沅水三种常见鱼类趋流行为研究：水电梯级开发的指示意义

为探索水电梯级开发下鱼类的趋流行为,采用自制鱼类游泳能力及代谢测定装置,研究了3种沅水常见鱼类(鲫、大眼鳜和黄颡鱼幼鱼)的趋流游泳能力及代谢特征。结果显示,鲫、大眼鳜和黄颡鱼的相对感应流速分别为(0.79±0.14)、(1.16±0.07)和(0.75±0.09) BL/s,相对偏好游速分别为(2.31±0.11)、(1.86±0.04)和(1.60±0.03) BL/s,相对临界游速分别为(3.43±0.37)、(2.58±0.32)和(2.68±0.13) BL/s。同样条件下黄颡鱼偏好游速、临界游速、呼吸频率和耗氧率均显著低于鲫和大眼鳜。3种鱼呼吸频率、摆尾频率和耗氧率均随流速增加而增加,呈先升高后降低的趋势。在3.0 BL/s流速下,3种鱼呼吸频率均出现峰值。在2.0 BL/s流速下,鲫和大眼鳜摆尾频率和耗氧率出现峰值,而黄颡鱼则在1.5 BL/s流速下出现。随着流速的增加,鲫趋流率从静水组的64.1%增加至4.0 BL/s的100.0%,大眼鳜和黄颡鱼分别从静水组的60.2%和58.9%增加至2.0~3.0 BL/s的100.0%。水流流速显著影响3种鱼的游泳状态。鲫在静水条件下以逆流前进和顺流而下为主。大眼鳜静水和大多数流水条件下以逆流静止状态为主。黄颡鱼在静水组和较低流速组(<1.0 BL/s)长时间保持逆流静止状态,随着流速的增大,逆流静止比例迅速减少,逆流后退时间比例不断增加。研究表明,沅水3种常见鱼类趋流行为的差异性与其生活习性、形态特征、食性和捕食方式以及生活水环境等密切相关。了解3种鱼类趋流行为参数与流速环境条件的对应关系,有助于建立鱼类游泳生物学仿真数据模型,为梯级开发背景下鱼类的运动生理生态适应机制及运动方式的演化研究提供参考。     

沅水3种常见鱼类趋流行为在水电梯级开发中的指示意义

为探索水电梯级开发下鱼类的趋流行为,采用自制鱼类游泳能力及代谢测定装置,研究了3种沅水常见鱼类(鲫、大眼鳜和黄颡鱼幼鱼)的趋流游泳能力及代谢特征。结果显示,鲫、大眼鳜和黄颡鱼的相对感应流速分别为(0.79±0.14)、(1.16±0.07)和(0.75±0.09) BL/s,相对偏好游速分别为(2.31±0.11)、(1.86±0.04)和(1.60±0.03) BL/s,相对临界游速分别为(3.43±0.37)、(2.58±0.32)和(2.68±0.13) BL/s。同样条件下黄颡鱼偏好游速、临界游速、呼吸频率和耗氧率均显著低于鲫和大眼鳜。3种鱼呼吸频率、摆尾频率和耗氧率均随流速增加而增加,呈先升高后降低的趋势。在3.0 BL/s流速下,3种鱼呼吸频率均出现峰值。在2.0 BL/s流速下,鲫和大眼鳜摆尾频率和耗氧率出现峰值,而黄颡鱼则在1.5 BL/s流速下出现。随着流速的增加,鲫趋流率从静水组的64.1%增加至4.0 BL/s的100.0%,大眼鳜和黄颡鱼分别从静水组的60.2%和58.9%增加至2.0～3.0 BL/s的100.0%。水流流速显著影响3种鱼的游泳状态。鲫在静水条件下以逆流前进和顺流而下为主。大眼鳜静水和大多数流水条件下以逆流静止状态为主。黄颡鱼在静水组和较低流速组(1.0 BL/s)长时间保持逆流静止状态,随着流速的增大,逆流静止比例迅速减少,逆流后退时间比例不断增加。研究表明,沅水3种常见鱼类趋流行为的差异性与其生活习性、形态特征、食性和捕食方式以及生活水环境等密切相关。了解3种鱼类趋流行为参数与流速环境条件的对应关系,有助于建立鱼类游泳生物学仿真数据模型,为梯级开发背景下鱼类的运动生理生态适应机制及运动方式的演化研究提供参考。     

北极茴鱼亲鱼耗氧率和窒息点的研究

试验采用流水呼吸室法和静水呼吸室法,测定了北极茴鱼亲鱼在水温8.5~10.5℃条件下的耗氧率和窒息点。结果表明,北极茴鱼耗氧率具有昼夜节律性,耗氧高峰在12:00左右,低谷在6:00左右,最佳生长温度8~15℃。     

北极茴鱼鱼苗耗氧率和窒息点的研究

试验采用流水呼吸室法和静水呼吸室法,测定了北极茴鱼鱼苗在水温6.5～7.5℃条件下的耗氧率和窒息点.结果表明,北极茴鱼鱼苗耗氧率具有昼夜节律性,耗氧高峰在18:00左右,低谷在6:00左右,最佳生长温度7～15℃.     

