无效负载率的概念和水库鱼产力的推算

影响水库鱼产力的主要因素可分为两个方面:一是营养元素丰度、初级生产力大小和饵料生物多寡;二是鱼类区系组成和鱼类种群的年龄结构。我国以往的研究工作主要是根据初级生产力或浮游生物量及其P/ B系数对鱼产力进行估算。但我国大部分水库鲢和鳙的产量     

渭河流域陕西段典型水库鱼产力及鲢、鳙放养量估算

于2014年6-8月对渭河流域陕西段4座水库的浮游生物和初级生产力进行了调查,根据调查结果测算了各个水库的鱼产力和鲢鳙放养量。结果显示,4座水库浮游植物种类共鉴定出8门40种属,密度为12.00×10~4~132.50×10~4个/L,生物量为0.394 4~2.767 0mg/L;浮游动物的密度为50~2 180个/L,生物量为0.205 7~1.852 0mg/L;初级生产力(水柱平均日毛生产量)为0.405 3~2.206 5mg(O_2)/(m~2·d)。基于浮游生物的鱼产力为鲢鱼32.55~230.70kg/hm~2,鳙鱼46.28~231.60kg/hm~2;基于初级生产力计算的鲢鱼产力为26.23~142.28kg/hm~2,鳙鱼为14.75~80.31kg/hm~2。各个水库鲢鳙的合理放养量分别为98.13~621.63kg/hm~2、48.83~249.54kg/hm~2。     

辽宁省水库鲢鳙鱼产力的评估↑（*）

本文在对辽宁５８座水库调查的基础上，根据Ｆｕｚｙ聚类分析和逐步回归筛选的结果，采取了国内外实践证明效果较好和比较流行的评估鱼产力的模型，以现实连续五年的最高渔获量和浮游生物数据作为自变量，计算了其间的相关显著程度。认为形态土壤学指数（ＭＥＩ）效果最佳；形态流域指数（ＭＤＩ）在水库交换率大的地区使用时，应当增加径流深度与ＭＤＩ组成复回归分析。本文用形态土壤学指数和浮游生物两个变量，以吉林省高产的海龙水库对比，求出４３座水库可能达到的鱼产量。高产量达１００ｋｔ／ｋｍ２，低产者亦在１０ｔ／ｋｍ２以上。     

报刊要闻

<正> 水库鲢鳙鱼产力的评估 本文在对辽宁58座水库调查的基础上,根据Fuzzy聚类分析和逐步回归筛选的结果,采取了国内外实践证明效果较好和比较流行的评估鱼产力的模型,以现实连续五年的最高渔获量和浮游生物数据作为自变量,计算了其间的相关显著程度。认为形态土壤学指数(MEI)效果最佳;形态流域指数(MDI)在水库交     

新疆蘑菇湖水库浮游生物种群结构及鲢鳙鱼产力的研究

2016年4月(丰水期)、7月(平水期)和11月(枯水期)于水体上(距水面0.5m)、中、底(距水底0.5m)层分别采等量水混匀,调查新疆蘑菇湖水库的理化因子状况及浮游生物的种群结构,综合评价水库水质营养状况,并根据浮游生物现存量估算滤食性鲢鳙的鱼产力,以期通过合理放养鲢鳙降低水库过量氮磷含量,达到生态治理的目的。结果显示:采样期间蘑菇湖水库平均pH为8.33、平均水深4.55m、总磷含量0.29mg/L、氨氮含量4.94mg/L,水质为富营养型水库;共鉴定浮游植物90种,浮游动物36种,平均生物量分别为6.72mg/L和3.79mg/L,鱼产力分别为鲢468.18t和鳙720.13t。鲢和鳙的理论合理最大放养量分别为27.41万尾和70.33万尾,鲢∶鳙比例约为1∶2.57。     

水库渔获量与环境因素的多元回归模型

建国以来，全国共兴建水库86，000多座，养鱼面积达3，000万亩。为了充分发挥水库的渔业生产潜力，不少同志从资源利用、放养效益、浮游生物与鱼产力关系等方面探索了水库的渔业生产力。本文试图从水库渔获量与环境因素的关系出发，应用线性全回归模型、秩相关模型和对数偏相关模型等三种不同的方法，建立渔获量与环境的多元回归方程，     

孟家段水库饵料动物与鳙、鲤和鲫的鱼产力

报道了孟家段水库饵料动物资源状况,并据此推算了以动物为主要食物的鳙鱼、鲤鱼、鲫鱼的鱼产力。指出该水库平均鱼产力;鳙鱼为82kg/hm~2,鲤鲫鱼为10.7kg/hm~2。     

