异技麒麟菜对海水中氮、磷吸收的初步研究

在实验室条件下,设置四种不同营养盐浓度环境,分析异枝麒麟菜对氮、磷的去除效果。结果表明麒麟菜对海水中无机氮的去除率为89.5%～92.0%,对磷酸盐的去除率为79.6%～81.8%,对无机氮的吸收速率最高达到0.26μmol(/g·h),对磷酸盐的吸收速率最高达到0.009μmol(/g·h)。说明麒麟菜对氮、磷的吸收效果很明显,吸收速率随氮、磷浓度的升高而增大,对海水有很好的净化作用。     

Cultivation of the intertidal brown alga Hizikia fusiformis (Harvey) Okamura: mass production of zygote‐derived seedlings under commercial cultivation conditions,a case study experience

Mariculture of the brown alga Hizikia fusiformis (Harvey) Okamura as an export‐oriented human food has been there more for than 20 years in China. It is now one of the five major farmed algal species along the Chinese coast. Stable and sufficient supply of young seedlings for scaling up the cultivation has been a problem throughout the farming history of this species due to the unique dioecious life cycle and relatively short time window of sexual reproduction in nature. These two factors led to a practical difficulty in obtaining zygotes at identical developmental stage in viable amounts for seedling production. A key solution to this problem is to control the synchronization of the receptacle development and to realize the simultaneous discharge of male and female gametes, such that the fertilization rate could be greatly enhanced. Focusing on one of the farmed populations in this report, we present our results on mass production of seedlings using the synchronization technique on a large scale performed in 2007. Totally 5.5 hundred million embryos were obtained from 100 kg female sporophytes. The seedlings were raised up to 3.5 mm in length in greenhouse tanks over a month and were further grown in open sea for over 3 months at two experimental sites. The success of mass production of seedlings in this alga helped to lay the basis for future trials in other species in the genus of Sargassum that have identical life cycle.     

The Economics of Intensifying Catfish Production: A Production Function Analysis1

Yields of channel catfish in the United States have increased as a result of higher levels of stocking, feeding and aeration. A Cobb-Douglas production function was estimated using survey data from 66 catfish ponds in West-Central Alabama to determine if further intensification of catfish production in West-Central Alabama would be profitable. Feed, capital, stocking rate, and length of production period explained most of the variation in yield. Values of the marginal products for feed, stocking rate and capital were consistently higher than input costs during the study period. Profit-maximizing levels of input use were higher than the levels of inputs used in West-Central Alabama during the study period. Results indicated that more intensive use of production inputs would increase yield and profits. However, careful interpretation of these results requires consideration of non-profit factors such ns cash Row and risk as well as the specific nature of the data used to develop the production relationship. The method utilized in this study can generally be applied to any aquaculture production system, but the recommendation for more intensive input use is specific to the pond data collected for this study.     

大型藻类在综合海水养殖系统中的生物修复作用

减少水产养殖自身对环境的负面影响是维持水产业持续健康发展的关键所在。大型藻类生物滤器可以有效地吸收、利用养殖环境中多余的营养物质，从而减轻养殖废水对环境的影响，并提高养殖系统的经济输出，被广泛应用于鱼、虾和贝类等的综合养殖系统中，是控制水体富营养化、增进食品安全和对污染水体进行生物修复的有效措施之一。本研究概述了大型藻类生物滤器用于养殖废水生物修复和环境控制的原理、依据、研究现状、修复效果以及应用大型藻类生物滤器产生的效益和存在的问题。     

Economics of Sustainable Intensification of Aquaculture: Evidence from Shrimp Farms in Vietnam and Thailand

