Comparison of hydraulics and particle removal efficiencies in a mixed cell raceway and Burrows pond rearing system

We compared the hydrodynamics of replicate experimental mixed cell and replicate standard Burrows pond rearing systems at the Dworshak National Fish Hatchery, ID, in an effort to identify methods for improved solids removal. We measured and compared the hydraulic residence time, particle removal efficiency, and measures of velocity using several tools. Computational fluid dynamics was used first to characterize hydraulics in the proposed retrofit that included removal of the traditional Burrows pond dividing wall and establishment of four counter rotating cells with appropriate drains and inlet water jets. Hydraulic residence time was subsequently established in the four full scale test tanks using measures of conductivity of a salt tracer introduced into the systems both with and without fish present. Vertical and horizontal velocities were also measured with acoustic Doppler velocimetry in transects across each of the rearing systems. Finally, we introduced ABS sinking beads that simulated fish solids then followed the kinetics of their removal via the drains to establish relative purge rates. The mixed cell raceway provided higher mean velocities and a more uniform velocity distribution than did the Burrows pond. Vectors revealed well-defined, counter-rotating cells in the mixed cell raceway, and were likely contributing factors in achieving a relatively high particle removal efficiency-88.6% versus 8.0% during the test period. We speculate retrofits of rearing ponds to mixed cell systems will improve both the rearing environments for the fish and solids removal, improving the efficiency and bio-security of fish culture. We recommend further testing in hatchery production trials to evaluate fish physiology and growth.     

西施舌人工育苗及稚贝中间培育技术

西施舌(C o e l o m a c t r aantiquata spengler)俗称海蚌,是一种生长快、个体大、品味好、营养丰富、价值高的名贵海产珍品。福建长乐沿海独特的海洋地理环境和水质特点,使养殖西施舌的肉质脆嫩,味道独特。近年来,西施舌人工育苗生产始终存在规模小、稚贝成活率低等问题,苗种长期得不到解决,严重制约西施舌养殖业的发展。为了突破西施舌规模化人工育苗关,为其浅海养殖提供2cm~4cm幼贝苗种,福建省科委立项进行西施舌规模化人工育苗及稚贝中间培育技术研究,并取得重大突破。一、亲贝来源1.亲贝收集地点长乐市漳港海区。2.亲贝数量共收集30…     

Comparative analysis of flow patterns in aquaculture rectangular tanks with different water inlet characteristics

The objective of the work is to improve the design rules of rectangular aquaculture tanks in order to achieve better culture conditions and improve water use efficiency. Particle tracking velocimetry techniques (PTV) are used to evaluate the flow pattern in the tanks. PTV is a non-intrusive experimental method for investigating fluid flows using tracer particles and measuring a full velocity field in a slice of flow. It is useful for analysing the effect of tank geometries and water inlet and outlet emplacements. Different water entry configurations were compared, including single and multiple waterfalls and centred and tangential submerged entries.

The appearance of dead volumes is especially important in configurations with a single entry. Configuration with a single waterfall entry shows a zone of intense mixing around the inlet occupying a semicircular area with a radius around 2.5 times the water depth. A centred submerged entry generates a poor mixing of entering and remaining water, promoting the existence of short-circuiting streams. When multiple waterfalls are used, the distance between them is shown to have a strong influence on the uniformity of the velocity field, increasing noticeably when the distance between inlets is reduced from 3.8 to 2.5 times the water depth. The average velocities in configurations with multiple waterfalls are very low outside the entrance area, facilitating the sedimentation of biosolids (faeces and non-ingested feed) on the tank bottom. The horizontal tangential inlet allows the achievement of higher and more uniform velocities in the tank, making it easy to prevent the sedimentation of biosolids.     

三疣梭子蟹养殖塘表层底泥异养细菌群落比较研究

采用菌落菌体形态观察和16SrDNA序列比对的方法,对三疣梭子蟹养殖健康塘和病害塘表层底泥中的异养细菌进行了比较研究。分离得到的255株细菌可分为13个菌落类群,33个菌体亚群。对占异养细菌总数34.5%的两个优势亚群(A-NS-SpR亚群,不产芽孢的球杆状菌;B-SF-SR亚群,产芽孢的短杆状菌)的16SrDNA序列分析结果表明,A-NS-SpR亚群属于变形菌门中的2个纲3个科8个属约12个种,其中Halomonas ventosae和Donghicola eburneus两个种数量最多,占该亚群菌株的59.1%。B-SF-SR亚群属于厚壁菌门芽孢菌纲的3个科4个属约12个种,其中Bacillus decolorationis和Halobacillus trueperi两个种数量最多,占该亚群菌株总数的60.6%。从属的水平上讲,Bacillus和Halomonas是优势属。A-NS-SpR亚群在健康塘中的丰度(菌株数量)明显高于病害塘,但多样性(种属数量)差别较小,其中Rhodobacteraceae科在两个塘中的数量差别最大。与此相反,B-SF-SR亚群在健康塘和病害塘中的丰度相当,但健康塘的多样性明显...     

