成鱼池套养鳜鱼的技巧

成鱼池内套养鳜鱼,能有效清除池内野杂鱼类,避免野杂鱼与主养鱼类争饵料、争溶氧、争空间;同时还能清除池内体质弱、规格小的劣质鱼种。笔者结合生产实践,总结了以下套养技巧,现介绍如下。一、以草食性鱼为主养鱼类的成鱼池更适合套养鳜鱼草鱼、鲂鱼等草食性鱼类与鳜鱼一样,喜生活于水质清新、溶氧丰富的水域环境中,同时用于投喂的水草大多从湖泊、河道等自然水域中捞取,水草内附有大量的野杂鱼幼鱼与鱼卵等,为鳜鱼生长提供了丰富的饵料来源。另外在采用注换水、增氧等水质调控的措施时,这些鱼类的要求基本一致,管理上较为方便。二、套养的…     

河道网箱养鳜试验

近年来，山东省临沂市为打造生态水城先后兴建了小埠东、桃源、刘道口等10余座橡胶拦河坝，形成宜渔水面数万公顷，良好的自然水域条件促进了野生小杂鱼资源的大量繁殖，数量充足的野杂鱼不仅给鳜养殖提供了丰富的适口饵料，同时也大大降低了饵料鱼的运输、捕捞成本，为网箱养鳜提供了有利的条件。     

三级网箱培育乌鳢鱼种技术

丹东地区淡水饵料鱼资源比较贫乏，而海水小型杂鱼资源比较丰富，多数水产冷冻加工厂均有加工和冷藏，可做为淡水肉食性鱼类的饵料鱼。2003年6月，丹东市宏远水产养殖公司在凤城市土门子水库采用三级网箱，以海水小杂鱼“沙里钻”为饵料鱼，进行网箱培育乌鳢鱼种技术研究获得成功，现报告如下。     

大水域网箱养殖湘云鲫成鱼高产试验

正济宁市任城区地处南四湖北岸,此处湖泊属"草型湖泊",资源丰富,濒临任城的湖泊面积2万余亩,相对封闭的水域有0.6万亩。沿岸带和亚沿岸带水域内浮游植物、着生藻类、水生维管束植物丰富,组成了复杂的生物链,为鱼、虾、蟹、贝提供了良好的饵料。水域生产力高,水质良好,发展水产养殖业前景广阔。任城区水产局立足实际,在不破坏当地生态系统的前提下,利用这些宜渔资源,开展了大水域     

饵料鱼的简易利用方法

许多肉食性及偏肉食性的养殖鱼类，在野生条件下以其它杂鱼为食，人工养殖时仍然保留着摄食饵料鱼及饵料酋制品的特别偏好，灵活利用饵料鱼是饲养这些肉食性或偏肉食性鱼类的理想方法，也是解决其动物性饵料问题的重要途径。饵料鱼的选择利用多以成本低廉、养殖有利为原则，可选作饵料鱼的对象有：①野杂鱼，野来鱼在养殖水体中与养殖鱼类争夺饵料与溶氧，可通过拉网或诱捕等方法捕获，饲喂肉食性鱼类，这是一种变害为利的利用方法。②养殖鱼类自行繁殖的鱼苗，如罗非鱼等，在养殖时大量繁殖，难以控制，对成鱼养殖不利，可将鱼苗捕获，饲喂…     

基于生态系统服务价值的博斯腾湖小湖湿地生态需水核算

湖泊湿地生态系统是陆地生态系统的重要组成部分，适宜的水文条件保障着湖泊湿地生态系统的健康。本文以博斯腾湖小湖湿地为例，依据能值理论系统地计算湖泊湿地各项生态系统服务价值量，并运用相关分析、层次聚类分析等方法结合生态系统服务计算结果与四项关键水文参数，综合确定研究区适宜的生态需水范围。研究结果表明，博斯腾湖小湖湿地生态系统服务价值总量由2013年以前的上下波动（平均年增幅-0.2%，其中有7年为负增长）转变为2013年后的持续增加状态（连续6年增加，平均年增幅6%）；区域来水量则经历了2000-2003年的丰水期、2005-2013年的枯水期以及2013年以来的水量持续增加等三个阶段；生态需水核算结果建议博斯腾湖小湖湿地应保证一年之内日均流量低于8.3 m^3/s的天数不超过72天，而一年之中日均流量超过20.8 m^3/s的天数不低于80天，湿地生态需水量在8.0-8.7 10^8m^3/a之间，最适宜生态水位范围为1047.4-1047.6m。本研究利用生态系统服务价值核算了湖泊湿地生态需水，对区域水资源调控提供了积极的参考价值。     

黄河入海口海域浮游植物丰度及其多样性研究

黄河人海口水域是黄河人海的通道，也是许多江海鱼类的洄游通道、产卵场和索饵场。黄河入海口水域水文环境复杂多变，近年来由于受人类活动和陆源污染物排放等因素的影响，水质逐渐趋于富营养化。浮游植物是海洋生态系统中初级生产者，又是海洋动物直接或间接的饵料，因此浮游植物的群落结构是反映水域生态环境好坏的重要指标之一。     

貝加尔雅罗鱼

名称:贝加尔雅罗鱼学名:Leuciscus baialensis(Dyb.) 鲤形目鲤科雅罗鱼属地方名:小白条、小白鱼分布:雅罗鱼属是栖息于欧溯、亚洲西部和北部及美洲水域中的江河和湖泊鱼类。贝加尔雅罗鱼在苏联从鄂毕河到科雷马河的西伯利亚地区较多见;在我国则系新疆北部额尔齐斯河、乌伦古河的主要经济鱼类。1968年秋至1969年秋移植至新疆南部的博斯腾湖。现已成为该湖的主要经济鱼类之一。     

湖泊围网养殖鳜鱼技术

鳜鱼为肉食性凶猛鱼类,终生以活鱼为饵料,喜水质清新的微流水域,常潜伏于湖泊浅水区的水底石穴或草丛中。在湖泊围网中养殖鳜鱼有很大的优越性。湖泊不仅水质条件好,溶氧量高,而且有着非常丰富的野杂鱼资源。因此,围网养殖鳜鱼,无需套养饵料鱼,只要在围网周围设几道簖,每天将     

湖泊围网养殖鳜鱼技术

湖泊围网养殖鳜鱼技术湖泊水质条件好，围网养殖鳜鱼无需套养饵料鱼，只要在同周围设几道簖，每天将捕获的小野杂鱼投入围同作活饵料即可。１、围网水域的选择选择水深１．５—３ｍ湖底平，水草茂盛，水流平缓，水质清新，无污染的水域。２、围网的设置图网养殖鳜鱼的面积...     

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.