桃林口水库鱼产力评价

根据桃林口水库浮游植物、浮游动物、底栖动物、着生藻类、水生维管束植物等鱼类基础饵料生物平均生物量和有机碎屑有机碳平均含量计算得出桃林口水库鱼产力为1 377.82t,单位鱼产力为55.11t/km2。桃林口水库鱼产力高有水库新建、鱼种无法自然繁殖、渔业管理无序和鱼种投放不足四方面原因。     

孟家段水库饵料植物与鲢、草鱼鱼产力

报道子孟家段水库铒料植资源状况，并据此推算了植食性鱼鲢、草鱼的鱼产力。该水库鲢平均鱼产力为85kg/hm^2，草鱼仅在下库形成产量，鱼产力为57kg/hm^2。     

浮游生物完整性指数在浙江水源地水质评价中的应用

2009年9月和2010年8月依次对浙江省4座大中型水库水源地的浮游生物现状进行了调查,采用浮游生物完整性指数(P-IBI)评价方法对数据进行统计分析。经过对22个备选参数的筛选,构建了以藻类密度、藻类平均体重、藻类生物多样性指数、浮游动物/浮游植物、潜在产毒藻类丰度、不可食藻类密度比为入选参数的浮游生物完整性评价体系;进一步利用该评价体系对4座水库的水生态健康程度进行分级评价。结果表明,4座水库的P-IBI评价分值依次为1.216、5.157、3.304和3.542;P-IBI等级依次为差、优、良、良。评价结果能够较好地反映浙江省水源地的富营养化、藻类水华风险程度等水生态健康状况。     

Chronological age and reservoir characteristics as predictors of trait composition in Neotropical reservoir fish assemblages

One of the main impacts on aquatic environments is the alteration of flow regime, usually caused by dam construction. This impact changes the dynamics and functioning of the environment. We aimed to evaluate changes in the composition of functional traits of fish assemblages from 29 reservoirs of different chronological ages. We assessed if there were any alterations in trophic state of these reservoirs according to their ages (chronological variable). Then, we evaluated the relationship between functional traits and environmental/chronological variables. Results showed that reservoir age is a predictor of fish assemblage functional traits composition. In older reservoirs, there was a predominance of omnivorous species, with multiple spawning and parental care. However, herbivorous species, with total spawning and medium size, had their abundance reduced. Also, it was possible to identify the influence of depth and water retention time on the composition of functional traits. By showing that although age has an influence on composition, the intrinsic characteristics of each reservoir are very important in evaluating the impacts of these projects. Therefore, the findings presented provide insights into what may happen to functional traits of fish assemblages with ageing of reservoirs.     

Associations of fish with various types of littoral habitats in reservoirs

Fish associations with different types of littoral habitats were studied in four canyon‐shaped reservoirs in the Czech Republic in years 2010 and 2011 by gillnets. Two to three habitats per reservoir–beaches (former meadows), stump fields (former forest) and rubble slopes–were defined and sampled along the longitudinal axis of reservoirs. Effects of reservoir, habitat and locality (position along longitudinal axis) on fish biomass, abundance and species structure were tested for juvenile and adult fish separately. Hierarchical analysis of variance revealed that habitats differed significantly in fish biomass and abundance. Redundancy analysis showed that analysed environmental variables had significant influence on fish community structure. Most variability in community structure was explained by reservoir and then by combination of habitat and slope steepness. Locality position had the smallest influence on community structure. For both adult and juvenile fish total abundance and biomass, the most inhabited habitat was beaches; rubble slopes were the least inhabited. Habitat associations differed among species. Among adults, bream Abramis brama, white bream Blicca bjoerkna and roach Rutilus rutilus were associated with beaches and stump fields, whereas perch Perca fluviatilis, ruffe Gymnocephalus cernuus, asp Aspius aspius and pike Esox lucius were associated with rubble slopes. Bream, white bream, bleak Alburnus alburnus, roach, ruffe and pikeperch Sander lucioperca were associated with beaches among juveniles, whereas the only juvenile associated with rubble slopes was perch. We showed that most common species are associated with distinct habitats and also that utilisation of various littoral habitats differs in general.     

