陆基高密度循环水养殖的水质调控技术

利用先进的工厂化水产养殖技术与设施进行的全封闭高密度循环水养殖，具有节水、节地、节能、环保等优点。其成功的关键在于对养殖水体的水质调控。以下就陆基水产养殖的水质调控技术作一介绍。     

Effects of Biofilter/Culture Tank Volume Ratios on Productivity of a Recirculating Fish/Vegetable Co-Culture System

Abstract

The effects of four biofilter volume (BFV)/culture tank volume ratios (0.67/1, 1.00/1, 1.50/1, and 2.25/1) on biofilter function were examined in a recirculating fish/vegetable production system in a greenhouse. Sand beds served as biofilters, as substrate for vegetable growth, and as location for decomposition of waste solids. No fertilizer was used. Three experiments were conducted over the course of one year. In Experiment 1, as the BF V/tank volume ratio increased, total ammoniacal nitrogen (TAN) and nitrite concentrations decreased (9.0 to 3.6 mg/L and 0.39 to 0.20 mg/L, respectively), and biomass increase over the culture period and oxygen levels increased significantly (13.34 to 16.03 kg/m³ and 6.03 to 6.47 mg/L, respectively). pH was maintained at 5.8-6.2 without the addition of lime. Yield per plant of the tomato variety ‘Laura’ tended to decrease (3.4 to 2.3 kg/plant), and yield per plot increased (13.6 to 31.6 kg/plant) with increasing BFV/tank ratio. In Experiment 2, the system was operated for 42 days without plants. pH dropped rapidly to near 4.0. Cucumbers were then planted, and weekly additions of lime and CaO were made. Significantly less CaO was required to achieve target pH in systems with the largest BFV/tank ratios. pH levels conducive to good plant growth were only slowly stabilized, and cucumber yields were erratic. TAN and nitrite levels were not measured, but fish grew well (5.2 to 7.2 kg/m³ with increasing BFV/tank ratio). By Experiment 3, with the tomato variety ‘Kewalo,’ TAN and nitrite concentrations decreased from 0.96 to 0.48 mg/L and from 0.06 to 0.02 mg/L, respectively, with increasing BFV/tank ratio, and in the latter part of the experiment, pH was stabilized at 6.3-6.5 without lime. Yield/plant decreased from 5.0 to 2.4 kg/plant and yield per plot increased from 19.9 to 33.1 kg/plot with increasing BFV/tank ratio. Daily water exchanges averaged 2.8%. Nutrient concentrations of the irrigation water after a year's operation were low overall. Although plants showed no deficiency or toxicity symptoms, K⁺ was found to be low and Zn⁺⁺ high relative to other ions. No clogging was observed in the sand beds. Carbon measurements ± SEM of the sand medium at the wastewater inlet of the smallest and largest BFV/tank ratio systems were 0.23 ±0.03%, and 0.15 ±0.01%, respectively. Nitrogen was below detectable levels (<0.04%). The enhanced biofil-ter/culture tank ratios used here resulted in a functionally well balanced fish/vegetable co-culture system. While needing refinement, this design represents a step towards a highly productive, low-tech system with efficient use of water, chemical, and labor resources.     

冷水性鱼类循环水养殖系统设计及养殖虹鳟试验研究

本文论述了冷水性鱼类循环水养殖工艺、设施与装备系统的设计研究,该研究进行了虹鳟鱼养殖试验,突破了养殖水体氨氮低温处理技术关键,形成了低温微生物驯化处理和臭氧催化氧化处理新方法,建立了节约水资源、减少污染的封闭循环式养殖系统集成技术。试验表明,在空气增氧的条件下,冷水性鱼类循环水养殖,养殖密度达到38kg/m3,各项水质指标符合鱼类正常生长要求。     

Growth and Feed Utilization of Captive Wild Black Sea Bass Centropristis striata at Four Different Densities in a Recirculating Tank System