Comparative growth and welfare in rainbow trout reared in recirculating and flow through rearing systems

The objective of this study was to compare fish performance and welfare at different stocking densities in a recirculating system (RS) and a flow through system (FTS) under field conditions. During the 77 days experiment, the fish survival rate was high (99.3%) and stocking density increased from 57 to 98–108 kg m^?3. No significant differences in growth were observed between RS and FTS until day 56. Later, growth decreased in the FTS, while it remained similar to the farm reference at 50 kg m^?3 in the RS. Final weight was 17% higher in RS than in FTS. The maximum carrying capacity of the RS was near 100 kg m^?3, limited by NO₂ increase up to safe level at the end of the experiment, the maximum carrying capacity of the FTS was near 85 kg m^?3, probably limited by CO₂ concentration (17.8 ± 5.7 mg l^?1). In the RS, the relative length index of pectoral and dorsal fins was lower than in the FTS, which may be attributed to the tank hydrodynamics. In both systems, an improvement of the pectoral and dorsal profile was observed at the end of the experiment, attributed to a swimming activity reduction that may have decreased contact between individuals. In the RS, high caudal fin deterioration (50% versus 20% in FTS) was observed irrespective of stocking density, that could be linked to the highest water velocity modifying the fish swimming activity. The results confirm that when water quality is maintained in safe level ranges, high densities can be used in trout RS without fish performance and pectoral or dorsal fin deterioration, but with a major caudal impairment.     

刺参养殖技术之三利用海带育苗池进行刺参亲参培育技术

近几年,随着北方地区刺参养殖面积的不断扩大,养殖户对大规格苗种的需求不断增加,刺参控温育苗应运而生,其关键技术之一就是亲参的培育技术.在此,笔者将利用海带育苗池进行刺参亲参培育技术介绍如下.     

黄颡鱼苗种培育试验

黄颡鱼俗称嘎鱼,属于淡水温水性鱼类,在我国淡水水域广有分布.我国在20世纪末就开始了黄颡鱼的人工繁殖及成鱼养殖工作,但发展一直比较缓慢.主要原因是苗种培育成活率低,特别是1～3cm阶段死亡率相当高,是黄颡鱼养殖死谷,成为黄颡鱼养殖的主要限制因素.有关专家普遍认为该阶段是黄颡鱼的食性转化阶段,死亡原因是因为过渡饵料和过渡方法不当所致,但始终无行之有效的措施,为此许多水产工作者一直在不懈地努力.     

鲟鳇鱼养殖技术之三达氏鳇幼鱼饲养试验

达氏鳇属鲟鱼科,是黑龙江省特产的大型鱼类之一,具有较高的经济价值和学术研究价值.笔者在室内条件采用玻璃钢盆为培育池,对5000尾刚出膜的达氏鳇进行幼鱼培育实验,初步掌握了达氏鳇幼鱼的培育技术要点.     

中华鲟苗种培育初探

为了探索中华鲟的人工饲养技术 ,1999年 11月至 2 0 0 0年 3月 ,我们引进了少量中华鲟稚、幼鱼进行苗种培育试验 ,现将初步研究结果报告如下。1　材料与方法实验鱼分 3次从有关科研保护单位引进。第 1次为稚鱼 ,数量 50 0尾 ,全长 3～ 4ｃｍ ,2 4日龄 ,1999年 11月 16日引进。第 2次为幼鱼 ,数量 10 5尾 ,全长 7～ 10ｃｍ ,1999年 12月 1日引进。第 3次为幼鱼 ,数量 2 0尾 ,全长 12～ 15ｃｍ ,2 0 0 0年 1月5日引进。实验鱼前期放在室内水族箱中饲养 ,后期放在甲鱼温室水泥池中饲养。水族箱中的水源为曝气自来水 ,水泥池的水源为东湖天然水 …     

西施舌人工育苗试验

浙江西施舌的人工育苗以4月下旬至6月中下旬为宜,重视亲贝促熟技术,实行阴干和流水刺激排放精卵,变态期以沙底质上附着为宜。     

黑脊倒刺鲃苗种的高效培育技术

~~黑脊倒刺鲃苗种的高效培育技术@连凤英$福建省长泰县水技站!363900~~福建省教委基金资助项目 (K990 5 8)     

Observations of flow patterns in a model of a marine fish larvae rearing tank

There are few studies on flow fields generated by aerators in fish larvae rearing tanks. The flow varies with aeration rates and tank proportions resulting in different larvae survival rates. The effects of aeration rate and aspect ratio AR (the ratio of liquid depth to tank radius) on overall flow patterns were investigated experimentally using flow visualization techniques. Two distinct types of flow patterns, a single-pair vortex system and a two-pair vortex system, were observed as the value of tank aspect ratio varied from about 1.0 to 2.0. In addition, corner vortex structures were observed in both the region between the free surface and the upper sidewall, and between the bottom wall and the lower sidewall of the tank. On the sidewall, reattachment and separation points were found, which were closely related with these vortex structures.     