There is growing interest in sustainable intensification of aquaculture production. Yet little economic analysis has been done on farm‐level effects of the economic sustainability of production intensification. Data from 83 shrimp farms (43 in Vietnam and 40 in Thailand) were used to identify (through principal component and cluster analyses) 13 clusters of management practices that reflected various scales of production intensity that ranged from 0–1999 kg/ha/crop to 10,000 kg/ha/crop and above, for both Penaeus monodon and Litopenaeus vannamei in Vietnam and Thailand. The clusters identified reflected sets of management practices that resulted in differing yields despite similarities in stocking densities among some clusters. The enterprise budget analysis developed showed that the more intensively managed clusters outperformed the less intensively managed clusters in economic terms. More intensively managed farm clusters had lower costs per metric ton of shrimp produced and were more profitable. The greater yields of shrimp produced per hectare of land and water resources in more intensively managed shrimp farms spread annual fixed costs across a greater volume of shrimp produced and reduced the cost per metric ton of shrimp. Costs per metric ton of shrimp produced decreased from the lowest to the highest intensity level (from US$10,245 at lowest intensity to US$3484 at highest for P. monodon and from US$24,301 to US$5387 for L. vannamei in Vietnam and from US$8184 at the lowest intensity level to US$3817 at the highest intensity level per metric ton for L. vannamei in Thailand). Costs of pond amendments used in shrimp production were particularly high in Vietnam and largely unwarranted, whereas fixed costs associated with the value of land, production facilities, equipment, and labor were sufficiently high in Thailand so that net returns were negative in the long run. Nevertheless, economic losses in Thailand were less at greater levels of intensification. The study demonstrated a clear value proposition for shrimp farmers to use natural resources (such as land) and other inputs in an efficient manner and supports findings from corresponding research on farm‐level natural resource use efficiency. Additional research that incorporates economic analysis into on‐farm studies of sustainable intensification of aquaculture is needed to provide ongoing guidance related to sustainable management practices for aquaculture.     

Economic and Risk Analysis of Tilapia Production in Kenya

Commercial production of tilapia in Kenya has potential for expansion, but growth and development of the tilapia industry in Kenya will depend upon its profitability and the effect of associated risks. Data from pond experiments, on-farm trials, and farm surveys were used to develop enterprise budgets and a risk analysis for nine production scenarios. The nine scenarios include: 1) monoculture of sex-reversed male tilapia fed either rice bran, a pelleted experimental diet, or a pelleted pig finisher diet; 2) clarias monoculture fed with each of the three diets; and 3) tilapia-clarias (sex-reversed male fingerlings) polyculture fed with each of the three diets. Net returns/ha were highest for production with the pig finisher diet, with clarias in monoculture the highest followed by tilapia in monoculture and then the polyculture system. The lowest net returns/ha were obtained with clarias fed rice bran. Profitability was affected by feed cost and tilapia survival. Tilapia monoculture systems had lower probabilities of financial losses than either clarias monoculture or the polyculture system. Use of the pelleted diets also resulted in lower probabilities of financial losses. Lower yields from the rice bran feed scenario resulted in its greater sensitivity to fluctuating costs of rice bran and survival of tilapia.     

海南省渔业生产函数实证分析

海南省是一个海洋大省,自海南建省以来,渔业经济稳步增长,成绩显著。其中,总产量的平均增长率16．70％。2003年,全省渔业总产量为1230690t,捕捞业总产量918280t,养殖产量312410t,分别比1988年增长了110711t,810840t,29627lt。用1990年的可比价计算,渔业总产值的平均增长速度为22．60％,2003年渔业总产值为619909．4万元,占农业总产值的27％,仅次于种植业（占农业总产值的36％）;渔业捕捞业产值为249141万元,养殖业的产值为182703．4万元。     

辽东半岛裙带菜室内常温全人工育苗：双高光控制、温度变化和配子体发育

2010年,作者在辽东半岛成功进行了裙带菜室内常温全人工育苗大规模生产试验,并全程进行了光照强度、温度和配子体发育相关性的研究。研究表明,采用双高光期(≥50μmolphotons/m2·s)调控配子体的生长和发育可达到理想效果。从采苗至度夏前,采用高光照使配子体充分完成营养生长;从度夏结束至幼苗出库前,同样采用高光照,使配子体快速发育形成孢子体并迅速生长。现场观察表明,只要光照强度逾越了诱导发育的阈值,裙带菜配子体在24℃仍然能够正常发育并形成孢子体;幼孢子体能够耐受24～26℃的高温,但是最适生长温度为20～22℃;孢子体越小,耐受高温能力越强。在24～26℃的高温条件下,幼孢子体生长缓慢,较大个体会出现尖端溃烂缺失的现象。在整个育苗过程中,根据温度变化和配子体的显微观察结果因地制宜地对光线进行实时调整。出库前培育的苗帘在幼苗密度、大小和健康方面均达到商业化栽培的要求。     

Economics of fish farming in Saudi Arabia: Analysis of costs of tilapia production

Abstract

Because Saudi Arabia is a substantial importer of fish and its capture fishery is operating beyond maximum sustainable limits, it has a special interest in developing fish farming. It has been encouraging tilapia production. This study examines the costs of tilapia farming in the Central Region of Saudi Arabia using cross sectional data from 23 intensive fish farms. It provides information about the relative importance of different cost items such as variable costs and feed costs in total costs. Also, cost functions are estimated by ordinary least squares and a cubic cost function is found to provide the best fit to the available data. Minimum average cost of production occurs for 201 tonnes of tilapia per year per farm and profit is maximised for a production of 300 tonnes annually per farm. All farms operate at less than profit‐maximising scale and most operate at less than minimum efficient scale. The reasons could be low quality fry, low levels of management expertise in culturing tilapia and the secondary nature of tilapia farming. Lack of water is likely to limit future expansion of tilapia farming in Saudi Arabia.     

