池塘套放小体积网箱培育鱼种技术

本试验总结了在池塘中套放小体积网箱培育大规格鱼种的技术。2000年的试验示范表明，经过6～7个月左右的饲养，共收获大规格鱼种62180尾，其中鲤鱼种43610尾，成活率82．6％，草鱼种18570尾，成活率59．5％；平均饵料系数1．71，共获利2．4万元，投入产出比1：1．89。这种箱池式模式大大提高了池塘养殖的综合效益。     

第一讲 鱼苗的培育

鱼苗、鱼种,是食用鱼养殖的物质基础。苗种培育,对整个养鱼生产有根本性的影响。主要养殖鱼类的苗种培育,一般分鱼苗和鱼种两个阶段,即:将孵化后数天的鱼苗,经15～20余天养成1寸左右的夏花;将夏花经3～5个月养成3～5寸以上的当年鱼种。对草、青鱼鱼种,也可再经1～2年培育成体重0.5～1.5斤的2～3龄鱼种,以养     

大眼狮鲈的池塘养殖技术研究

1993年和1994年哈尔滨市水产研究所二次从加拿大移植大眼狮鲈发眼鱼卵，经室内孵化培育出鱼苗，在池塘中进行鱼苗、鱼种、成鱼养殖。鱼苗培育35天，体长平均达5．2cm，成活率分别是75．8％和17．9％，鱼种培育套养方式成功，亩套养100－150尾，经3个月的养殖，体重可达50－100克，成鱼养殖，亩套养20－40尾，经5个月的培育体重可达300－475克，2龄鱼体重达670－1020克，单产5－10千克。     

长吻鮠养殖技术讲座（四） 第四讲 鱼种培育

长吻鮠养殖技术讲座（四）第四讲鱼钟培育鱼种培育是指把寸片（３．３ｃｍ）鱼苗培育４～５个月使之达到全长１２～２０ｃｍ、尾重４０～１００ｇ这样大规格鱼种的饲养过程。长吻鲍鱼种培育的关键技术．一是转食驯化，二是鱼种所需的配合饲料。１．转食驯化转食驯化宜在几...     

王家福网箱养鱼好经验

一、搞好网箱配套。王家福告诉笔者,用池塘培育的鱼种进行网箱养殖成鱼,半个月内鱼种很不适应,在网箱内东冲西撞,伤亡很大,加上运输中的损伤,成活率不到80%。而网箱培育的鱼种已适应了网箱内的水环境,极少死亡。他的网箱有4种网眼规格,进行系列化配套生产。利用5号、8号网制成的网箱培育鱼种;10号网、14号网制成的网箱养殖成鱼。买进夏花先进5号网进行培育,2～3个     

人工饲料培育翘嘴红鲌冬片鱼种

为开发翘嘴红的人工养殖，我们在２０００年６月突破了池塘小水体条件下培育翘嘴红亲鱼的人工繁殖，同年便相继进行翘嘴红的夏花鱼种培育试验和翘嘴红冬片鱼种人工饲料驯化培育试验，均获得成功。现将两年来翘嘴红冬片鱼种人工饲料驯化培育的试验情况总结如下。一、材料和方法１．夏花鱼种来源试验所用的翘嘴红夏花鱼种，均由人工繁殖的鱼苗培育而成，规格３～５厘米／尾，体质健壮，活力强。２．池塘条件冬片鱼种培育试验的池塘有两种：一是普通的养鱼池塘，面积２～４亩，水深１．２～１．４米；另一种是虾蟹养殖池塘，面积０．８～９亩，…     

长吻旎网箱养殖试验

2005年网箱培育长吻能冬片鱼种，应用5m×5m×3．5m的网箱，放养规格为3～4cm／尾的长吻鲍夏花鱼种，放养密度56～790尾／m^2，投喂粗蛋白为42％～46％的配合饲料，经7个月养殖，长吻鲍鱼种平均规格达165g／尾，成活率82．5％，单产9kg／m^2，饲料系数1．26，投入产出比1：2．04；2006年网箱养殖长吻脆商品鱼，应用5m×5m×4．5m的网箱，放养规格为133g／尾左右的长吻能冬片鱼种，放养密度32～50尾／m^2，投喂粗蛋白为42％～43％的配合饲料，经6个半月时间的养殖期，养成个体规格在0．5kg／尾以上的长吻娩商品鱼比例达86％以上，成活率82．6％～87．0％，饲料系数1．38，单产22．83～26．24kg／m^2，投入产出比1：1．59。     

自制小网箱培育草鱼种效果好

目前，渔具厂生产的成品鱼种网箱的网目一般为1．5cm，要求进箱鱼种规格达6．7cm左右。多数养鱼户都是利用池塘或稻田发花，再进鱼种网箱中养殖，这样鱼种进箱时间约在六月底至七月初。由于各种原因，许多养鱼户很难在二个月内将草鱼海花培育到6．7cm，     

两级网箱培育大规格鱼种试验

1993年5～6月在罗城县龙潭水库用两批各4个网箱进行了两级草鱼种培育试验。第一阶段鱼种从3．5～5cm培育到8～10cm，第二阶段从8～10cm培养到16～20cm的大规格鱼种。试验取得了较好的效果：投放鱼种20000尾，在两个月时间内，平均产鱼种112尾／m^2，共产16-20cm鱼种12545尾，成活率62．73％，产值6272．25元，扣除成本4017元，得纯利润2255．50元，投入产出比1：1．56，利润率56．17％，每个网箱平均获利563．87元。     

池塘培育大规格草鱼鱼种技术

草鱼是淡水养殖的优良品种，但由于草鱼鱼种培育成活率低等原因，近几年养殖数量下降于其它品种。笔者为探索大规格草鱼鱼种培育高产技术，在本市淡水养殖试验场进行了试验。1997年养殖试验面积26亩，总产15990kg，亩产615kg，亩净产大规格草鱼鱼种410kg（4510尾），养殖成活率达88％。总结几年来的养殖经验，必须做好以下几方面的工作：一、池塘条件及放养前的准备工作1．池塘的基本条件：面积2～5亩，水深1．5～22m，排、灌水方便，池底平坦，并有10cm左右的淤泥，有利于保水保肥和拉网操作。2池塘的情整、消毒：鱼种下塘前，一定要做好池…     

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.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

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.