加州鲈商品鱼网箱养殖技术

加州鲈又名大口黑鲈,是一种名贵淡水鱼类,具有适应性广、生长快、病害少、肉味美、营养丰富、商品价值高、养殖效益好等特点。现将加州鲈商品鱼网箱养殖技术介绍如下: 一、网箱规格 加州鲈商品鱼养殖网箱一般采用2×3或3×3聚乙烯线编织而成,为便于操作其设计规格为4m×5m×2m或4m×7m×2m,入水深1.5m。网目大小视鱼种放养规格     

史氏鲟网箱养殖技术

近年来,全国各地均开展了鲟鱼人工养殖,但由于养殖鲟鱼的时间短,在养殖技术及疾病防治方面技术不甚完善,笔者就这几年史氏鲟网箱养殖的经验作一总结。一、网箱设置地点网箱设置在水面开阔、水质清新、无污染的地方,一般要求水深4m以上,水深最好在6m~8m,如果水位过浅则不利于网箱内外的水体交换,使水质恶化而影响鱼体生长,甚至造成缺氧死鱼。网箱一般设置在流速0.2m/s～0.3m/s的水域。网箱在鱼种放养前宜提早入水设置,待网片着生藻类等附着物后再放养鱼种,以免擦伤鱼体。二、网箱结构和安装网箱规格不易过大,一般为3m×3m×3m、4m×4m×3m或5…     

鲈鱼水库网箱养殖技术

鲈又名花鲈、寨花、鲈板,是一种凶猛肉食性底层鱼类,它具有肉鲜味美、生长速度快等特点。鲈较耐低温,其适宜水温为3—29℃,最适生长水温为16～17℃,水温在3℃以下停止生长。鲈属于广盐性鱼类,在海水和淡水中均可正常生长。 一、养殖水域和网箱的制作 网箱养殖要选择在没有工业污染,水质良好,各种理化因子比较稳定的较大型水库。网箱用聚乙烯网片做成,规格为4 m×4 m×3 m。网目大小1～2 cm,单层网衣,网架用木杆做成,浮力采用泡膜浮子,网箱上面加盖,以防鱼逃逸。网箱要设置在水库比较深的部位。     

全雄太阳鲈网箱养殖技术的研究

2 0 0 1年设置 2m× 2m× 2 5m网箱 6只 ,其中 3只放养密度为 4 0 0尾 /m3 ,鱼种规格 2 2cm ;另 3只放养密度为 5 0 0尾 /m3 ,鱼种规格 2 7cm ,试验期 180d。 2 0 0 2年设置 2m× 3m× 3m网箱 6只 ,3只一组。一组放养密度为 375尾 /m3 ,鱼种规格 4 0cm ;另一组放养密度为 4 17尾 /m3 ,鱼种规格 6 5cm ,饲养期16 0d。 2 0 0 1年成鱼起捕平均规格为 0 17kg/尾 ,单位产量 6 2 6kg/m3 ,成活率 80 9% ,单位箱体纯收入996 6 7元 /m3 。 2 0 0 2年成鱼起捕平均规格为 0 2 4kg/尾 ,单位产量 87 1kg/m3 ,成活率 90 7% ,单位箱体纯收入 10 90 6元 /m3 。试验证明 :全雄太阳鲈适合高密度的网箱养殖。     

丹江口水库网箱养殖史氏鲟试验

在丹江口水库进行了1周年的网箱养殖史氏鲟试验,分析了丹江口水库的水域条件、苗种规格及养殖管理。研究了网箱的设置、规格、深度、水温与养殖品种的关系。结果表明:丹江口水库适合史氏鲟网箱养殖,网箱规格4m×5m×3m为佳,苗种规格以25～50g为宜。     

水库网箱养殖花(鱼骨)鱼技术

花鱼骨 (Hemibarsmaculatesbleeker)隶属于鲤科 ,鱼句亚科 ,鱼骨属 ,俗称“芝麻鱼”“冷丁”。花鱼骨属杂食性、底层鱼类 ,起捕比较困难 ,而水库网箱养殖花鱼骨 ,不但解决起捕难问题 ,也适时供应市场 ,丰富人们的食膳 ,为养殖户创造了较高的效益。为了扩大花鱼骨生产 ,在水库中推广网箱养殖花鱼骨鱼技术 ,2 0 0 4年我站在广丰县军潭水库进行网箱养殖花鱼骨鱼的试验示范。该技术示范 ,共设置网箱 1 0 0个 ,每个网箱规格为 3m× 5m× 1 .6m ,分二排且分别呈“一”字排列。本示范鱼种放养于 4月初开始 ,鱼种平均尾重 40— 50g ,每箱放养量为45…     

不同网箱饲养条件下湘云鲫生长的研究

在 6m× 4m× 2 5m、 2m× 2m× 2 5m的两组 6口网箱中按 195尾 /m2 、 15 0尾 /m2 、 115 /尾m2 三种密度投放湘云鲫 ,大、小网箱分别投喂含粗蛋白质为 35 2 %和 30 0 %的两种饲养。两个月的养殖试验表明 :大网箱的高、中、低密度养殖的平均增重倍数分别是 0 5 8、 0 81、 0 6 3,饲料平均转化效率分别是 4 4 %、 4 7%、4 3% ;小网箱的高、中、低密度养殖组的平均增重倍数分别是 0 2 5、 0 4 1、 0 34,饲料平均转化效率分别是4 3%、 4 4 %、 4 2 %。对比试验表明用粗蛋白质含量为 35 2 %的饲料投喂 ,密度为 15 0尾 /m2 左右的大网箱养殖效果最好     

河道网箱养殖建鲤高产技术

淡水网箱养鱼一般是在水库中进行,河道网箱养鱼尚不多见。2002年郯城县渔业技术推广站在境内白马河上选择宽阔河道投放了4只网箱,进行网箱养殖建鲤高产技术试验。现将试验情况报告如下:1 材料与方法1.1 网箱设置 使用6m×6m×2.6m的网箱4只,选     

网箱养青虾周期短 见效快

青虾的网箱养殖周期短、产量高、收效快。现将此项新技术介绍如下：一、养殖水域的选择宜选用微流水体，水质清新，透明度高（不低于40cm），pH值7左右，溶氧4．8mg／L以上，水质不受污染的河道、水库、湖泊等均可。二、网箱设置网箱用聚乙烯网片缝制，网目为24－25目／cm2，网质要好，网线要紧，以防水鼠等咬破而使青虾逃跑。网箱规格以3m×3m×2m－5m×5m×2m为宜，可选用锚、石、桩、缆等任一种方式固定网箱，箱底四角设置沉子，使网箱上下充分张开放四方体，并固定其形状。网箱的排列方式与布局不限，但箱距不小于‘m，以防止网箱！司…     

常规鱼类养殖技术之三:小浪底水库网箱养殖花鲢技术

小浪底水库位于黄河中游最后一段峡谷出口处,水库蓄水后,库区的土地、植被及建筑物的残壁被水淹没,会使水体肥力上升,有利于浮游生物的生长和繁殖,给发展不投饵网箱养殖提供了良好的条件。河南省济源市位于小浪底水库北岸,有3个乡镇紧邻库区,沿大坝向上距离达50km,背风向阳,库汊丰富,是养殖花鲢的理想场所。为了充分调动库区群众开展网箱养殖花鲢的积极性,市水产局在大峪镇、邵原镇等地进行了养殖试验,并取得了成功且已推广,现将网箱养殖花鲢技术总结如下,仅供参考。一、网箱结构网箱选用4m×6m×2m的聚乙烯材料组成单层封闭网身,框架用毛竹…     

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.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

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.