Oxygen consumption and ammonia excretion of common wolffish Anarhichas lupus Linnaeus 1758 in an experimental-scale, seawater, land-based culture system

The oxygen consumption (0₂) and ammonia excretion (N) of juvenile and adult common wolffish was measured in culture tanks in the laboratory. The oxygen consumption and ammonia excretion were affected by temperature (C), fish size and feeding rate. For juveniles (0.5 kg; 7C) the diel oxygen consumption rate varied between 37 and 62 mg O₂ kg^-1 h^-1 and ammonia excretion between 2.3 and 5.7 mg N kg^-1 h^-1. The corresponding rates for adult fish (6.9 kg; 7C) were 29-44 mg O₂ kg^-1 h^-1 and 1.2–3.1 mg N kg^-1 h^-1. The weight-specific oxygen consumption (mg O₂ kg^-1 h^-1) was described by the following formulae: O₂ (7C) = 0.17* W^0.83 and O₂ (12C) = 0.39 * W^0.73 and the corresponding ammonia excretion (mg N kg^-1 h^-1) by: N(7C) = 0.024 W^0.75 and N(12C) = 0.073 W^0.60, where W is fish weight in g.     

渔船密闭舱室内氨气泄漏数值模拟

渔业船舶舱室内一旦氨气发生泄漏扩散,就会引起严重的环境污染和人员伤亡,为此设置了用以检测氨气泄漏的探测装置。由于安装好的探测装置不易挪动位置,因此需要事先考虑好安装位置。本文基于Fluent软件对渔业船舶冷冻舱室氨气泄漏过程进行数值模拟,研究氨气在不同泄漏方向和不同泄漏位置下的舱内质量浓度变化。研究表明,泄漏方向的变化对舱顶与舱壁附近监测点的氨气检测影响不大,泄漏位置的改变对监测点的氨气检测影响较大,较高位置处的监测点对氨气检测更为精确,氨气泄漏扩散后在舱壁附近和舱室顶部质量浓度较高。因此,氨气泄漏探测装置最好安装在冷冻舱室偏上位置,舱壁与舱顶附近都需要布置探测装置,有利于确定氨气是否泄漏。     

库湾网栏生态养殖技术要点

库湾网栏养鱼的优点是能充分利用库湾优良的水环境,使水体不断得到更新,鱼的排泄物和食物残渣在水动力作用下及时得到稀释和扩散,养殖成活率高,鱼病少,生长快,饲料系数低,成本低,水产品质量安全,经济效益好,环境污染小。南阳市有大中小各类水库509座,境内宜渔库湾1000多个,仅丹     

棘胸蛙养殖技术之二:棘胸蛙封沟养殖新技术

棘胸蛙因长期处于野生状态,资源有限,产品供不应求,因此,积极开发利用野生动物资源,振兴山区经济的优良品种,受野生为人工驯养,是一项能够使山区人民脱贫致富的养殖业。封沟养蛙,一是能带来显著的经济效益,且产品供不应求;二是增加山地的植被,又能促进棘胸蛙种群,保护了生态平衡,从长远来看具有较大的社会效益和十分广阔的前景。     

鳜鱼不同养殖时期的投饲技巧

鳜鱼自鱼苗开食时就以活鱼苗为饵料，而且不同生长阶段对活饵料的种类的大小有不同的要求，如果供食不及时、数量不能满足或不适口，鳜鱼就会自相残食而被咬死、卡死，或因饥饿而死亡。因此，必须根据鳜鱼不同养殖时期的需求，有计划地生产供给各种不同规格的活饵料鱼，做到时间配合、数量满足、规格配套、品种适宜，才能保证养殖效益的提高。     