青蛤人工育苗试验

青蛤潜居泥沙中生活,移动性小,适宜滩涂养殖,且近几年对其苗种的需求量日益增加,沿海各地均在开展青蛤人工育苗试验和生产。我们于2005年7月-10月底,利用投放较大颗粒的附着基、浮游期采用过滤海水、稚贝附着后改用室外土池流水培育的新工艺,在430m2水体中培育壳长4mm-9mm的青蛤苗种总计1亿粒。     

暗纹东方鲀的小规格鱼种培育技术

<正> 暗纹东方纯属于硬骨鱼纲、鲀形目、鲀科、东方鲀属。其蛋白质含量高,同时还含有多种微量元素,是一种价格较高的鱼类。许多生产单位往往只有1.5cm以下的小规格鱼苗而无大于3cm的鱼种出售。并且1.5cm以下的鱼苗价格相对偏低,而3cm以上价格较高。我们通过两年的摸索,在     

贝类养殖技术之二黑鲍苗种培育技术

黑鲍原系皱纹盘鲍和日本盘鲍的杂交后代，壳形略似皱纹盘鲍，但体螺层高低明显，壳孔4个~5个与外面相通，是我国鲍鱼中个体较大的种类之一。黑鲍作为新引进的养殖品种，已逐渐在南方的一些沿海地区发展起来，成为南方鲍鱼养殖的新品种。本文报道了利用闽南九孔鲍育苗设施、海区渔排和浮筏，进行黑鲍生产性人工苗种培育技术。一、亲贝的选择10月中旬，水温20℃~24℃，挑选海区吊养或陆上养殖的鲍鱼，其壳长6cm以上，活力强且无损伤，性腺外观极为丰满，基部凸出壳缘，末端充满生殖腺而呈纯圆，雌鲍生殖腺多为绿色(少数为褐绿色)，雄鲍生殖腺…     

美国鲥鱼苗种生产技术

美国鲥鱼(Alosasapidissima)英文名称为AmericanShad,隶属于鲱形目、鲱科、鲥属,为滤食性鱼类,以浮游生物为食。美国鲥鱼天然种群分布于北美东部沿海水域,属于广温性、广盐性的溯河性洄游鱼类,平时生活在海里,4月~6月沿江河上溯淡水湖泊进行产卵,生殖后亲鱼仍回归海洋,幼鱼则在     

洄游型大西洋鲑苗种培育技术

大西洋鲑(Salmon salar)属鲑科、鲑属,原产于大西洋北部和北美,分洄游型和陆封型两种,洄游型大西洋鲑是目前世界上最主要的养殖鱼类品种之一,也是目前人工养殖产量最高的冷水性鱼类。洄游型大西洋鲑人工育苗在淡水中进行,成鱼养殖阶段则在海水中进行,这与终生在淡水中养殖的陆封型大西洋鲑有着本质的区别。洄游型大西洋鲑更适于进行集约化养殖,其特点是经济价值高,生长速度快,抗病力强,但由于其在我国没有自然分布,且人工育苗技术难度较大,故在中国目前还没有开展大规模养殖。大连龙胜海洋渔业养殖有限公司于2004年初从美国引进洄游型大西…     

贝类养殖技术之三泥东风螺人工育苗技术

泥东风螺(Babylonia lutosa)隶属软体动物门、腹足纲、前鳃亚纲、新腹足目、蛾螺科、东风螺属,在我国主要分布于福建、广东、广西、海南等地,为肉食性贝类,生活在5m~70m深的海底,自然栖息区域为泥沙质底,适温范围为13℃~33℃,最适生长水温25℃~30℃,盐度适应范围为20‰~34‰,最适盐度为25‰~32‰,也为广盐性、广温性贝类,酸碱度适应范围为pH7.5~8.4。泥东风螺的繁殖期为3月~10月,繁殖高峰期在6月~9月。近年来,国内对泥东风螺人工育苗研究较多,但生产中对泥东风螺人工育苗而获得大量合乎商品规格的较少。广东省湛江市水产技术推广中心站与湛…     

Changes in the bacterial composition of water in a carp rearing tank

The bacteria from an 800-l carp rearing tank were isolated on five different media during a 45-day experimental period. Total viable counts and the variety of groups of bacteria detected in the water increased after the carp were stocked. The Vibrio-Aeromonas group and Bacteroides type A, which were major components in the intestinal tracts of carp, increased after fish were introduced, and decreased after fish were removed.     

贝类养殖技术之二:毛蚶人工育苗技术

毛蚶作为我国重要的海产经济贝类,其自然资源在不断下降,而其市场价格和需求量在不断上涨,这就使毛蚶的人工养殖悄然兴起。为了加速毛蚶人工养殖的发展步伐,2003年,我们进行了毛蚶人工育苗试验,取得了一些成果,现将毛蚶人工育苗技术的要点总结如下:一、相关的生物学特性1.繁殖