匙吻鲟苗种规模化培育技术

2010年4月14日至6月1日在湖北宜昌进行了匙吻鲟苗种的规模化培育试验示范。鱼苗培育在室内水槽内进行,放养密度800～1000尾/m2,改善水温、溶氧、流速等养殖条件,适时投喂适口饵料生物,经过15d养殖,获4cm左右的鱼种47.12万尾,成活率95%;鱼种培育在水库坝下池塘进行,放养密度30万～40万尾/hm2,以...     

花鳗鲡苗种培育技术

为探索花鳗鲡的苗种培育技术,2013年在温棚水泥池中进行了花鳗鲡苗种的培育试验。试验水温在28~30℃,每池放养苗种12万尾,放养密度500尾/m2。放养后60 d内饲喂水丝蚓,60 d后投喂鳗鱼配合饲料。试验结果:经过150 d的培育,投喂水丝蚓期间的饵料系数为6.65,成活率为99%;投喂配合饲料期间的饲料系数为1.70,成活率85%。     

粗唇鮠鱼种人工饲料驯化培育

采用投喂人工配合饲料进行粗唇(鱼危)鱼种培育试验。结果表明:在普通养鱼池塘,放养平均规格1.8-2.2 cm/尾的粗唇(鱼危)苗种,放养密度15-45尾/m~2,经驯化投喂饲料粗蛋白42%的人工配合饲料,经120 d养殖期,粗唇觥平均规格为126-213尾/kg。     

南美鲱鱼鱼种培育试验初报

在 3口 300 m~2的池子中进行南美鲱鱼鱼种的培育试验,鱼苗放养规格为全长 2-3cm,放养密度为2200尾/口,采取微流水培育。投喂自制的团状饲料,粗蛋白含量25-30％。经过113天养殖,平均全长21.3cm,平均体重165.2g:其中最大个体全长26.2cm,体重261g;最小个体南美鲱鱼全长14.3cm,体重49.4g;.日平均增重1.46g.成活率95％,饵料系数1.7-1.8。     

黄颡鱼池塘规模化苗种培育技术研究

池塘放养3 000万尾黄颡鱼水花,通过50 d的养殖试验,通过天然饵料的培养、适当的人工投喂及池塘生态环境调控等措施,获体长5⁸ cm鱼种600万尾,成活率达20%。     

长吻鮠网箱养殖试验

2005年网箱培育长吻鮠冬片鱼种,应用5 m×5 m×3.5 m的网箱,放养规格为3~4 cm/尾的长吻鮠夏花鱼种,放养密度56~790尾/m2,投喂粗蛋白为42%~46%的配合饲料,经7个月养殖,长吻鮠鱼种平均规格达165g/尾,成活率82.5%,单产9 kg/m2,饲料系数1.26,投入产出比1∶2.04;2006年网箱养殖长吻鮠商品鱼,应用5 m×5 m×4.5 m的网箱,放养规格为133 g/尾左右的长吻鮠冬片鱼种,放养密度32~50尾/m2,投喂粗蛋白为42%~43%的配合饲料,经6个半月时间的养殖期,养成个体规格在0.5kg/尾以上的长吻鮠商品鱼比例达86%以上,成活率82.6%~87.0%,饲料系数1.38,单产22.83~26.24 kg/m2,投入产出比1∶1.59。     

哲罗鱼流水池养殖试验

2007年8月5日至2009年12月1日进行了流水池塘哲罗鱼无公害商品鱼规模化养殖试验,投喂人工配合饲料,定期进行生长测定.水温7.8～13.0℃,平均全长3.5 cm、体质量2.0 g/尾的哲罗鱼鱼苗经330d饲养,平均体质量68g/尾,成活率82.4%;平均体质量68g/尾的哲罗鱼鱼种经516d 饲养,平均体质量840g/尾,成活率76.3%,平均单产57.5 kg/m3,     

刀鲚当年鱼种池塘培育试验

为了提高刀鲚当年鱼种池塘培育的成活率,根据其生物学特性,将鱼种按不同密度放养,进行刀鲚当年鱼种池塘培育技术研究。3年的池塘培育结果显示:2016年,按2500尾/亩(15亩=1 hm~2,下同)的养殖密度放养刀鲚当年鱼种,经过141～146 d的培育,其体长增至11.21～11.43 cm,体质量增至4.23～4.62 g,成活率在69.3%～88.0%;2017年,按3750尾/亩的养殖密度放养刀鲚当年鱼种,经过152～157 d的培育,其体长增至11.32～11.65 cm,体质量增至4.44～4.88 g,成活率在42.1%～77.9%;2018年,按5875尾/亩的养殖密度放养刀鲚当年鱼种,经过180 d的培育,其体长增至11.01～11.04 cm,体质量增至2.41～2.44 g,成活率在57.5%～65.1%。结果表明,随着养殖密度提高,刀鲚当年鱼种的成活率呈下降趋势,天然适口活体饵料数量对刀鲚当年鱼种养殖密度的设定以及成活率有一定的影响。     

翘嘴红鲌池塘苗种培育技术

翘嘴红鲌夏花培育采用肥水下塘、豆浆与水花料投喂的育苗方法,简易可行,共投放水花鱼苗160万尾,经28天培育,夏花鱼种平均全长2.96cm,获夏花鱼种131.5万尾,成活率82.2%。每667m~2放养夏花鱼种1.5万尾,采用单养结合驯化摄食膨化颗粒料的饲养方式,经过5个月的饲养,冬片鱼种个体平均体重13.1g,平均全长12.77cm,成活率达95%。     

水库网箱不同饵料养殖匙吻鲟试验

在水库网箱中进行了3种不同饵料养殖匙吻鲟试验,分别为不投饵但灯光诱饵、投喂鱼块和投配合饲料。初放鱼种平均体长16~18 cm,平均体重20~25g,放养密度为7.5~22.5尾/m2。经过近8个月的饲养,养殖成活率平均94.4%。结果显示,配合饲料组的生长最快,平均体重为1.26 kg;鱼块组的生长次之,平均体重0.78 kg;不投饵组平均体重仅0.42 kg。     

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.     

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.     

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.     

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.     

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.