北方地区南美白对虾与罗氏沼虾轮养试验

南美白对虾与罗氏沼虾生长快、易饲养,在南方1年可以养多茬。2001年,我们在日照市进行了2者的轮养试验,3.6亩淡水虾池共产南美白对虾480 kg,罗氏沼虾350 kg,总产值18 950元,亩均纯利3 000余元。试验证明,在北方进行南美白对虾与罗氏沼虾轮养是完全     

滨海滩涂南美白对虾与罗氏沼虾生态混养模式研究

正本研究通过对慈溪地区南美白对虾养殖池塘混养不同密度罗氏沼虾池塘水质、浮游植物、南美白对虾生长、饵料系数、罗氏沼虾产量以及经济效益进行了研究,旨在建立南美白对虾与罗氏沼虾混养新模式,以期为长三角地区南美白对虾科学养殖提供指导和依据。一、材料和方法1.试验条件本试验在浙江省慈溪市龙武渔业专业合作社进行,选择9个面积约10亩的养殖池塘,池塘深度为1.2米,每口池塘配备1.5千瓦     

南美白对虾养殖池塘高效生态套养技术

<正>近几年,我地区开展的南美白对虾养殖出现了一些新问题:池塘单养模式发病率高且难以控制,与罗氏沼虾混养,南美白对虾的产量往往低于罗氏沼虾的产量、对控制病害发生的效果仍然不明显。因此,有必要对现有的养殖模式进行改进,通过调整混养模式中两虾的放养比例,以提高南美白对虾的产量。通过增放甲鱼等品种,有效防控病害发生、增加辅助产出,从而达到提高整个养殖产量和效益的目的。南通市通州区胖磊养殖场连续几年开展了南美白对虾套放罗氏沼虾、甲鱼和花白鲢的养殖模式,不但实现了病害的零发生、获得了白对虾的高产,还增加了罗氏沼虾,尤其是甲鱼的收益,2014年亩收益达10417元。现将该养殖模式的情况总结如下。     

罗氏沼虾、南美白对虾池套养草鱼高产技术试验

2009年4月至2010年12月进行南美白对虾与罗氏沼虾池套养草鱼试验,二口试验池共5.0×667m2;平均每667m2产南美白对虾商品虾735kg,罗氏沼虾438kg,草鱼44kg,平均每667m2产值4.8×104元,利润1.6×104元,经济效益良好。     

肇庆种茜养虾模式

<正>珠海斗门区曾是广东养殖罗氏沼虾的主产区,2000年后逐渐转向养殖南美白对虾,近年来南美白对虾歉产面积扩大,养殖户又渐渐重视养殖罗氏沼虾。然而十多年来罗氏沼虾的养殖环境和养殖方法都在变化,为此笔者组织养殖户前往肇庆参观学习,从中得到了启发。肇庆罗氏沼虾养殖集中在高要,面积约5万亩,是广东最大的养殖区。肇庆近年来摸索和推广"种茜养虾"的方法,平均每亩投苗2万尾~3万尾,     

罗氏沼虾育苗水质研究的若干进展

本文综述国内有关罗氏沼虾育苗水质及调控的研究进展,主要包括人工配制海水中K+、Ca2+、Mg2+的浓度和比例,三态氮、溶解氧、盐度、H2S等主要水质指标的研究成果;从生物、化学、物理和综合方法四方面归纳、总结了罗氏沼虾育苗水质处理方法的研究成果.     

天津地区罗氏沼虾养殖试验(下)

4.成虾养殖(1)养殖模式的选择。在养殖模式上采用主养和混养的模式。主养模式分为两种,一种采用温棚养殖罗氏沼虾,面积2.5亩;另一种采用池塘养殖罗氏沼虾,面积100亩(表2)。混养模式分为两种,一种采用主养南美白对虾混养罗氏沼虾,南美白对虾投放密度除呈祥水产养殖合作社4.1万尾/亩外,其余为2万尾/亩,面积1 375亩;另一种采用主养黄颡鱼混养罗氏沼虾,黄颡鱼投放密度为1.1万尾/亩,面积22亩(表3)。     

罗氏沼虾苗培育温棚 综合利用技术

2001年,我们对净水面2 600m2的4座罗氏沼虾苗培育温棚进行了全年养殖(暂养)试验,第1茬温棚暂养罗氏沼虾苗试验,第2茬露天池塘养殖南美白对虾试验,第3茬温棚暂养罗氏沼虾成虾试验,第4茬温棚养殖青虾试验。全年实际使用温棚259天,实现产值296 805     