A study to determine the effects of four stocking densities on growth and feed utilization of wild‐caught black sea bass Centropristis striata was conducted in a pilot‐scale recirculating tank system. The outdoor system consisted of 12 insulated fiberglass tanks (dia. = 1.85 m; vol. = 2.17 m³) supported by biological filters, UV sterilizers, and heat pumps. Subadults (N= 525; ×± SD = 249 ± 16.8 g) were stocked at densities of 4.6 fish/m³ (1.18 kg/m³), 16 fish/ m³ (3.91 kg/m³), 25.3 fish/m³ (6.83 kg/m³), and 36 fish/m³ (7.95 kg1m³), with three replicate tanks per treatment. Fish were grown under 35 ppt salinity, 21‐25 C, and under ambient photoperiod conditions. A commercial flounder diet containing 50% protein and 12% lipid was hand‐fed twice daily to satiation for 201 d. Mean (range) total ammonia‐nitrogen, 0.61 (0‐2.1) mg/L, nitrite‐nitrogen, 0.77 (0.04‐3.6) mg/L, and nitrate‐nitrogen 40.1 (0‐306) mg/L were significantly higher (P < 0.0001) in the 25.3 and 36 fish/m³ treatments than in the 4.6 and 16 fish/m³ treatments [0.19 (0.05‐0.5), 0.1 (0.24‐0.63), and 11.9 (1.3‐82.2) mg/L, respectively]. However, there were no significant differences (P > 0.05) in growth (RGR = 196.8‐243.1%; DWG = 2.55‐2.83 g/d; and SGR = 0.55‐0.61%/d), coefficient of variation of body weight (C_wtV., = 0.24‐0.25), condition factor (K = 2.2‐2.4), feed consumption (FC = 1.45‐1.65%/d), and feed conversion ratio (FCR = 1.45‐1.52) among stocking densities. Final biomass densities on day 201 reached 3.48, 12.0, 21.1, and 27.2 kg/m³ at stocking densities of 4.6, 16, 25.3, and 36 fish/m³, respectively. Survival (83.8‐99.1%) did not differ among treatments. Apparent net protein retention (ANPR) was significantly higher (P < 0.005) for fish stocked at the lower densities of 4.6 and 16 fish/m3 (22.5‐23.7%) than for those stocked at 25.3 and 36 fish/m³ (21‐20.1%). There were no significant differences (P > 0.05) in apparent net energy retention (ANER = 55.9‐59.1 %) among stocking densities. Final whole body protein (15.3‐16.3%) and lipid (23.1‐26.4%) levels did not differ significantly (P > 0.05) among treatments. The results demonstrated that growth, survival, and feed utilization were not impaired under stocking densities ranging from 4.6‐36 fish/m³ (3.48‐27.2 kg/m3), despite a slight reduction in water quality at the higher densities. In addition, growth variation and final whole body protein and lipid levels were not influenced by these densities. The results suggest that black sea bass are tolerant of crowding and moderate variations in water quality during intensive culture in recirculating tank systems and that higher stocking densities are possible.     

Effects of Different Feed Habituation Methods on Survival and Feed Habituation Success of Largemouth Bass,Micropterus salmoides,in a Recirculating Aquaculture System

Demand for food size and trophy largemouth bass, Micropterus salmoides, is steadily increasing. However, largemouth bass, a carnivorous species, are more difficult to feed habituate than other commercially produced fish. Improving current feed habituation techniques to increase the percentage of fingerlings successfully feed habituated would increase profits, productivity and efficiency, and available product in the largemouth bass industry. The focus of this research was to evaluate different combinations of automatic feeders and supplemental hand feeding to determine the feed habituation success under commercial largemouth bass production conditions. Hand feeding, using only automatic feeders, or combinations of both, did not result in significant differences with regard to survival or feed habituation success. Initial fingerling size (total length, TL) was found to be the most important factor affecting survival and feed habituation success. Fish ranging from 40 to 50 mm (TL) survived and feed habituated at significantly higher rates than 30–40 and 50–60 mm (TL) fingerlings. Medium‐sized fish provide the best results in terms of feed habituation success and survival. The results suggest any combination of hand feeding and automatic feeders may be used to achieve feed habituating success in largemouth bass.     