Growth of tiger puffer Takifugu rubripes in closed recirculating culture system

ABSTRACT:   Two feeding experiments were conducted to elucidate growth performance of tiger puffer in a 10 m³ water volume closed system. In experiment 1, 1000 fish of 3.5 g average body weight were fed tiger puffer commercial feed twice daily to apparent satiation, 6 days a week for 224 days. Sand-filtered sea water was used and no water was exchanged during the rearing period. Immediately after cutting of lower teeth at day 112, daily feed consumption decreased greatly and 60 fish died in few days. Feeding rates recovered and then decreased gradually as nitrate levels increased from 600–1048 mg N/L. Fish grew to 343 g with 91% survival rate and 87% feed efficiency. Rearing conditions of experiment 2 were similar to experiment 1, except that culture water was exchanged to maintain the nitrate level less than 600 mg N/L during the 224-day experiment. Mortality and reduction of feed consumption occurred immediately after teeth cutting as was observed in experiment 1. Significant reduction of feed intake was not found during other rearing periods. Fish of 3 g grew to 303 g with 91% survival rate and 72% feed efficiency.     

Evaluation of two commercial nitrification accelerators in closed seawater culture systems

Commercial bacterial formulations were added to new seawater aquariums, and their ability to accelerate the establishment of nitrification was compared with untreated controls. Fritz-Zyme No. 9, a liquid formulation, markedly decreased the time to complete oxidation of ammonia but did not accelerate the oxidation of nitrite; Bio-Con CRC-610, a dry formulation, did not accelerate ammonia or nitrite oxidation.     

Oxygen consumption rates of white sturgeon under commercial culture conditions

Oxygen consumption rates of white sturgeon (Acipenser transmontanus) were measured under commercial culture conditions. Mean fish size ranged from 0.09 to 3.8 kg (0.2–8.4 lbs). Mean daily values of oxygen consumption rates ranged from 70–330 mg kg fish⁻¹ h⁻¹. Peak oxygen consumption rates were measured to be as much as twice the mean daily values and were seen to occur in response to feeding for fish fed a ration of less than 2.6% body mass per day. With higher feed rations, peak oxygen consumption rates were a smaller percentage of the mean daily value. Multiple regression analysis showed that 93% of the variations in measured oxygen consumption rate values could be attributed to variations in feed ration.     

7种常用渔药对海水闭合循环系统生物滤器硝化作用的影响

在海水闭合循环系统中加入常用剂量的呋喃唑酮 (C8H7N3 O5)、甲苯咪唑 (C16H13 N3 O3 )、土霉素 (C2 2 H2 4N2 O5.2H2 O)、氯霉素 (C11H12 O5N2 Cl2 )、CuSO4 FeSO4合剂、强氯精 (C3 Cl3 N3 O3 ,有效氯 6 2 .5 % )、甲醛 (CH2 O)等 7种常用渔药 ,确定系统把 10mg/L总氨氮 (NH4 N)硝化至较低水平 (CNH4 N<0 .0 5mg/L ,CNO2 N<0 .0 1mg/L)所需的时间及氧化过程中各主要水质指标的变化 ,并以此作为判断生物滤器的硝化能力是否受到影响的依据。结果表明 ,分别加入甲苯咪唑至 1、2、3mg/L(全水体质量浓度 ,其他同此 )、CuSO4 FeSO4合剂 (0 .5 0 .2 )mg/L、土霉素 1mg/L、氯霉素 1、2、3mg/L均对生物滤器硝化作用无明显影响 ;土霉素 2、3mg/L、强氯精 1mg/L或甲醛 10、2 0、30、4 0mg/L影响生物滤器对亚硝酸氮的氧化 ;分别以呋喃唑酮 1、2、3mg/L、重复添加氯霉素至 3mg/L、重复或直接添加强氯精至 2mg/L都影响氨氮、亚硝酸氮的氧化     

生物絮团在凡纳滨对虾封闭养殖试验中的形成条件及作用效果

本研究尝试将生物絮团技术应用到凡纳滨对虾试验性封闭养殖系统中,筛选生物絮团养殖所需的适宜碳源及其添加量,在此基础上研究生物絮团养殖系统中凡纳滨对虾的适宜养殖密度。结果表明,在养殖密度为150和300尾/m2的凡纳滨对虾养殖系统中,每天按照饲料(蛋白含量42%)投喂量的77%添加蔗糖,生物絮团4d即可形成,在84d的养殖期内,养殖水体的氨氮和亚硝酸氮浓度均维持在较低水平,对虾成活率在80%以上,取得较好的养殖收获。     