南美白对虾土池大棚套养罗氏沼虾关键技术

<正>南美白对虾是余姚市的主导养殖品种,全市南美白对虾养殖面积1万多亩。近年来,由于南美白对虾养殖病害多发,养殖效益不景气,养殖企业开始寻求新的养殖模式,以增加养殖效益、减少养殖损失,南美白对虾套养罗氏沼虾土池大棚养殖模式应运而生。以余姚市海深特种水产养殖场2018年9#土池大棚塘为例,该池塘土壤属于海涂盐碱地,面积6亩,3月28日放养南美白对虾苗80万尾进行标粗,1个月后将48万尾翻到隔壁外塘放养,剩余的在土池大棚塘中留养,土池大棚中再放养规格2～3厘米的罗氏沼虾苗12万尾。南美白对虾在10月15日捕完,产量3118.5千克(不包括翻出部分),销售收入122050元;罗氏沼虾在10月30日清塘捕完,产量1000千克,销售收入     

人工半咸水中Ca2+、Mg2+、K+含量对罗氏沼虾育苗的影响

运用正交设计研究了罗氏沼虾蚤状幼体培育的人工半咸水中Ca2 、Mg2 、K 的适宜含量。试验结果以育成变态苗尾数为分析指标 ,其最适含量分别为Ca2 2 2 0Mg/L、Mg2 35 0Mg/L、K 185mg/L ,因素主次顺序为Mg2 >Ca2 >K 。     

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.     

美人鱼发光杆菌对凡纳滨对虾非特异性 免疫功能及抗病力的影响

在基础饲料中分别添加0.1%和1%美人鱼发光杆菌灭活菌、0.1%美人鱼发光杆菌活菌配制成3种免疫实验饲料,以基础饲料为空白对照组饲料,每组设3个平行样。对个体质量为(4.83±0.36)g的凡纳滨对虾进行为期20 d的饲养实验,分别在0、5、10、15和20d进行取样,以血清中的酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)和溶菌酶(UL)活性为免疫指标,探讨了美人鱼发光杆菌作为免疫制剂对凡纳滨对虾非特异性免疫效应的影响;在投喂免疫饲料后的第22天,按0.004 2 kg/kg体重的剂量,直接投喂对虾白斑综合征病毒(WSSV)病料,并记录累积死亡率。结果表明,美人鱼发光杆菌免疫实验组对凡纳滨对虾血清中PO、ACP、AKP、UL和SOD活性影响明显高于对照组,并且在饲料中添加美人鱼发光杆菌后,明显提高了对虾抵御WSSV感染的能力。其中0.1%美人鱼发光杆菌活菌实验组的抗病毒感染能力最强,WSSV感染14d内累计死亡率为63.3%±5.8%;而对照组为96.7%±3.3%。研究表明,美人鱼发光杆菌添加在对虾饲料中能提高凡纳滨对虾非特异性免疫水平,增强抵抗疾病的能力,将其作为对虾免疫增强剂具有良好的应用前景。     

Effects of Spirulina platensis as a feed additive on growth and coloration of blue dolphin cichlids (Cyrtocara moorii Boulunger, 1902)

This study was carried out to investigate the effects of replacing fish meal with dietary Spirulina as a feed supplement on the growth performance and coloration of blue dolphin cichlids (Cyrtocara moorii). Five isonitrogenous (47% crude protein) and isocaloric (17.36 kJ/g digestible energy) diets were for formulated to replace FM with 0, 5, 10, 15 and 20% Spirulina (designated as Control, SP5, SP10, SP15 and SP20 respectively) and fed to the fish (initial body weight, 3.15 ± 0.01 g). Fish were randomly distributed into fifteen 120 L aquariums (26.5 ± 1.00°C), 15 fish per aquarium. The diets were tested in triplicate for 12 weeks. Experimental groups were fed twice daily (09:00 and 17:00) by hand to satiation. At the end of the feeding trial, significantly (p < 0.05) higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and lower feed conversion ratio (FCR) were observed in fish fed the SP10 diet when compared to the SP20 diet. There was no significant difference in these parameters between the other groups. The skin coloration of blue dolphin cichlid fed a diet containing Spirulina meal was enhanced. The best coloration was observed in the SP15 group. These impressions were objectively validated by chemical determinations of carotenoids extracted from fish skins and passed statistical tests of significance. The study findings show that Spirulina meal does not diminish growth rates except at very high levels.     

Dietary thiamin and pyridoxine requirements of fingerling Indian major carp,Cirrhinus mrigala (Hamilton)

Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg^?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg^?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg^?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg^?1 diet (0.096–0.179 μg thiamin kJ^?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg^?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg^?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg^?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg^?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.     