气/水混合溶解机在封闭式循环养殖系统中的应用试验

在封闭式循环养殖系统中,采用气／水混合溶解机调节虹鳟养殖水中的溶氧量。设置4种溶氧量,分别为7．05、8．82、11．84、15．80mg／L,其中8．82mg／L为对照组,充空气;试验30d,对虹鳟幼鱼（体长13．0—18．5em）的生长率、能量收支及机体的营养组成进行研究。试验结果表明,7．05mg／L的低溶氧组鱼在生长率和饲料转化效率方面均明显低于对照组（P〈0．05）,而11．84mg／L和15．80mg／L的高氧组鱼食物转化效率高,生长率明显提高。由摄食能的分配结果可见,随着溶解氧的升高,虹鳟幼鱼的摄食能用于生长和代谢的比例提高。表明在封闭式循环养殖系统中高溶解氧对虹鳟幼鱼生长具有良好的促进作用。     

Pilot Production of Hatchery-Reared Summer Flounder Paralichthys dentatus in a Marine Recirculating Aquaculture System: The Effects of Ration Level on Growth, Feed Conversion, and Survival

Pilot‐scale trials were conducted to evaluate growout performance of hatchery‐reared summer flounder fingerlings in a state‐of‐the‐art recirculating aquaculture system (RAS). The outdoor RAS consisted of four 4.57‐m dia × 0.69‐m deep (vol. =11.3 m³) covered, insulated tanks and associated water treatment components. Fingerlings (85.1 g mean initial weight) supplied by a commercial hatchery were stocked into two tanks at a density of 1,014 fish/tank (7.63 kg/m³). Fish were fed an extruded dry floating diet consisting of 50% protein and 12% lipid. The temperature was maintained between 20 C and 23 C and the salinity was 34 ppt. Under these conditions, growth, growth variation (CV_wt), feed utilization, and survival of fish fed to 100% and 82% of a satiation rate were compared. Due to clear changes in growth patterns during the study, data was analyzed in three phases. During phase 1 (d 1–d 196), fish showed rapid growth, reaching a mean weight of 288 g ± 105 and 316 g ± 102, with a CV_wt of 0.36 and 0.32 and FCR's of 1.38 and 1.36 in the subsatiation and satiation groups, respectively. During phase 2 (d 196–d 454), fish displayed slower growth reaching mean weights of 392 g ± 144 and 436 g ± 121, with a CV_wt of 0.37 and 0.28, and increasing FCR's of 3.45 and 3.12 in the subsatiation and satiation groups, respectively. During phase 3 (d 454–d 614), fish showed little growth reaching mean weights of 399 g ± 153 and 440 g ± 129, with a CV_wt of 0.38 and 0.29 in the subsatiation and satiation groups, respectively. Over the entire growout period (d 1–d 614), feed conversion ratios were 2.39 and 2.37 and survival was 75% and 81 % in the subsatiation and satiation treatments, respectively. The maximum biomass density reached during the study was 32.3 kg/m³. The satiation feed rate was superior to the 82% satiation rate, since it maximized growth rates, with no effect on FCR. The higher CV_wt in the subsatiation group suggests increased competition for a restricted ration led to a slower growth with more growth variation. The decrease in growth in phases 2 and 3 was probably related to a high percentage of slower growing male fish in the population and the onset of sexual maturity. This study demonstrated that under commercial scale conditions, summer flounder can be successfully grown to a marketable size in a recirculating aquaculture system. Based on these results, it is recommended that a farmer feed at a satiation rate to minimize growout time. More research is needed to maintain high growth rates through marketable sizes through all‐female production and/or inhibition of sexual maturity.     

Growth and Feed Utilization of Captive Wild Subadult Black Sea Bass Centropristis striata Fed Practical Diets in a Recirculating System

