鮸鱼亲鱼培育及其人工繁殖的研究

采用自然苗培育成的1龄鱼,通过“春肥、夏育、秋繁、冬保”8字方针培育成亲鱼,性成熟率达到95%。经LHRH-A30.8~1.8μg/kg催产并放人产卵池自行产卵,获产率达到96.83%。获受精卵650万余粒,受精率达到52%。受精后21.8 h孵化出鱼苗,孵化率达到70%。     

鳡鱼人工繁殖技术研究

试验亲本来源于长江武汉金口江段及附属湖泊斧头湖、鲁湖的野生鳡鱼，经6个月暂养或两年池塘驯养后，于2005年～2006年6月分4批共11组进行人工繁殖试验，产卵总量1020万粒，受精卵816万粒，孵出水花365万尾。2年试验平均每组次产卵92．7万粒，受精74．2万粒，孵出仔鱼33．1万尾。初步探明了鳡鱼人工繁殖的方法及规律，其催产率、受精率、孵化率分别为80％～100％、30．4％～88．5％、86．3％～88．8％，同时还对影响人工繁殖的相关因素进行了初步探讨。     

影响黄颡鱼繁殖的几点因素

１．产卵时间黄颡鱼在自然条件下，一般于５月底开始产卵活动，一直持续到７月下旬，这一点通过对其性腺发育阶段解剖观察，和在湖泊中捕获最早的一批天然苗一般在７月中旬即可证明，然而若通过人工精养进行产前强化培育，一般可使产卵时间提前１０～１５天左右。２．亲本培育年底起捕时从池塘或湖泊中收集亲本鱼，要求雌鱼５０克以上，雄鱼１００克以上，放入池塘中进行专池培育，只套养少量花白鲢以控制水质。通过以各种冰鲜杂鱼虾、螺蚌肉等动物性肉糜与饲料厂预混料，混合制成含动物蛋白４０％左右的混合饲料投喂，日投喂１～２次，…     

奥尼鱼鱼苗培育和高产养殖技术

奥尼鱼是奥利亚罗非鱼（雄）和尼罗罗非鱼（雌）的杂交一代。由于它具有生长快、易养高产、肉质好的优点，日益受到养殖者和消费者的喜爱。现将奥尼鱼的鱼苗培育及高产养殖技术总结如下。1奥尼色的生物学特性1．1雄性率高奥尼龟雄性率在92％以上。由于雌鱼少，且当年不产卵，次年产卵也少，所以没有因大量繁殖而造成密度过大的情况。1．2生长快、产量高奥尼鱼具有明显的杂交优势。生长快，刚孵出的鱼苗养至0．5公开的上市规格只需5个月；一年可养两次，亩放800至1500尾，年亩产奥尼鱼800～1500公斤。1．3食性杂、易养、易捕1．4抗病、耐缺氧…     

野生黄颡鱼雌鱼产卵前后肌肉脂肪酸的组成

采用毛细管气相色谱法，对贵州锦江河繁殖期产卵前后黄颡鱼肌肉中的脂肪酸组成进行了测定。结果显示：黄颡鱼产卵前后肌肉中脂肪酸种类都比较丰富，含有有22种脂肪酸。油酸（C18：1n-9）所占比例最高，其次是软脂酸（C16：0）、硬脂酸（C18：0）和棕榈酸（C16：In-7），分别占总脂肪酸的40．31％-43．90％、22．94％-25．05％、6．05％-7．75％、6．26％-7．00%。廿碳五烯酸（C20：5n-3，EPA）和廿二碳六烯酸（C22：6n-3，DHA）之和占4．69％～5．38％，其中EPA约占总脂肪酸的1．4％，DHA占3．6％。同产卵前相比，软脂酸（C16：0）、硬脂酸（C18：0）、亚油酸（C18：2n-6）和花生四烯酸（C20：4n-6，ARA）所占比例下降较大，而C15：0、C22：0、亚麻酸（C18：3n-3）的比例显著升高。研究表明在黄颡鱼产卵后的饲料配制中，需要适当添加脂类物质，以恢复其在产卵后的体质。     

池养瓦氏黄颡鱼全人工繁殖的初步研究

2002年5月12日-6月5日，以自繁自育的2龄瓦氏黄颡鱼作亲本，开展大批量全人工繁殖，共催产亲鱼163．8kg，其中雌亲鱼87．5kg，679尾，雄亲鱼76．3kg，323尾。人工产卵率99％，自行产卵率为88％，共产卵约156万粒，平均受精率为54％，孵化率为44％，孵出鱼苗37.8万尾。     

池塘套养名贵鱼高产高效技术推广总结

1996－1997年度我们承担了省丰收计划指导委员会下达的《池塘套养名贵鱼高产高效技术》推广项目。经过广大水产科技人员和养鱼承包户的共同努力，项目全面达到了合同要求，并超额完成计划任务，实现了大面积，大幅度的增产增收增效。1主要技术措施1．1改善养殖条件采用“以劳代资”的办法对池塘进行升级改造，使池塘养殖条件达到了所要求的标准。平均水深基本上能控制在1．8—2．5m。1．2多品种、大规格、高密度。优质化放养鱼种投放鱼种中，仍以放养常规鱼为主，占整个池塘放养量的68．69％，名贵鱼套养比例达到31．31％。细鳞鱼比例占45％…     

家鱼人工授精若干技术问题的探讨

家鱼人工繁殖产卵方式有两种：人工授精和自行产卵,我场则以人工授精为主,几年来,我场广大工人和技术人员以《矛盾论》、《实践论》为武器,狠批刘少奇一类骗子散布的唯心论的先验论,初步掌握了家鱼人工授精方面的基本规律,积累了一些经验。亲鱼产卵率每年都达到95％以上,亲鱼个体取卵数高(每公斤体重的雌鱼产卵达10万左右),经过多年实践,我场有如下几点体会。     

缺帘鱼全人工繁殖技术研究

利用地下井水,通过人工控温,将引进的缺帘鱼鱼种培育成亲鱼,再对亲鱼进行强化培育,待其达性成熟后进行人工催产.较详细地研究了缺帘鱼亲鱼强化培育的条件,亲鱼的雌雄鉴别技术,催产剂的组合和使用剂量.根据试验结果认为,缺帘鱼亲鱼在水泥池内培育能达到性成熟,人为控制环境条件能控制其产卵时间.     

太阳鱼人工杂交繁殖技术研究

利用人工催产、自然产卵受精技术,对30组蓝鳃太阳鱼(♂)和绿鳃太阳鱼(♀)亲鱼成功地进行人工杂交繁殖试验。在第2次注射催产剂36h后亲鱼开始产卵,4d后产卵结束,共产卵9组,产卵率30%,产卵4.95万粒,受精卵约4万粒,受精率约82.2%。经38~50 h孵化,出苗3.4万尾,孵化率85%。获3 cm苗种2.5万尾,成活率73.5%     

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.     

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.     

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.     

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.     

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.     

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).