在开放静止水槽中测定鱼类耗氧率的方法

<正> 鱼类耗氧率的测定,在水产养殖的生产和科研中是一项经常性的基础工作。以往,由于测定设备的复杂,在实际生产中进行得不多。如何在普通水槽中不用特别装置就能测得鱼类耗氧率,乃是养殖界所期望解决的课题。吉原(1954)最早进行了这种试验,他在普通水槽中放入鱼类,成为开放静水式状态,而后从水中氧气的减小率来求取鱼类的耗氧率。诸岡(1967)进一步改进了吉原的方法。我们在这里介绍经诸岡改进的测定鱼类耗氧率的方法。     

温度、体重和昼夜节律对大菱鲆幼鱼代谢的影响

在鱼体重相对恒定时,用流水法测定了温度、昼夜节律对大菱鲆幼鱼耗氧率、氨氮排泄率的影响;在温度相对恒定时,用静水法测定了体重对大菱鲆幼鱼耗氧率、氨氮排泄率,窒息点的影响。结果表明:在实验温度范围内,体重2.0 g的幼鱼,耗氧率随水温升高而上升;10℃时,耗氧率最低,在26℃达到最高;在18℃以上,温度再升高,大菱鲆幼鱼将分配更多的能量用于呼吸代谢。体重2.0 g的大菱鲆幼鱼氨氮排泄率随水温的升高而上升;在10℃时氨氮排泄率最低,26℃达到最高;大菱鲆幼鱼的氨氮排泄比较稳定,但在较高温度水平时大菱鲆幼鱼蛋白质代谢的强度增加。     

短须裂腹鱼幼鱼耗氧率和临界窒息点的测定

采用封闭式呼吸室法对短须裂腹鱼幼鱼的耗氧率和临界窒息点进行测定。结果表明:在19.4℃条件下,短须裂腹鱼幼鱼的临界窒息点为0.720 mg/L,24 h平均耗氧率为0.205 mg/(g·h),昼夜耗氧率差异不明显;在17.2℃时,24 h平均耗氧率为0.135 mg/(g·h),昼夜耗氧率差异不明显;15.3℃时,24 h平均耗氧率为0.112 mg/(g·h),昼夜耗氧率差异不明显。短须裂腹鱼幼鱼的耗氧率随温度的升高而上升。     

温度对鲢耗氧率的影响

采用封闭流水式和开放静水式对不同温度条件下(4～32℃)鲢(Hypophthalmichthys molitrix Cuvier et Valenciennes)成鱼和幼鱼耗氧率进行了研究。封闭流水式的结果表明:成鱼的耗氧量和耗氧率在32℃时最高,分别为80.51mg·尾~(-1)·h~(-1)和94.71mg·kg~(-1)·h~(-1),在8℃时最低,为17.20mg·尾~(-1)·h~(-1)和20.24mg·kg~(-1)·h~(-1)。幼鱼的耗氧量和耗氧率与成鱼有着同样的变化规律,在32℃时最高,分别为5.60mg·尾~(-1)·h~(-1)和112.00mg·kg~(-1)·h~(-1);在4℃最低,为1.01mg·尾~(-1)·h~(-1)和20.12mg·kg~(-1)·h~(-1)。开放静水式测得的成鱼的耗氧率:在32℃时最高,达136.77mg·kg~(-1)·h~(-1),在8℃时最低,为36.08mg·kg~(-1)·h~(-1);幼鱼的耗氧率在32℃时最高达到194.93mg·kg~(-1)·h~(-1),在12℃时最低,为81.18mg·kg~(-1)·h~(-1)。研究结果表明:鲢体重在45.30～1050g范围内时,随着体重的增加,耗氧量增加,耗氧率下降,温度对鲢成鱼和幼鱼的呼吸水平均有显著的影响。     

草鱼在不同的状况下耗氧率的测定

<正> 鱼的耗氧量及其变动,直接或间接地反映鱼的新陈代谢规律,反映鱼的生理和生活状况。因此,研究鱼的耗氧率问题,不仅在养殖方面具有一定理论意义,而且对于鱼的代谢量的研究也是重要的。因为鱼类的大多数代谢活动都和氧的利用有关,鱼类的耗氧率在一定程度上反映了鱼类的代谢水平。于是我们进行了草鱼耗氧     

倒刺鲃鱼种耗氧率和窒息点的初步研究

有关鱼类耗氧率的研究,国内外科研工作者已进行了大量工作。本次实验对不同规格倒刺鲃在不同温度条件下的耗氧率和窒息点进行了测定,旨在了解倒刺鲃的基础代谢水平,为倒刺鲃的生理学和养殖学等研究提供参考资料。     

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.