Sea bream culture in Egypt; status, constraints and potential

Marine fish farming in Egypt began in 1976 with the culture of gilthead sea bream, (Sparus aurata) as this fish was notably adaptable to brackish and marine pond conditions. Today, marine fish and shrimp farms amount to about 19,000 ha, out of which 42% is already in production while the rest, i.e., 58% is still under construction. In 1997, cultured gilthead sea bream production of 2,250 tons made up 3% of the 75,000 tons total aquaculture catch. In polyculture, usually with the grey mullet and sea bass, gilthead sea bream contributed 440 kg ha^–1 to the total yield of 1,700 kg ha^–1 (26%) over a period of 16 months. For the same period, the yield of monoculture ponds averaged 100 kg ha^–1, while in marine cages, yields ranged from 4–10 kg m³. In 1996–1997, fry of 0.25–1 g and fingerlings 1–10 g with a total of 3 million, were collected from the wild and 1 million fry were produced in the three marine hatcheries out of the four existing ones. The development of sea bream culture in Egypt is now severely inhibited by the shortage of seeds and adequate feeds. Exports of both sea bream and sea bass, during 1994–1996 averaged 1,300 tons per year.     

A Minchinia mercenariae‐like parasite infects cockles Cerastoderma edule in Galicia (NW Spain)

The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni‐ and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae‐like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae‐like parasites infecting molluscs outside the United States is confirmed.     

A novel approach to denitrification processes in a zero-discharge recirculating system for small-scale urban aquaculture

This paper presents an innovative process to solve the nitrate build-up problem in recirculating aquaculture systems (RAS). The novel aspects of the process lie in a denitrification bioreactor system that uses solid cotton wool as the primary carbon source and a unique degassing chamber. In the latter, the water is physically stripped of dissolved gaseous O₂ (by means of a Venturi vacuum tube), and the subsequent denitrification becomes more efficient due to elimination of the problems of oxygen inhibition of denitrification and aerobic consumption of cotton wool. The cotton wool medium also serves as a physical barrier that traps organic particles, which, in turn, act as an additional carbon source for denitrification. Operation in the proposed system gives an extremely low C/N ratio of 0.82 g of cotton wool/g of nitrate N, which contributes to a significant reduction of biofilter volume. The additional advantage of using solid cotton wool as the carbon source is that it does not release organic residuals into the liquid to be recycled. Operation of the system over a long period consistently produced effluents with low nitrate levels (below 10 mg N/l), and there was only a very small need to replace system water. The overall treatment scheme, also incorporating an aerobic nitrification biofilter and a granular filtration device, produced water of excellent quality, i.e., with near-zero levels of nitrite and ammonia, a sufficiently high pH for aquaculture, and low turbidity. The proposed system thus provides a solution for sustainable small-scale, urban aquaculture operation with a very high recovery of water (over 99%) and minimal waste disposal.     

Fertilization by refrigerator stored sperm of the Indian major carp, Labeo calbasu (Hamilton, 1822)

This study reports on the spermatological properties, and on the development of a protocol for refrigerator storage (4°C) of Labeo calbasu (Hamilton, 1822) sperm for artificial breeding. Volume, motility, concentration and pH of the freshly collected sperm were 2.21 ± 0.53 (μL g^?1 of fish weight) (mean ± SD), 95 ± 1 (%), 1.93 ± 0.44 × 10⁹ (cells mL^?1) and 7.56 ± 0.17 respectively. Sperm activation was evaluated at different osmolalities of NaCl solution, and motility ceased completely when osmolality of the extender was ≥287 mOsmol kg^?1. Sperm retained motility for 24, 72 and 108 h, after refrigerator storage when sperm were undiluted, suspended in Alsever's solution and suspended in Alsever's solution containing 5% methanol respectively. Fertilization rate of fresh eggs with sperm stored at 4°C in Alsever's solution and Alsever's solution containing 5% methanol was 77% and 60% with a hatching rate of 60% and 43% respectively. The fertilization and hatching success of the stored sperm suggests potential to use refrigeration for transporting genetic material to hatcheries for artificial breeding of L. calbasu in Bangladesh.     

Effects of metomidate anaesthesia or transfer to pur sea water on plasma parameters in ammonia-exposed Atlantic salmon (Salmo salar L) in sea water

Atlantic salmon (Salmo salar L) postsmolts weighing 150 ± 53 g were exposed to 14–15 mg l^–1 TA-N (total ammonia-N) in sea water in 1 m³ tanks for 24h. Blood samples were then taken A) immediately after the fish were netted from the exposure tanks and stunned by a blow to the head; B) 2–20 min after the fish were transferred to 15 l of an anaesthetic solution of metomidate in ammonia-free sea water; or C) 2–20 min after the fish were transferred to 15 l of ammonia-free sea water. Plasma TA-N level was 18% lower in the anaesthetised fish compared to in the fish sampled directly from the exposure tanks (p 0.05), and accordingly 16% lower in the fish transferred to pure sea water although this difference was not significant (p = 0.07). Plasma glucose level was higher in the fish transferred to pure sea water than in the fish receiving the two other treatments (p 0.05), but plasma urea, osmolality, Na^{+, Cl–, Ca2+ or Mg2+} levels did not vary significantly between the different treatments. Plasma TA-N level increased with time in the fish in the metomidate solution (p 0.02).