The effects of four practical diets on growth, feed utilization, and body composition of wild‐caught juvenile and subadult black sea bass Centropristis striata (316 ± 113 g =±± SD) were compared for 221 d in a recirculating tank system consisting of 12 2,660‐L tanks. Salinity averaged 33.5 ppt and temperature averaged 20.9 C but vaned from 12 to 27.1 C. Diets differed in crude protein (CP) and crude lipid (CL) as follows: 1) low CP (44.0%), low CL (11.4%) trout diet; 2) low CP (44.8%), high CL (15.0%) trout diet; 3) midlevel CP (47.9%), midlevel CL (12.8%) Bounder diet; and 4) high CP (53.9%), high CL (15.1%) marine finfish diet. Energy: protein ratios (E: P) were 44.6, 45.3, 41.8, and 39.1 W/g. Survival to 221 d on all diets was 100%. Significant (P < 0.05) differences in growth rates were observed among diets. Final weights were higher for midlevel and high CP diets 3 and 4 (1,051 and 1,013 g) than for low CP diet 1 (873 g). Relative growth rate (RGR, % total increase in weight), specific growth rate (SGR, % increase in body weight/d), and daily weight gain (DWG, g/d) were higher for higher CP diets 3 and 4 (RGR = 223 and 221; SGR = 0.53; DWG = 3.28 and 3.16), than for low CP diet 1 (RGR = 181; SGR = 0.47; DWG = 2.54). There were no significant differences between initial and final whole body protein and fiber content among diets. Lipid and gross energy levels significantly increased (P < 0.0001) in all treatments while moisture levels significantly decreased (P < 0.001). Although these differences were not significant, feed conversion ratio (FCR = dry weight fed/wet weight gain) was lower for fish given midlevel CP diet 3 (1.49) and high CP diet 4 (1.52) than for those fed low CP diets 1 and 2 (1.60 and 1.62). Protein efficiency ratios (PER = weight gain/weight protein fed) (1.43 to 1.24), apparent net protein retention (ANPR = weight protein gain/weight protein fed) (20 to 25%), and apparent net energy retention (ANER = energy gain/energy fed) (53.3 to 56.8%) were not significantly different among treatments. The midlevel CP (50%), midlevel CL (12%) diet maximized growth rates and was also significantly less expensive per kg fish weight produced ($1.40) than the high CP diet ($1.94) which produced the second highest growth rates. These results demonstrated that wild‐caught black sea bass can be successfully reared in recirculating tanks from juvenile to marketable sizes with high survival and with good feed conversion and growth on commercially prepared diets with a wide range of protein and lipid levels.     

多级生物净化在封闭循环水养殖系统中的水质调控效果

采用逐月采样的方法研究了多级生物净化措施,即在封闭循环水养殖系统的动力水渠浮床培植多种水生经济植物、构建固定微生物膜和养殖贝类,在沉淀池和净化池放养滤食性鱼类,建立芦苇人工湿地,对养殖系统中无机营养盐和有机质含量与分布的影响。试验结果表明,养殖水体经多级生物净化处理后能够循环使用,水体碱度和硬度轻微降低,除磷酸盐含量上升5.4%外,硝态氮、亚硝态氮、氨氮、总氮和总磷的去除率分别为27.7%、44.0%、26.0%、42.0%和15.7%;浮游植物和浮游动物生物量分别下降31.4%和20.1%;浮游植物生物多样性指数增加,种类组成明显好转,蓝藻生物量和优势度指数明显降低,硅藻和绿藻继而成为优势种群,凡纳滨对虾平均产量达11 250kg/hm~2,最高产量达15 000kg/hm~2,提高了经济效益和生态效益。     

Stocking Density for Nursery Production of Redclaw Crayfish,Cherax quadricarinatus,in a Recirculating System

Redclaw crayfish, Cherax quadricarinatus, early juveniles were reared at different stocking densities in a closed recirculation system using 12-L plastic containers as rearing tanks. Initial stocking densities were 1.0, 1.5, 2.0, 2.5, and 3.0 per liter (66, 89, 111, 133, and 156 crayfish/m², respectively). Rearing period was 42 days. Each density was tested with five replicates. Shelter (0.112 m²) was added to double the surface area of rearing tanks. Animals were fed ad libitum twice a day with a commercial diet containing 35% crude protein. There were no significant differences (P < 0.05) in length and specific growth rate (SGR) among stocking densities. Final weight and daily weight gain, however, were significantly higher at the density of 66 per m² (1.0 per liter). Total biomass at harvest increased with density. Survival was affected by stocking density from day 28 onward, decreasing with density from 62.7 ± 7.6% obtained at 66 crayfish/m² to 44.85 ± 8.18% at 156 crayfish/m².     