Tolerance of juvenile black sea bass Centropristis striata to acute ammonia and nitrite exposure at various salinities

ABSTRACT:   Experiments were conducted to determine the acute tolerance of juvenile (mean weight ± standard error, 9.9 ± 0.9 g) black sea bass Centropristis striata to environmental un-ionized ammonia-nitrogen (NH₃-N) and nitrite-nitrogen (NO₂-N) exposure at various salinities. Specifically, median lethal concentrations (LC50 values) of NH₃-N and NO₂-N at 24, 48 and 96 h of exposure were determined at salinities of 10, 20 and 30 g/L at 22°C. With the exception of LC50 values determined at 48 h, median lethal concentrations of NH₃-N to black sea bass were not influenced by environmental salinity; 24, 48, and 96 h LC50 values ranged from 0.81 to 0.85, 0.65–0.77, and 0.46–0.54 mg-NH₃-N/L, respectively. In contrast, tolerance of black sea bass to environmental NO₂-N was compromised at reduced salinities. Median lethal concentrations of NO₂-N to fish at 24, 48 and 96 h of exposure ranged from 288.3 to 429.0, 258.4 to 358.8 and 190.0 to 241.9 mg-NO₂-N/L, respectively. Results indicate that while juvenile black sea bass are relatively sensitive to acute NH₃-N exposure, they are highly resistant to NO₂-N exposure.     

Ultraviolet light control of Ichthyophthirius multifiliis Fouquet in a closed fish culture recirculation system

Abstract. A closed fish culture recirculation system consisting of 36 20-gallon aquaria in series with a rotating plate biofilter, a diatomaceous earth filter, and an ultraviolet (UV) light sterilizer was evaluated for the effectiveness of UV light in preventing spread of Ichthyophthirius multifiliis . Water from the aquaria, the reservoir, and a valve 29 cm beyond the UV light source was analysed bacteriologically to assess its effectiveness. The spread of I multifiliis from one aquarium to another was controlled with 91 900 μW s/cm⁸ of UV light. No significant differences in the bacterial counts from the water of the reservoir or the aquaria could be demonstrated when the UV light was either on or off, although a significant difference could be demonstrated between the sterilizer effluent and the reservoir and aquaria.     

封闭循环流水养殖的花鳗鲡脂肪酸特征分析

为探寻封闭循环流水养殖模式下养殖的较大型(≥2 kg)花鳗鲡(Anguilla marmorata)各可食部的脂肪酸特征,利用索氏抽提法获得各部位的粗脂肪,以37种脂肪酸甲酯混标标准品为标准,气相色谱外标法检测脂肪酸的组成。检测结果显示,鱼皮中粗脂肪含量最高为26.96%,鱼肉的粗脂肪含量为10.36%;不同可食部的脂肪酸组成基本相似,饱和脂肪酸9种,单不饱和脂肪酸6种,多不饱和脂肪酸8种,饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸间的比例大约都为1∶3∶1,三大类脂肪酸中含量最高的分别为软脂酸C16∶0、油酸C18∶1n9c和二十二碳六烯酸C22∶6n3,油酸在不同可食部中均超过20 g/100 g总脂,C22∶6n3(DHA)在不同可食部中含量在4.42~5.59 g/100 g总脂之间。研究表明,较大型花鳗鲡是人体所需脂肪酸的良好食物来源。     

Acute tolerance of juvenile Florida pompano, Trachinotus carolinus L., to ammonia and nitrite at various salinities