河北省扇贝养殖区河口区域石油类污染分析

在河北省扇贝养殖区7条主要人海河流河口区域设立监测站位,于2007年5月枯水期和8月丰水期对水样和沉积物样品中石油类含量进行监测.河口水样平均石油类含量丰水期为0.94 mg/L,超标18.8倍;枯水期为0.51 mg/L,超标10.2倍;丰水期明显高于枯水期.河口沉积物中石油类含量丰水期为473μg/g,为标准值的0.95倍;枯水期为777μg/g,为标准值的1.55倍;部分河口沉积物中石油类含量超标严重.河口区域水体石油类污染的主要原因是大陆径流.     

Estimating oxygen consumption of rainbow trout (Oncorhynchus mykiss) in a raceway: A Precision Fish Farming approach

The Precision Fish Farming (PFF) approach was applied to the estimation of fish oxygen consumption of rainbow trout in a raceway farm. A dynamic model, simulating the evolution of Dissolved Oxygen concentration, was identified: the daily oscillation of fish oxygen consumption rate was simulated by means of a sinusoidal function. The model was applied to the data set collected during a four-week field study, which was carried out in July 2019. Water temperature and Dissolved Oxygen concentration were measured with an hourly frequency in farm influent and effluent. Fish biomass was monitored on a daily basis by combining the data provided by a state-of-the art system for non-invasive estimation of fish weight distribution with mortality counting. The monitoring period was partitioned into two time-windows, as fish was not fed during the first two weeks. These windows were further partitioned into a calibration and validation set. Three model parameters, i.e. the average daily respiration rate, the amplitude of its daily oscillation, and its phase were estimated by fitting the model output to the time series of DO concentration in the effluent. The results of the calibration show that: 1) the daily average oxygen consumption rate is consistent with the literature; 2) the amplitude of the daily oscillation when fish is regularly fed is more than twice that estimated for fasting fish. The results of the validation suggest that the model could be used to implement a cost-effective automatic control of oxygen supply, based on the short-term prediction of oxygen demand.     

枸杞岛海藻场角蝾螺夏季摄食选择性及其生态学意义

于2013年夏季对枸杞岛海藻场螺类优势种角蝾螺进行了稳定同位素、摄食选择性、消化代谢物粒径等系列实验.稳定同位素结果显示,角蝾螺是牧食性生物,在藻场中的营养级为2.12,属初级消费者,底栖海藻是角蝾螺的主要食源,贡献率为94.5％;摄食选择性实验结果显示,角蝾螺具有较宽的摄食选择,能够摄食海带、铜藻、粗枝软骨藻等1 1种大型藻类,其中铜藻及蜈蚣藻是枸杞岛潮下带的重要优势种;消化代谢物实验结果显示,角蝾螺的啃食作用能为藻场碎屑提供增量,角蝾螺对海藻场碎屑的增量为(0.016 ～0.094)g/d,经过啃食及消化作用产生的碎屑主要粒级为1Φ(＞ 250 μm).稳定同位素分析—摄食选择偏好实验—螺类消化代谢物粒径分析的系列研究表明,角蝾螺在枸杞岛海藻场的群落食物网中,可以起到连接牧食食物链和碎屑食物链的重要作用.     

Technical Efficiency of Tank Culture Systems in Peninsular Malaysia: An Application of Data Envelopment Analysis

The demand for animal protein especially fish is growing rapidly perhaps due to rapid expansion of population, increased incomes, and changes in eating habits and life styles of consumers. Capture fisheries are currently overexploited and their yield has become stagnant over the last decades and, in some cases, has even declined. Nevertheless, aquaculture has the potential to meet these challenges if well practiced. The study therefore, aims to estimate Technical Efficiency of tank culture systems using Data Envelopment Analysis (DEA). Additionally, it also investigates the determinants of technical inefficiency by employing a regression model. The estimated technical efficiency was 0.89, which means that the fish farmers can reach full technical efficiency through reducing their input usage by another 11%. Results indicate that farmer’s experience, educational level, extension training, job status, and water management have positive and statistically significant impacts on technical efficiency. Therefore, increase in any of these factors will have a direct impact on technical efficiency.     