Evaluation of Tilapia Effluent with Ion Supplementation for Marine Shrimp Production in a Recirculating Aquaculture System

Reuse of fish effluent for the culture of marine shrimp, such as Pacific white shrimp, Litopenaeus vannamei, could provide an opportunity for the US shrimp farming industry to ease constraints (e.g., environmental concerns and high production costs) that have limited them in the past. In this study under laboratory‐scale conditions, the feasibility of culturing L. vannamei in effluents derived from a commercial facility raising tilapia in recirculating aquaculture systems (RAS), supplemented with various salt combinations, was compared to the shrimp’s survival and growth in well water supplemented with 17.6 (control) and 0.6 (freshwater treatment) g/L synthetic sea salt. Three independent trials were conducted in RAS in which survival and growth in the control, the freshwater treatment, and two effluent treatments were compared. Water quality during this study was within safe levels and no differences (P < 0.05) between treatments were observed for dissolved oxygen, nitrite, pH, total ammonia nitrogen, and temperature. However, average nitrate and orthophosphate levels were consistently more than an order of magnitude greater in the effluent treatments compared to the control and the freshwater treatments. Survival and growth of shrimp over 6‐wk periods did not vary significantly between the control and the freshwater treatments; however, shrimp tested in the tilapia effluents often exhibited significant effects (P < 0.05) depending on the salts added. In the low‐salinity waters, correlations (P < 0.05) were observed between Ca²⁺, Mg²⁺, Ca²⁺ and Mg²⁺, K⁺, Na⁺ : K⁺ and Ca²⁺ : K⁺, and shrimp survival and growth. The results of this study revealed that L. vannamei can be raised in tilapia effluent when supplemented with synthetic sea salt (0.6 g/L), CaO (50 mg/L Ca²⁺), and MgSO₄ (30 mg/L Mg²⁺).     

An Analysis of Biological, Economic, and Engineering Factors Affecting the Cost of Fish Production in Recirculating Aquaculture Systems

Aquaculture production in recirculating systems has been the focus of research and development efforts for decades. Although considerable resources have been expended on these systems in the private sector, there is a scarcity of data on the economic or engineering performance of commercial scale recirculating production systems. This paper presents the results of a computer simulation of tilapia production in a small recirculating production system. Much of the performance data has been developed at a demonstration facility at North Carolina State University. Given the assumptions of the base case simulation, the cost of producing a kilogram of tilapia in the recirculating system described is estimated to be $2.79 ($1.27/lb). The results of a model sensitivity analysis indicate that while improvements in the performance efficiency of system components did not greatly affect fish production costs, reductions in feed costs and improvements in the feed conversion ratio caused the greatest reduction of production cost of all of the operational variables investigated. The analysis further indicates that the greatest gains to be realized in improving profitability are those associated with increasing the productive capacity or decreasing the investment cost of a recirculating fish production system.     

Using Genetic Variation to Understand Control of Feed Intake in Fish

The overall goal of our research is to develop fish with superior growth, and feed efficiency attributes. Feed intake is integral to these characters. Over the last several years we have been working with channel catfish, Ictalurus punctatus, in two directions tied to feed intake regulation. One direction has been to identify genes functioning as physiological regulators of feed intake, and the other has been to measure and characterize the genetic variation in feed intake within and among distinct catfish populations which reveal a wide range in feeding response. The goals are to uncover the genetic basis of physiological variation, to understand the genes and interactions that produce the phenotypic differences observed and to exploit these differences in a selective breeding program. To investigate the links between genetic variation and physiological variation, differences in voluntary feed consumption were documented in two strains of channel catfish. Treatment with orexigenic compounds affected both strains similarly, though anorexigenic compounds inhibited feeding in one strain more than the other and low temperature treatment affected the strains differently with respect to feed efficiency. Phenotypic variation in feed intake among families within one strain suggested that approximately 40% of the variation in feed intake is due to genetic sources. Future work aimed at utilizing strains and families with divergent phenotypes for identifying the specific genes responsible for this variation is discussed.     

