斑点叉尾鮰苗种培育试验报告

1987年我们从湖北省引进斑点叉尾鲴试养，经精心培育成亲鱼，于1990年获得人工繁殖成功，1991年继续进行人工繁育技术试验。两年共培育鱼苗37．8万尾，现将苗种培育试验报告如下。     

淡水池塘80:20养殖斑点叉尾(鱼回)鱼苗至鱼种试验

为了探索斑点叉尾鱼回无公害健康养殖模式,提高鱼回鱼养殖技术,促进峡江县鱼回鱼产业化发展,我们于2 0 0 4年在江西省峡江县鱼种场利用美国大豆协会80 :2 0池塘养殖模式和全植物性蛋白豆粕型膨化浮性饲料进行了斑点叉尾鱼回夏花养至鱼种的示范试验,取得了良好的试验效果。三口试验池塘中斑点叉尾鱼回经过10 9d饲养后平均体重从1.0 7g长到38.81g。鱼的总产量为16 15 .4kg ,平均成活率为86 .8%。三口池塘饲料的平均系数为0 .96 ,净收入为16 46 .0 5元/亩,投资回报率平均为6 2 .3%。试验结果表明,设计合理的养殖模式,采用优质饲料,是实现健康养殖,获得良好经济效益的关键。     

斑点叉尾鮰人工繁殖的几项要点

目前我国斑点叉尾鮰人工繁殖生产整体水平不高,苗种生产量一直上不去,据不完全统计,近几年全国斑点叉尾鮰苗种年生产量约在1000～2000万尾左右,造成苗种供求矛盾突出,影响了该鱼的推广养殖。笔者几年来通过对斑点叉尾鮰繁殖技术研究和生产实践,积累了一些技术经验,并每年生产近100万尾苗种供应各地养殖,出苗率由1990年25％提高到1993年的91％。现将斑点叉尾鮰人工繁殖的几个关键技术问题归纳一下,以供参考。 一、亲鱼培育 斑点叉尾鮰人工繁殖,生产上主要采用在原塘或产卵池放置产卵巢自然受精后收集卵块在孵化器进行人工孵化的方法。亲鱼培育是斑点叉尾鮰人工繁殖的     

斑点叉尾鮰亲鱼培育技术要点

斑点叉尾鱼回原产于美国，是美国及非洲、欧洲等国家和地区的主要淡水养殖品种和食用经济鱼类。具有适温广、易饲养、食性杂、生长快、易捕捞等特点。受到广大养殖户普遍欢迎。我们合肥市水产技术推广中心站自１９９７年引进该鱼以来，经过几年人工繁殖试验，喜获成功，现将亲鱼培育时应注意几个问题小结如下。１亲鱼选择斑点叉尾鱼回亲鱼要求个体大、体型好、无伤无病，基因来源要求较好，这样亲鱼易驯化，也易养殖和培育。体重以１．５～５千克为好，年龄要求在３冬龄以上。２亲鱼池准备选择无渗漏、底泥浅、面积０．３３～０．６７公顷，…     

斑点叉尾鱼回大规格鱼种培育技术

使用面积2668m2的池塘进行斑点叉尾鱼回大规格鱼种培育试验,通过合理投喂、采取有效的水质调控和疾病控制,结果共收获斑点叉尾鱼回大规格鱼种1090.6kg,平均规格41.5g/尾,成活率为87.6%,平均每667m2利润为1680.5元。     

美国筛选出优质斑点叉尾鮰新品系

密西西比大学水产养殖中心的科研人员将筛选出来的斑点叉尾鱼回ＵＳＤＡ 10 3品系与当地品系的斑点叉尾鱼回进行了生长、饲料效率、鱼片产量以及肉质比较。所用饲料的蛋白质含量分别为 2 6%、2 8%和 3 2 %。试验鱼规格为 3 2 .5ｇ/尾和 47.3 ｇ/尾 ,分别放养到 2 4个 0 .0 4ｈｍ2 的土池中 ,密度 185 3 0尾 /ｈｍ2 。每天进行饱食投喂 1次 ,养殖 5～ 10个月。测定结果摄食这 3种饲料的ＵＳＤＡ10 3品系的斑点叉尾鱼回 ,其增重率和饲料利用率均高于密西西比品系的斑点叉尾鱼回。组织分析测出 ,ＵＳＤＡ10 3斑点叉尾鱼回内脏的脂肪含量低、鱼…     

沿黄低洼盐碱地池塘养殖斑点叉尾鮰技术

斑点叉尾鱼回(Ictalurus punctatus)又称沟鲶,原产于美国密西西比河,是目前美国饲养规模最大的淡水鱼类,也是当前我国水产养殖中的一个优良新品种。河南省商丘鱼类良种场在虞城县北部的沿黄低洼盐碱地池塘中进行了斑点叉尾鱼回养殖试验,并获得成功,为沿黄低洼盐碱地池塘推广养殖斑点叉尾鱼回起到了示范作用。一、池塘条件用于养殖斑点叉尾鱼回的池塘位于黄河故堤南侧的低洼盐碱地上,为1998年开挖的土池,每个池塘面积约为6亩,东西走向,深2.5m,池底平坦、无淤泥,池塘保水、保肥性能好,进排水方便,且每个池塘配备有增氧机1台。养殖水源为农业…     

蓄水塘养殖斑点叉尾鱼回成鱼试验

长江水产研究所试验场用于人工繁殖的蓄水塘,面积8亩.每年6月份以前用于鲤、鲫及四大家鱼的人工繁殖蓄水,2001年我们在人工繁殖过后,利用该池进行了斑点叉尾鱼回成鱼养殖试验,取得了明显的经济效益.现将其主要措施总结如下.     

池塘培育斑点叉尾鮰苗种技术

斑点叉尾 鱼回 亦称沟鲶 ,属鲶形目 鱼回 科鱼类 ,是美国主要淡水养殖鱼类 ;该鱼具有适应范围广、食性杂、个体大、生长快 ,抗病能力强 ,肉质细嫩鲜美等优点。为了提高该鱼在北方池塘养殖产量 ,我们 1998年做了斑点叉尾鱼回 池塘苗种培育试验。1　材料与方法1 1　池塘条件本实验选在吉林农大水库渔场池塘 ;池塘面积 2 0亩 (斑点叉尾 鱼回 苗种培育池面积过大 ,不利于驯化饲养 ) ,养殖期间平均水深 1 5ｍ左右 ,池塘底泥在 2 0～ 30ｃｍ之间 ,注排水方便 ,水量充足 ,水质良好。 6月 18日全池用生石灰 2 6 0ｋｇ遍洒 ,6月 2 0日用网拉池底 …     

斑点叉尾“传染性套肠症”的诊治

斑点叉尾鱼回“传染性套肠症”是近年来在我国发生的一种斑点叉尾鱼回的新型细菌性传染病,危害很大,已经连续几年造成了大批的斑点叉尾鱼回发病死亡,严重地威胁着斑点叉尾鱼回养殖业的健康发展。目前初步认为该病是由嗜麦芽寡养单胞菌(Stenotrophomonasmaltophilia)引起的斑点叉尾鱼回的急性致死性传染病,以发生严重的肠炎、肠套叠和脱肛为特征,在短时间内即可引起大批的斑点叉尾死亡,我们称此病为“斑点鱼回叉尾鱼回传染性套肠症(InfectiousintussusceptionofchannelcatfishIICC)”。由于该病具发病突然,来势凶猛,传染快,呈流行性,死亡…     

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.