大规格鳜鱼种技术

鳜肉质细嫩，味道鲜美，深受广大消费者的青睐，市场价格稳定，是目前淡水养殖业较为理想的养殖品种之一。鳜终生以活鱼虾为食，性凶猛。受其摄食习性的制约，在活饵料鱼缺乏地区，推广鳜主养模式有一定的困难。而发展成鱼养殖池塘套养鳜的模式却较为可行，是目前池塘增收增效的理想方法。2002年和2003年，我     

条件反射法驯化鸭绿江斑鳜食性试验

正斑鳜为鸭绿江流域优质品种,其肉质细嫩,味道鲜美,深受广大消费者青睐。目前虽然鸭绿江斑鳜集约化养殖已获得初步成功,但在养殖过程中全部投喂活饵料鱼不但增加养殖成本,而且活饵料鱼的供应受季节、营养、价格等因素制约,限制了鸭绿江斑鳜养殖业的发展,如何让鸭绿江斑鳜摄食人工配合饲料成为急需解决的问题。为此我们采用条件反射法对体长为3厘米的鸭绿江斑鳜进行食性驯化试验。     

鳜常见病害的诊断与防治技术

鳜，又名翘嘴鳜、季花鱼、桂鱼等，属鲈形目、脂科、鳜属，以其肉质细嫩、味道鲜美而深受消费者的欢迎。随着鳜养殖生产的不断发展，其病害发生也日益加剧，危害性不断增加，给养殖户造成巨大的经济损失。鳜养殖疾病的防治必须遵循“无病先防、有病早治、防重于治”的原则。笔者在长期生产实践中总结了一些鳜养殖常见病害的诊断与防治技术，供各位同仁交流参考。     

翘嘴鳜“华康1号”

正鳜鱼又名桂花鱼、季花鱼等,是淡水鱼类中的名贵鱼类,肉质纯白细嫩,味道鲜美可口。鳜鱼在我国养殖已有三十几年历史,养殖主要品种有大眼鳜、翘嘴鳜、斑鳜等,其中以翘嘴鳜养殖最为普遍,养殖效果最好。近年,鳜鱼养殖业面临的主要问题是养殖水源污染严重以及病害频发。在广东地区,自从1993年以来,每年5~10月都有鳜鱼疾病流行;其中1996~1998年间爆发鳜鱼传染性脾肾坏死病毒病,给养殖业带来了巨大的经济损失,严重阻碍了鳜鱼养殖业的正常发     

巢式PCR检测鳜传染性脾肾坏死病毒(ISKNV)

鳜(Siniperca chuatsi)传染性脾肾坏死病毒(infectious spleen and kidney necrosis virus,ISKNV)是鳜暴发性传染病的主要病原,给鳜养殖业造成了严重的经济损失,因此快速、灵敏的检测方法对鳜养殖业的发展具有非常重要的意义.根据鳜ISKNV主要衣壳蛋白(MCP)基因序列设计了2对引物,利用巢式PCR方法对病鱼脾肾组织进行扩增,建立了ISKNV快速特异的巢式PCR检测方法.应用该方法对含MCP基因的质粒进行倍比稀释后检测扩增的灵敏度可达到5 fg;巢式PCR检测的灵敏度是一步法PCR的104倍以上.     

鳜鱼人工杂交与苗种培育技术研究

翘嘴鳜与斑鳜同属鲈形目、鲻科、鳜亚科、鳜属鱼类,广泛分布于我国内陆水域,为淡水名贵鱼类,肉味鲜美,营养价值高,深受广大消费者喜爱。20世纪90年代以来,翘嘴鳜养殖蓬勃兴起,尤其在广东、江苏、浙江等地区广泛开展人工养殖,但随着养殖规模日益扩大、养殖密度不断提高以及养殖水域环境日趋恶化,导致翘嘴鳜暴发性疾病流行,给翘嘴鳜养殖生产造成巨大的经济损失,严重阻碍了其养殖业     

金融危机下，江山市鳜鱼凸显强劲市场竞争力

2008年掀起的金融危机至今未能影响浙江省江山市的鳜鱼销售，其销售量价不降反升。自2008年12月至2009年2月底，江山市已销售斑鳜20多吨（同比增加170％），翘嘴鳜80多吨（同比增加120％）；斑鳜市场价与去年基本持平，翘嘴鳜市场价同比增加18％。鳜鱼养殖成为了江山水产养殖业的翘楚。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

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.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

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.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

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.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

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.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

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.     

Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845)

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.     

Effects of cadmium on the kinetics of calcium uptake in developing tilapia larvae, Oreochromis mossambicus

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 K_m 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.     

Migratory dynamics of stream-spawning longnose gar (Lepisosteus osseus)

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.     

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

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.     

Production of diatom–bacteria biofilm isolated from Seriola lalandi cultures for aquaculture application

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.