太泊湖浮游生物初步调查及鲢鳙鱼产力评估

2013年5、7、9和11月,对太泊湖浮游生物和水体状况开展了调查,评估了鲢鳙鱼产力。总碱度变化范围为62.92~89.09 mg/L;总氮、总磷及氨氮含量均严重超过地标水环境质量标准的Ⅱ类标准限值。共监测到浮游植物7门51属,平均密度1 593×104个/L,平均生物量20.166 mg/L;绿藻门、蓝藻门、硅藻门以及裸藻门为优势种群,生物量分别占浮游植物总生物量的24.3%、8.9%、16.2%和25.84%。共采集到浮游动物25种,其中原生动物5种、轮虫13种、枝角类5种、桡足类2种。浮游动物平均数量1 771.85个/L,平均生物量2.508 mg/L;枝角类、轮虫、原生动物、桡足类的生物量分别占总生物量的15.9%、78.7%、0.1%和35.2%,浮游动物多样性指数为0.36~0.46,均匀度指数为0.34~0.41。综合判断太泊湖处于富营养化状态。太泊湖鲢鱼产力151.2 kg/hm2,全湖约322 t;鳙鱼产力56.4 kg/hm2,全湖约120 t。     

The direct contribution of fish to lake phosphorus cycles

Abstract –  Published data are synthesised to assess the direct contribution of fish to the recycling of phosphorus across a lake productivity gradient. Phosphorus excretion rates by fish assemblages are more or less directly proportional to fish biomass, despite changes in mean body mass, species composition and diet with increasing lake productivity. Piecewise linear regression of published data shows for the first time that lacustrine fish biomass increases with total phosphorus (TP) concentration in the water column up to around 140  μ g·TP·l⁻¹ but levels off above that value, suggesting that fish contribute less to nutrient recycling as lake productivity increases. The results confirm previous findings that water column nutrient recycling by fish is much less important than by plankton and that fish are important nutrient stores in lakes. The contribution of fish to nutrient recycling is small because of their low turnover rates relative to other taxa.     

Primary productivity and related fish yield in intensely manured fishponds

Studies of various parameters associated with productivity were conducted in experimental manured ponds with the object of estimating the effects that organic manure produce on fish yield.Photosynthesis—depth profiles showed autoshading by the plankton resulting in compensation depths of approximately 70 cm. Net photosynthetic rates were found to be only slightly higher than those obtained under chemical fertilization. Their variation seemed to be somewhat independent of the total standing crop of plankton but was more directly related to the composition of the plankton.Several fish yield prediction models based on primary productivity were applied to the experimental data. In every case the results show that the actual yields considerably exceeded the predicted yields.This work gives support to the notion that primary productivity is not sufficient to account for the high fish yields attained in a manured system. Thus it is concluded that manuring of fishponds may not only be a practice of fertilization but also a means of promoting the growth of fish through some other alternative pathway.     

Yield predictive models for Sri Lankan reservoir fisheries

Tropical reservoirs are primarily constructed for irrigation, generation of hydroelectricity and water supply schemes. Development of inland fisheries is a secondary use of most reservoirs. In Sri Lanka, most reservoirs are scattered in the rural areas of the country so that investigation of the fisheries of individual reservoirs with a view to developing management plans is prohibitive. The present study was instigated to explore the possibilities of developing suitable yield predictive models, which can be used in developing management strategies for the Sri Lankan reservoirs. The study was carried out in 11 perennial reservoirs of Sri Lanka. Basic limnological parameters (conductivity, dissolved phosphorus, total phosphorus, chlorophyll a [chl a] content and alkalinity) were determined in each of these reservoirs. Daily data on fish catch and fishing effort were collected in each reservoir. Data on catchment areas (CA), reservoir area (RA) and reservoir capacity (RC) were obtained from the irrigation and survey departments. It is evident that chl a is positively influenced by nutrients (dissolved phosphorus and total phosphorus), morphoedaphic indices derived as alkalinity to mean depth (MEIa) and conductivity to mean depth (MEIc) ratios and CA/RC ratios. MEIa and MEIc are also positively influenced by CA/RC ratios. All these morphological and edaphic parameters were found to positively influence fish yield in reservoirs. As fishing intensity (FI) is also a major determinant of fish yields, fish yield was better accounted by multiple regression models in which FI and individual morphological and edaphic parameters were used as independent variables. Of these multiple regression relationships, the best predictive power for fish yield (Y in kg ha?1 yr?1) was found by Y=18.9+6.78 FI+0.0073 CA/RC where FI is expressed as boat‐days ha?1 yr?1 and CA and RC are in km2 and km3, respectively. In this relationship, FI and CA/RC account for about 68% of the variation in fish yield.     

