混养鲫鱼对罗氏沼虾种虾培育效果的影响

在3口面积各为0.3 hm^2、深度2.0 m的长方形池塘(1#、2#、3#)中放入体长0.7～0.8 cm的罗氏沼虾"南太湖2号"无特定病原种虾,密度为3.0×10~5尾/hm^2;养殖30 d时,2#、3#池塘分别混养质量3～4 g/尾的鲫鱼450、900尾,1#池塘不混养作对照组。经过近110 d的培育,1#、2#、3#池塘"南太湖2号"种虾的平均体质量分别达18.36、18.95、22.6 g,收获量分别达931.5、898.4、842.95 kg,饵料系数分别为1.36、1.53和1.71。试验结果表明,罗氏沼虾"南太湖2号"种虾培育池塘混养合理密度的鲫鱼,虽然影响种虾养殖产量,饲料系数增大,但培育出的种虾个体较大,饱满度较高,作为亲本可以为后期育苗工作的顺利开展打下良好基础。     

Effect of practical diets with different protein levels on the performance of Farfantepenaeus paulensis juveniles nursed in a zero exchange suspended microbial flocs intensive system

Farfantepenaeus paulensis juveniles (72 ± 24 mg), were reared in a suspended microbial flocs system and fed practical diets containing increasing amounts of crude protein (250, 300, 350, 400 and 450 g kg^?1 CP). Development of microbial flocs was promoted by high aeration rates and fertilization with wheat bran and molasses. Flocs were composed of detritus in the form of flocculated matter colonized by heterotrophic bacteria, cocoid and filamentous cyanobacteria, flagellate and ciliate protozoa and rotifers. Proximate composition analysis of the suspended microbial floc showed CP levels of 304 g kg^?1. After 45 days, mean shrimp survival were above 89%, with no significant differences between treatments. Shrimp fed diets with 350 g kg^?1 or higher CP content achieved significant higher (P < 0.05) final weight (0.66–0.68 g), weight gain (0.58–0.61 g) and instantaneous growth rate (0.049–0.050), with feed conversion rates (2.17–2.30) significantly lower (P < 0.05). Results show that, when rearing is carried out in a suspended microbial flocs system, dietary CP levels can be kept at 350 g kg^?1. Furthermore, results confirm that microbial‐based systems allow shrimp culture without compromising the surrounding environment and shows the possible reduction of production costs and fish meal dependence.     

河蟹青虾混养池塘循环水净化效能的初步分析

在河蟹青虾混养池塘构建封闭式循环水养殖系统,并对其净化效果和养殖效益进行了初步研究。结果表明：该系统对水体TN、TP、NH4＋-N和CODMn的平均净化效率分别为27.33%、56.14%、43.91%和39.59%。经湿地净化后的水质能够达到GB3838-2002地表水Ⅲ类排放标准,平均纯收益达53769元/hm2。     

不同光照强度对太平洋鳕仔鱼摄食的影响

研究不同光照强度对太平洋鳕仔鱼摄食的影响。在0～1 000 lx光照范围内,对不同光照强度、摄食不同时间太平洋鳕仔鱼摄食量进行了测定,结果表明:仔鱼500 lx时摄食强度最大,其次为700、300 lx,摄食率在500 lx时最高,并在摄食开始后10 min时达到最大,并随着时间的延长而降低。     

Modelling the transport of particles in the North Sea with reference to sandeel larvae

The transport of particles representing sandeel larvae in the North Sea is simulated with a three-dimensional circulation model for the years 1976 to 1990. A great year-to-year variability in drift patterns is demonstrated. The results may explain some of the observed differences in recruitment between the main sandeel areas in the North Sea. In the northern sandeel area it seems that strong year classes are unlikely if the retention due to unfavourable currents is poor, and that a high retention in the summer may favour a good year class. In the southern sandeel area no clear coupling between year class strength and larval drift is found, possibly because the retention always seems large enough for a potentially good year class. For more quantitative use of such models in relation to sandeel recruitment, more biological knowledge is obviously needed on larval vertical distribution and timing of sandeel hatching and settling.     

南美白对虾幼体和仔虾淀粉酶和脂肪酶活力的研究

以酶学分析方法测定了南美白对虾状幼体,糠虾和仔虾三个发育期淀粉酶和脂肪酶的活力。试验结果表明,糠虾期淀粉酶比活力显著高于状幼体和仔虾两期(P<0.05);脂肪酶比活力状幼体显著高于糠虾幼体(P<0.05)。在食性转化过程中,南美白对虾幼体消化酶活力与其食性相适应,不同发育阶段消化酶调节机制不同。     

Trypsin enzyme activity during larval development of Litopenaeus vannamei (Boone) fed on live feeds