Effects of Stocking Density and Monosex Culture of Freshwater Prawn Macrobrachium rosenbergii on Growth and Production in Concrete Tanks in Saudi Arabia

Abstract This study was conducted to evaluate the effects of stocking density and monosex culture on growth, survival, yield and feed conversion ratio of freshwater prawn Macrobrachium rosenbergii in concrete tanks. Juvenile prawns with an average weight of 1.8 g were stocked into triplicate tanks at densities of 5, 10, 15 and 20 prawns/m², grown for 168 d and fed a 34% tilapia diet. Stocking density had significant effect on prawns. Final mean body weight decreased with the increasing density, being highest at 5 prawns/m² (29.6 9). and lowest at 20 prawns/m² (17.4 g). Total yield increased from 135 g/m² (1,350 kg/ha) at a density of 5 prawns/m² to 261 g/m² (2,610 kg/ha) at density 15/m^z to 245 g/m² (2,450 kg/ha) at 20/m^z. Feed conversion ratios were high and ranged from 3.7 (5 prawns/m²) to 5.6 (20 prawns/m²).
In monosex culture of freshwater prawns stocked in triplicate tanks at a density of 5 prawns/m² for 112 d, the all-male population had the best growth performance and feed conversion ratio, followed by the mixed-sex and all-female populations. The all-male population had 99% marketable prawns (>20 g) with an average yield of 159 g/m² (1,590 kg/ha); the mixed-sex population had 90% marketable prawns and the yield was 135 g/m^z (1,350 kg/ha); and the all-female population had 75% marketable prawns with an average yield of 108 g/m² (1,080 kgha).     

河蟹工厂化育苗中人工半咸水的净化与循环利用

采用室内，室外大循环的水交换形式及生物净化和物理，化学处理相结合的方法，对河蟹育苗废水进行净化与循环利用，可将育苗用人工半咸水的利用率提高２－３倍，节约配水原料５０％。另外把育苗废水的生物净化与单胞藻，轮虫的培养结合在一起，既可净化水质，又能为蟹苗提供大量的生物饵料，试验池蟹苗的成活率较对照池提高１．０－２．５％。     

Tolerance to Formalin by a Fluidized-Bed Biofilter and Rainbow Trout Oncorhynchus mykiss in a Recirculating Culture System

Formalin tolerances of a fluidized-bed sand biofilter and rainbow trout Oncorhynchus mykiss were tested in a semi-closed freshwater recirculating culture system. Progressively higher formalin levels were tested until fish mortality (±1.9%) occurred. A 1-h exposure to 167 ppm formalin, followed by flushing, was safe for trout (no mortality) at 15.0 C but not at 16.5 C. A 110-ppm indefinite treatment (no flushing) was safe at 17.3 C, but 120 ppm at 17.3 C and 100 ppm at 17.8 C were not. Biofilter nitrification was not impaired by 1-h formdin treatments up to 167 ppm at 16.5 C, and not, usually, by indefinite treatments up to 120 ppm at 17.3 C. However, a find indefinite treatment of 70 ppm was followed by abnormally high nitrite levels for 9 d. Formaldehyde remained detectable in the system for 11 h during indefinite treatment at 120 ppm formalin. Tests on the system's Co₂ stripper did not indicate that it removed formaldehyde.     

Molecular Screening and Biocontrol of Aflatoxigenic Fungi in Fish Feed

ABSTRACT

Contamination of fish feed (FF) with aflatoxigenic fungi is an ongoing hazardous risk and is the first route for transferring aflatoxins to consumers from fish products. Prevention is the gold standard to deal with microbial food contamination. Different FF samples (n = 38) were screened for the occurrence of fungal contamination, and identified Aspergillus flavus isolates were assessed for the presence of aflatoxigenic production genes (Nor-1, Ver-1, and Omt-A) and the ability to produce aflatoxins. Biocontrol of aflatoxigenic A. flavus was proposed via exposure to plant (Cinnamon bark, Athl, and Lilac leaves) smoldering fumes (PSF). Numerous fungal species were identified from FF; Aspergillus spp. was the prevalent genus, followed by Penicillium spp. and Fusarium spp. The complete set of aflatoxigenic genes was detected in 54.8% of A. flavus isolates and was correlated with their aflatoxin-producing ability. The PSF exposure was successful for inhibiting A. flavus growth in agar media and in contaminated fish feed. Cinnamon PSF was the most effective and could entirely inhibit fungal growth at a proportion of 20 g/m³ in both treatments. The PSF exposures could be suggested as effectual techniques for complete biocontrol of aflatoxigenic fungi in fish feed to protect fish and consumers from their threatening effects.     