The acute tolerance of juvenile Florida pompano Trachinotus carolinus L. (mean weight±SE=8.1±0.5 g) to environmental unionized ammonia‐nitrogen (NH₃‐N) and nitrite‐nitrogen (NO₂‐N) at various salinities was determined via a series of static exposure trials. Median‐lethal concentrations (LC₅₀ values) of NH₃‐N and NO₂‐N at 24, 48, and 96 h of exposure were calculated at salinities of 6.3, 12.5 and 25.0 g L^?1 at 28 °C (pH=8.23–8.36). Tolerance of pompano to acute NH₃‐N exposure was not affected by salinity, with 24, 48 and 96 h LC₅₀ values ranging from 1.05 to 1.12, 1.00 to 1.08 and 0.95 to 1.01 mg NH₃‐N L^?1 respectively. Regarding NO₂‐N, tolerance of pompano to this environmental toxicant was compromised at reduced salinities. Median‐lethal concentrations of NO₂‐N to pompano at 24, 48 and 96 h of exposure ranged from 67.4 to 220.1, 56.9 to 140.7 and 16.7 to 34.2 mg NO₂‐N L^?1 respectively. The results of this study indicate that juvenile Florida pompano are relatively sensitive to acute NH₃‐N and NO₂‐N exposure, and in the case of the latter, especially at lower salinities.     

Management of a closed brackish water system for high-density fish culture by biological and chemical water treatment

During a 1-year operation of a warm water recycling system (salinity about 8‰) sufficient water quality was maintained under high stocking density conditions using Tilapia and the European eel as potential candidates for intensive farming. The final fish: water ratio was 1 : 23 (or 43.5 g fish per 1 water) for the whole experimental culture unit. The total water volume of the system was about 5 m³. The water treatment unit held 52% of the total volume, whereby 46% was available for fish culture. Combined biological (trickling filter with Hydropack-foil) and chemical (ozonation) water treatment proved to be useful to meet water quality requirements under these rearing conditions. After an initial conditioning period of the biofilter, BOD varied from 4.5 to 6.0 mg O₂/l, ammonium levels were maintained at less than 1 mg/l and nitrite concentrations averaged 1 mg/l. The average efficiency (oxidation rate) of the biofilter for NH₄⁺-and NO₂^?-oxidation was 31% and 13.2%, respectively. The pH was stabilized slightly above 7.0 when a denitrification unit was connected to the system. Nitrate concentration of the system levelled of between 200 and 400 mg/l and was regulated by the addition of an electron donator (first glucose solution, then methanol) to the denitrification unit; the elimination rate averaged 50% with a maximum of 98%. High nitrite levels were avoided by ozone treatment of the recycled water. The accumulation of low-biodegradable substances was also successfully counteracted by ozonation. Fish growth rates of about 30% per month at high stocking densiteis were reached for Tilapia at a fish: water ratio of 1 : 4.6 (217 g fish per 1 water), indicating that a combination of biological water treatment and ozonation supports intensive fish culture in a closed aquaculture system.     

封闭式循环水养殖牙鲆鱼技术初步研究

将新功能滤料、高效混合净水菌团、水质自动监测及控制3项关键技术及配套设备用于封闭式循环水养殖牙鲆鱼。结果表明，封闭循环组成活率可达到90％－95．1％，平均产量为32．2kg/m^2。较对照组养殖密度增加75．6％－102．7％，成活率提高14％－17％，平均产量增加145％－187．5％。充分利用有限的水体，避免海水二次污染，利于环境保护。     

生物絮团对凡纳滨对虾养殖过程中氨氮和亚硝酸氮含量的影响

本实验以非生物絮团养殖模式作为对照,研究了生物絮团凡纳滨对虾养殖模式中,水质因子氨氮和亚硝酸氮的变化规律。结果表明:试验组的生物絮团沉积量至第35天达到峰值(15.93±0.31)m L/L,而后保持相对稳定状态,对照组的生物絮团量一直处于极低水平(1.5 m L/L),两组之间差异显著(P0.05);对照组氨氮含量至第35天达到峰值(1.05±0.19)mg/L,试验组氨氮含量增加缓慢,至第60天时仅为(0.37±0.04)mg/L,显著低于对照组(P0.05);在实验的前15天,实验组和对照组的亚硝酸氮含量无显著差异(P0.05),随后试验组亚硝酸氮含量增速减慢并趋于稳定,而对照组则直线上升,对照组亚硝酸氮含量显著高于试验组(P0.05)。     

