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1.
平均尾重９３ｇ的当年假睛东方Ｔｕｎ鱼种，在室内以１ｍ＾３水体１６尾、１７尾、１８尾、２０发愤的密度进行越冬，在第天换水１／２、每隔２ｈ充气３０ｍｉｎ、水温保持１２～１３℃的情况下，饵料为冷冻鲜杂鱼，经过１７２天越冬期，增重率为２６％，平均成活率为９１．１％。  相似文献   

2.
４只网箱放养规格５０ｇ／尾淡水白鲳越冬鱼种和１２５ｇ／尾的早繁鱼种，共生产商品鱼１３５５７６５ｋｇ，净单产２０２４６ｋｇ／ｍ２，平均尾重８１１ｇ和６５３ｇ，成活率９６％，饵料系数１６４，投入产出比１∶２９４。网箱加遮光罩布可使淡水白鲳体色鲜艳。  相似文献   

3.
傻鲫网箱育种和越冬试验   总被引：1，自引：0，他引：1  
利用２只（５０ｍ＾２）网箱进行傻鲫鱼鱼种培育和越冬试验，效果良好。鱼种单产７７．５ｋｇ／ｍ＾２，规格为８０．４ｇ／尾，饲养成活率达９２．７％，饵料系数１．５２。经１４０ｄ越冬，成活率９０％，越冬个体减重率１０％。  相似文献   

4.
利用深井水作为越冬水源,控制水温在１６～２１℃,在塑料大棚内３口面积各为２０ｍ＾２水泥池内放养奥利亚罗非鱼亲鱼６５４尾,１口面积为２９ｍ＾２的水泥人放养鱼苗１３００尾,经过１６５ｄ的越冬饲养,最后存活亲鱼６１５尾,成活率９４％,鱼苗１１８０尾,成活率９０．８％。  相似文献   

5.
朱克遵 《齐鲁渔业》1997,14(2):32-34
１９９５年１１月至１９９６年５月，进行了较大规模的池塘鲈种自然越冬生产性试验，本文仅报告一口０．１３ｈｍ＾２微咸水池塘冬技术及效果，投入鲈种３０００尾，越冬后出池２１４０尾越冬成活率７１．３３％，平均全长和体重分别增加２．９ｃｍ和２９．７％，对池塘自然越冬与塑料大棚保温越冬进行了经济效益比较。  相似文献   

6.
１９９２年一口面积３３３３ｍ＾２的池塘直接放养建鲤乌仔１．７５万尾，放养鲢夏花１．２万尾，经过１４３天饲养，当年共产鱼６６１７ｋｇ，折合单产１９８４５ｋｇ／，占８０％，平均规格达到４５８ｇ／尾，成活率６５．８％，饲料系数２．２３；产鲢鱼种１３４５ｋｇ，占２０％，平均规格１６１ｇ，成活率７０％，共盈利２３５４０．１５元，投入产出比１：２．１。  相似文献   

7.
在面积０．６７ｈｍ＾２，水深１．５ｍ的池塘中投放体长为３ｃｍ的斑点叉尾Ｈｕｉ鱼苗９万尾，用干红虫饲养１８８ｄ，共产大规格斑点叉尾Ｈｕｉ鱼种１ １７４ｋｇ，平均规格６２尾／ｋｇ，养殖成活率８７．５％，每６６７ｍ＾２获利３ ７８０元，投入产出比为１：１．８７。  相似文献   

8.
当气温降到２０℃时，要把亲虾移入越冬池。越冬池放养密度以８～１０尾／为宜。越冬池做好日常管理，才能提高亲虾越冬的成活率。１水温当年冬季到翌年２月，水温应控制在２０～２２℃，不要低于１８℃或高于２３℃，升温时要缓慢进行，每ｈ升温不超过１℃。２充气与换水...  相似文献   

9.
淡水白鲳网箱培育鱼种试验   总被引：1，自引：0，他引：1  
本试验在电厂冷却池中进行，设置网箱２只，放养尾重０．４ｇ的鱼种，共１０９００尾，培育４４天，出箱规格５４．８４ｇ／尾，平均单产３７．９１ｋｇ／ｍ＾３，成活率７６．１％。全部投喂自行配制的颗粒饵料，饵料系数为１．６３，投放产出比为１：２．５２。  相似文献   

10.
１９９３年我们采用小池塘、高密度进行加州鲈鱼苗种培育，共投放平均全长２．１厘米的鱼苗６．４万尾，经一个月饲养，平均全长达５．３厘米，总成活率为８３．６％，亩培苗能力达５．３万尾。同时进行投喂不同饮料的生长对比试验；投喂鲜活淼蚤的苗种比投喂鱼浆、鱼糜的苗种生长快１．２倍，成活率高１６．６％。  相似文献   

11.
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.  相似文献   

12.
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13.
Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.  相似文献   

14.
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.  相似文献   

15.
The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.  相似文献   

16.
Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL?1 (1.25 ng well?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.  相似文献   

17.
Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).  相似文献   

18.
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19.
A 5 × 3 factorial growth trial was conducted to evaluate optimal dietary protein and lipid levels (dietary protein level, DP; dietary lipid level, DL) for juvenile Sillago sihama (S. sihama) (2.0 ± 0.02 g, initial weight). Fish were fed 15 diets containing 5 DPs (350, 400, 450, 500 and 550 g/kg) and 3 DLs (60, 90 and 120 g/kg) for 8 weeks. The interaction between proteins and lipids significantly influenced the feed conversion ratio, condition factor, body composition, antioxidant indices and lipase activity (p < .05). DP 450 g/kg showed the highest average final body weight. DPs 500 and 550 g/kg significantly decreased the protein efficiency ratio (p < .05). DL 120 g/kg showed the highest percentage weight gain. The low feed conversion ratio was found in diets P45L12, P55L9 and P55L12. Diet P45L12 showed high superoxide dismutase activities. DP 450 g/kg showed the lowest average malondialdehyde content. Lipase activity was increased by increasing DP (p < .05) with a fall at DP 550 g/kg. Under the present experimental conditions, the optimal DP for S. sihama was 450 g/kg under the DL 120 g/kg.  相似文献   

20.
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.  相似文献   

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