Larval stages of the Pacific white shrimp, Litopenaeus vannamei (Boone) were fed standard live diets of mixed microalgae from the first to the third protozoea (PZ1 to PZ3), followed by Artemia nauplii until post‐larvae 1 (PL1). Trypsin enzyme activity for each larval stage was determined using N‐α‐p‐toluenesulphonyl‐l ‐arginine methyl ester (TAME) as a substrate. Results were expressed as enzyme content to assess ontogenetic changes during larval development. Tissue trypsin content (IU µg^?1 DW for each larval stage) was significantly highest at the PZ1 stage and declined through subsequent stages to PL1. This contrasts with previously observed patterns of trypsin development in Litopenaeus setiferus (Linnaeus) and other penaeid genera, which exhibit a peak in trypsin activity at the third protozoea/first mysis (PZ3/M1) larval stage. Litopenaeus vannamei larvae transferred to a diet of Artemia at the beginning of the second protozoea (PZ2) stage were significantly heavier on reaching the first mysis stage (M1) than those fed algae, while survival was not significantly different between treatments. At both PZ2 and PZ3 stages, trypsin content in larvae feeding on Artemia was significantly lower than in those feeding on algae. The rapid decline in trypsin content from PZ1 and the flexible enzyme response from PZ2 suggest that L. vannamei is physiologically adapted to transfer to a more carnivorous diet during the mid‐protozoeal stages.     

东海区拖虾渔业概况分析

虾类是东海区的主要捕捞对象之一。东海区的拖虾渔业以虾类为主要捕捞目标,发展之初对于促进捕捞结构调整、减轻主要经济鱼类的捕捞压力起了重要作用。但是随着该种作业方式生产规模的不断扩大、生产渔船和渔具的大型化,渔获物中经济虾类和兼捕幼虾的矛盾日益突出,对东海区的渔业资源造成较大程度的破环。本文主要介绍了东海区拖虾渔业的发展和资源概况,主要经济虾类的种类、分布、作业渔船的产量和数量变化,分析了东海区拖虾渔业中存在的问题和所采取的措施,并提出了解决问题的建议。     

Artemia enriched with high n-3 HUFA may give a large improvement in performance of Atlantic halibut (Hippoglossus hippoglossus L.) larvae

Atlantic halibut larvae were fed Artemia enriched with two different oil emulsions (cod liver oil and 2050TG) from first feeding to 70 days after first-feeding (dpff). Larvae fed 2050TG enriched Artemia had better growth, survival and eye migration than larvae fed the cod liver oil enriched Artemia, while pigmentation rate was similar in the two groups. In addition to the difference in fatty acids, the two emulsions differed in lipid class composition, since 2050TG is a synthetic oil and a mixture of mono-, di- and tri-acylglycerol, while cod liver oil is a tri-acylglycerol. Total lipid level, estimated as fatty acid methyl esters (FAME) was similar in the two Artemia types, but sum of n-6 and n-3 fatty acids, arachidonic acid (20:4n-6, ARA), docosahexaenoic acid (22:6n-3, DHA) and eicosapentaenoic acid (20:5n-3, EPA) were higher in Artemia enriched with 2050TG than in the cod liver oil enriched Artemia. However, the main difference in fatty acid composition in the larvae, was a higher DHA (% of total fatty acids) in 2050TG larvae than in cod liver oil larvae. The lipid level measured as FAME was up to four times higher in the 2050TG larvae than in the cod liver oil larvae, and the reason for this may have been a better bioavailability of the partly digested lipid in the 2050TG emulsion. The correlation between a high level of lipid in the larval tissues (e.g. high energy status) and improved eye migration in larvae fed the 2050TG enriched Artemia supports the hypothesis that energy limitation on the larval stage may be a cause of the impaired eye migration commonly observed in farmed Atlantic halibut juveniles.     

饵料蛋白能量比对黑鲷幼鱼生长和体成分的影响

取黑鲷(Sparusmacrocephalus)幼鱼960尾,体重(3.39±0.18)g,以鱼粉和豆粕作为蛋白源,鱼油和豆油等比例混合油作为脂肪源,共配制4个蛋白水平(34%、38%、42%、46%),每一蛋白水平设3个脂肪水平(10%、13%、16%),共12种饵料,糖水平保持在16%左右,饵料的蛋白能量比(P/E)在96.76～136.21mg/kcal。黑鲷幼鱼随机分成12组,每组设2重复,实验为期42d。结果表明,对特定生长率(SGR)与饵料系数(FCR)的影响,以较高蛋白组(38%、42%、46%)显著优于低蛋白组(34%)(P<0.05),中、高脂肪组(13%、16%)显著优于低脂肪组(10%)(P<0.05);各组饵料对成活率的影响无显著差异(P>0.05)。当蛋白水平为42%,脂肪水平为16%时,黑鲷幼鱼获得最大特定生长率(3.20)、最高蛋白质效率(2.10)和最小饵料系数(1.14)。全鱼脂肪含量随着饵料中脂肪水平的提高而逐渐升高。在同一饵料蛋白水平内,全鱼蛋白与灰分含量随着饵料脂肪水平的提高呈逐渐升高趋势。经统计分析,饵料中不同蛋白能量比显著影响黑鲷幼鱼生长(P<0.05),饵料中脂肪有明显节约蛋白质的作用(P<0.05)。由生长及体成分的实验结果得出,黑鲷幼鱼的最适饵料蛋白水平为42%,最适蛋白能量比(P/E)为110.37mg/kcal。