云南境内南盘江水系鱼类种质资源现状及保护对策

为了解南盘江鱼类资源现状,保护和恢复南盘江鱼类多样性,2008年6月至2010年3月,对云南省境内南盘江鱼类现状进行实地考察,结合中国科学院昆明动物研究所馆藏标本和历年相关记录,分析南盘江鱼类种质资源现状。结果表明,云南境内南盘江及其附属湖泊共有鱼类8目、20科、71属、160种;其中,土著种137种,特有种93种,外来种23种。鲤科鱼类最多,有94种,占鱼类总数的58.8%,其次为条鳅科32种,占总数的20.0%,爬鳅科7种,占总数的4.4%。南盘江鱼类种类众多,但由于人为影响,河流污染比较严重,目前已有24种鱼类被列为濒危种类。分析南盘江近两年的鱼类种质资源现状,发现土著种类的数量大幅下降,这与南盘江河流环境恶化和水电开发力度增大密切相关。     

Production Characteristics, Water Quality, and Costs of Producing Channel Catfish Ictalurus punctatus at Different Stocking Densities in Single-batch Production

Channel catfish Ictalurus punctatus farming is the largest component of aquaculture in the USA. Culture technologies have evolved over time, and little recent work has been conducted on the effects of stocking density on production characteristics and water quality. Twelve 0.1‐ha ponds were stocked with 13‐ to 15‐cm fingerlings (16 g) at either 8600, 17,300, 26,000, or 34,600 fish/ha in single‐batch culture with three replicates per treatment. Fish were fed daily to apparent satiation with a 32% floating commercial catfish feed. Nitrite‐N, nitrate‐N, total ammonia nitrogen (TAN), total nitrogen, total phosphorus, chemical oxygen demand (COD), Secchi disk visibility, chlorophyll a, chloride, total alkalinity, total hardness, pH, temperature, and dissolved oxygen (DO) were monitored. Ponds were harvested after a 201‐d culture period (March 26, 2003 to October 13, 2003). Net yield increased significantly (P < 0.05) as stocking density increased, reaching an average of 9026 kg/ha at the highest density. Growth and marketable yield (>0.57 kg) decreased with increasing stocking density. Survival was not significantly different among densities. Mean and maximum daily feeding rates increased with density, but feed conversion ratios did not differ significantly among treatments (overall average of 1.42), despite the fact that at the higher stocking densities, the feeding rates sometimes exceeded 112 kg/ha per d (100 lb/ac per d). Morning DO concentrations fell below 3 mg/L only once in a 34,600 fish/ha pond. Concentrations of chlorophyll a, COD, nitrite‐N, and TAN increased nominally with increasing feed quantities but did not reach levels considered problematic even at the highest stocking densities. Breakeven prices were lowest for the highest stocking density even after accounting for the additional time and growth required for submarketable fish to reach market size. While total costs were higher for the higher density treatments, the relatively higher yields more than compensated for higher costs.     

云南境内南盘江水系鱼类种质资源现状及保护对策

为了解南盘江鱼类资源现状,保护和恢复南盘江鱼类多样性,2008年6月至2010年3月,对云南省境内南盘江鱼类现状进行实地考察,结合中国科学院昆明动物研究所馆藏标本和历年相关记录,分析南盘江鱼类种质资源现状。结果表明,云南境内南盘江及其附属湖泊共有鱼类8目、20科、71属、160种;其中,土著种137种,特有种93种,外来种23种。鲤科鱼类最多,有94种,占鱼类总数的58.8%,其次为条鳅科32种,占总数的20.0%,爬鳅科7种,占总数的4.4%。南盘江鱼类种类众多,但由于人为影响,河流污染比较严重,目前已有24种鱼类被列为濒危种类。分析南盘江近两年的鱼类种质资源现状,发现土著种类的数量大幅下降,这与南盘江河流环境恶化和水电开发力度增大密切相关。