Growth,immunity and ammonia excretion of albino and normal Apostichopus japonicus (Selenka) feeding with various experimental diets

An experiment was conducted to evaluate the effects of six experimental diets on growth performance, ammonia excretion and immunity of albino and normal Apostichopus japonicus. A factorial design was used, the factors being type of diets (six levels) and colour of A. japonicus (two levels). A total of 30 randomly selected albino A. japonicus were housed in each (60 × 50 × 30 cm³) of 18 blue plastic aquaria to form six groups in triplicate, and the same set‐up was used for the normal A. japonicus. Each group of animals was fed with one of the six experimental diets. Apparent dry matter digestibility (ADMD) and apparent crude protein digestibility (ACPD) were analysed using acid‐insoluble ash (AIA) content method. At the end of the experiment, all A. japonicus were harvested and weighed to calculate growth parameters. After weighing, six individuals from each aquarium were randomly sampled for immune indices. Results indicated that all growth parameters of A. japonicus increased with decreasing nutrient content in their diets (p < .01), whereas an opposite result was observed in case of the ammonia‐nitrogen production by A. japonicus. Normal A. japonicus grew better (p < .01) and produced lower (p < .01) quantity of ammonia nitrogen compared to the albino A. japonicus. Immunity particularly superoxide dismutase and lysozyme activities was higher (p < .05) in normal compared to albino A. japonicus. Considering all measured variables, D1 (diet containing crude protein, crude lipid, carbohydrate and crude ash 51.8, 8.7, 231.3, 708.2 g/kg, respectively) was the best diet among all experimental diets. More research is still needed to optimize nutrients in the diet of A. japonicus, as this study does not provide information about critical threshold level of nutrients in diets. Until then, diet D1 can be recommended for A. japonicus aquaculture.     

A comparison of larval production of the northern scallop,Argopecten purpuratus,in closed and recirculating culture systems

Northern scallop Argopecten purpuratus aquaculture relies on an efficient all year-round larval supply. Larvae are generally produced in closed aquaculture systems (CAS) using the batch techniques with periodical water changes. For instance, survival rates are greatly variable and can range from 0 to 80% making production of scallop larvae uncertain. The main goal of this study was to determine the feasibility of rearing scallop larvae in a recirculating aquacultural system (RAS), and secondarily to compare scallop larval growth rate and time length to reach the settling stage when reared with a traditional Chilean CAS technique and in a novel RAS technique in an industrial-like approach.Several batches of larvae were cultured in CAS and RAS. Larvae were fed on Isochrysis galbana cultured in 35-L tubular photobioreactors. Growth rates were significantly different (F_11,2840 = 274.66; p < 0.001). All scallop larvae cultured in CAS showed lower growth rates ranging within 4.49 and 7.30 μm day^?1 and protracted period of culture until settlement (at least 10 more culture days) than those reared in RAS (growth rates between 9.56 and 13.15 μm day^?1). However, final survival (from D-larvae until settlement) of larvae reared in CAS showed higher values than those values recorded for larvae cultured on RAS. Higher growth rates observed in RAS could be attributed to a reduction in daily manipulation of the animals and/or more feed availability as well as higher temperatures and a steady state conditions in water quality. Even though, the reduction in time for rearing larvae until settlement in RAS was high, the comparison between systems is more significant in view of the reduction in make up seawater from 100% of system volume (CAS) to less than 10% of system volume (RAS). Therefore, RAS was independent from daily water quality variation from natural seawater by increasing water retention time, and with that improve water quality steady state conditions. Results of this research show that a more efficient use of water and heating systems than generally used in the Chilean hatchery industry is achievable. This is an important result since it could lead to significant reductions in the cost of operating a scallop hatchery, however further work is required to accurately compare the two systems (CAS and RAS). The main result from this research is that scallop larvae can be cultivated using recirculating aquaculture systems (RAS) as a method to increase production. The information reported in this paper will be useful for the improvement of scallop larvae culture techniques under controlled conditions.