The culture-based fisheries in small, farmer-managed reservoirs in two Provinces of northern Vietnam: an evaluation based on three production cycles

In this paper the results of a study conducted on the culture‐based fisheries in small (ranging from 2 to 160 ha), farmer‐managed reservoirs in YenBai and ThaiNguyen Provinces in the northern highland region of Vietnam, for the production cycles of 1997/98, 98/99 and 99/00 are presented. The small reservoirs are leased to small farmers by the provincial authorities for fishery activities, and all lessees adopt culture‐based fisheries when fingerlings of grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), common carp (Cyprinus carpio) and mrigal (Cirrihinus mrigala) are stocked between March and mid‐April each year and harvested, using large seine nets, after approximately 11–12 months. The mean yields from reservoirs in YenBai and ThaiNguyen Provinces in 97/98, 98/99 and 99/00 production cycles were 251, 332 and 253, and 331, 372 and 210 kg ha^?1 respectively. There were major differences in the fish productivity in the reservoirs in the two Provinces, and in a reservoir between culture cycles. The stocking strategies appeared to be rather ad hoc, being determined by the availability of seed stock and the financial status of the lessees. Accordingly, there was no apparent consistent trend in the improvement of yields from the culture‐based fishery practice throughout the growth cycles. The fish yields in reservoirs in each Province were significantly related to reservoir area (exponentially) and to mean weight of stocked fish and conductivity (logarithmically). Of the stocked fish, the highest returns were obtained with mrigal and bighead carp, which collectively contributed > 50% to the harvest. The return from common carp was the lowest. The mean growth rate of grass carp (2.7 g day^?1), followed by bighead carp (2.0 g day^?1) was the highest in reservoirs in YenBai Province, bighead carp (4.0 g day^?1) followed by grass carp (3.2 g day^?1) was the highest in ThaiNguyen Province. The seed stocked on average accounted for 65% and 48% of the total operating costs in YenBai and ThaiNguyen Provinces, and the mean cost:benefit ratio of the culture‐based fishery in the two Provinces was 0.35 and 0.37 respectively. The culture‐based fishery on average contributed about 28% to the gross income of a farmer lessee.     

Effects of recreational fishing on zooplankton communities of drainage system reservoirs at an open‐pit mine

The use of artificial water bodies for angling is a popular practice, especially in industrial and urbanised areas where natural water bodies are lost. In this study, the zooplankton structure dynamics and water quality at three strip mine drainage system reservoirs were assessed with different types of recreational fishery exploitation: K1—intensive angling using the catch‐and‐release model, K2—lowest angling pressure and higher share of predatory fishes and K3—moderate fishing, that is limiting groundbait quantities and eliminating non‐predatory fishes by anglers. The null hypothesis tested was that recreational fishing does not affect the biotic and abiotic conditions of reservoirs. The significance of each environmental variable was tested using redundancy analysis (RDA). The highest nutrients and chlorophyll a concentration, turbidity level and organic matter content occurred in K1. Zooplankton diversity was the lowest under these conditions; protozoa and larval stages of copepods dominated. In reservoirs where sustainable fishing was implemented (K2, K3), trophic parameters of water were lower, on average, by 25%, turbidity by 30%, and productivity by 35–70%. Zooplankton diversity was significantly higher; rotifers and small cladocerans dominated. The choice of recreational fishing model determines the functionality and biological potential of the reservoir.     

Evaluation of the robustness of predictive yield models based on catchment characteristics using GIS for reservoir fisheries in Sri Lanka

Land-use patterns in the catchment areas of Sri Lankan reservoirs, which were quantified using Geographical Information Systems (GIS), were used to develop quantitative models for yield prediction. The validity of these models was evaluated through the application to five reservoirs that were not used in the development of the models, and by comparing with the actual fish yield data of these reservoirs collected by an independent body. The robustness of the predictive models developed was tested by principal component analysis (PCA) on limnological characteristics, land-use patterns of the catchments and fish yields. The predicted fish yields in five Sri Lankan reservoirs, using the empirical models based on the ratios of forest cover and/or shrub cover to reservoir capacity or reservoir area were in close agreement with the observed fish yields. The scores of PCA ordination of productivity-related limnological parameters and those of land-use patterns were linearly related to fish yields. The relationship between the PCA scores of limnological characteristics and land-use types had the appropriate algebraic form, which substantiates the influence of the limnological factors and land-use types on reservoir fish yields. It is suggested that the relatively high predictive power of the models developed on the basis of GIS methodologies can be used for more accurate assessment of reservoir fisheries. The study supports the importance and the need for an integrated management strategy for the whole watershed to enhance fish yields.