The potential of aquaculture sole production in Europe: Production costs and markets

Sole is a high-value flatfish species that is highly favored in many European markets. Nowadays most sole comes from capture fisheries; however, wild supply has been decreasing because of decreasing catches due to stocks overexploitation. Due to its high price and declining landings, as well as a desire by farmers to diversify their operations, there has been an expansion in sole aquaculture production in recent years and there are ambitious plans for further growth. In this paper we assess the potential for sole aquaculture in Europe using raceways. This is done by analyzing the production costs of sole farms and the price evolution in European sole markets.     

东太平洋不同海区茎柔鱼肌肉脂肪酸组成分析与比较

茎柔鱼(Dosidicus gigas)是一种广泛分布在东太平洋的大洋性头足类,具有重要的经济价值。本研究以捕获自3个作业海区的茎柔鱼为研究对象,对其肌肉脂肪酸含量进行测定、分析和比较。结果显示,各海区茎柔鱼肌肉脂肪酸种类和组成存在显著差异。秘鲁外海样品所含脂肪酸种类最多(共28种),中东太平洋赤道海域样品含有脂肪酸27种,而智利外海样品所含脂肪酸种类最少,只检测出24种。脂肪酸均以多不饱和脂肪酸为主(59.68%~69.28%),其次是饱和脂肪酸(20.71%~27.28%)和单不饱和脂肪酸(10.01%~13.04%)。各海区茎柔鱼肌肉中C16:0、C18:0、C20:1n9、C18:2n6、EPA和DHA含量较高,均占脂肪酸总含量的81%以上。脂肪酸组成的空间异质性主要是由各海区C16:0、C18:2n6、C20:4n6和DHA的含量不同造成的,这种差异可能与各海区海洋环境、食物来源和个体能量需求的差别有关。本研究说明了脂肪酸分析在茎柔鱼食性研究中的潜在作用,对分析不同海区茎柔鱼营养成分和资源合理利用有一定的应用价值。     

丁鱥不同生长阶段肌肉脂肪酸和微量营养元素的比较

对丁鱥不同生长阶段鱼体肌肉中脂肪酸组成及微量营养元索含量进行了比较。结果表明：丁鱥不同生长阶段肌肉中的脂肪酸含量及组成有明显差异。脂肪酸总量、不饱和脂肪酸总量和饱和脂肪酸总量，亲鱼均高于幼鱼和成鱼，成鱼均高于幼鱼；不饱和脂肪酸／饱和脂肪酸总量，成鱼和亲鱼均高于幼鱼；同时，成鱼和亲鱼肌肉中高度不饱和脂肪酸花生三烯酸、花生四烯酸、二十二碳五烯酸和EPA、DHA含量明显高于幼鱼肌肉。成鱼和亲鱼肌肉中微量营养元素Fe和Mn含量显著低于幼鱼（P〈0．05）；亲鱼肌肉中Zn含量显著低于成鱼和幼鱼（P（0．05），成鱼显著高于幼鱼（P（0．05）；亲鱼肌肉中Cu含量显著低于成鱼和幼鱼（P〈0．05）。     

丁(鱼岁)不同生长阶段肌肉脂肪酸和微量营养元素的比较

对丁不同生长阶段鱼体肌肉中脂肪酸组成及微量营养元素含量进行了比较。结果表明:丁不同生长阶段肌肉中的脂肪酸含量及组成有明显差异。脂肪酸总量、不饱和脂肪酸总量和饱和脂肪酸总量,亲鱼均高于幼鱼和成鱼,成鱼均高于幼鱼;不饱和脂肪酸/饱和脂肪酸总量,成鱼和亲鱼均高于幼鱼;同时,成鱼和亲鱼肌肉中高度不饱和脂肪酸花生三烯酸、花生四烯酸、二十二碳五烯酸和EPA、DHA含量明显高于幼鱼肌肉。成鱼和亲鱼肌肉中微量营养元素Fe和Mn含量显著低于幼鱼(P<0.05);亲鱼肌肉中Zn含量显著低于成鱼和幼鱼(P<0.05),成鱼显著高于幼鱼(P<0.05);亲鱼肌肉中Cu含量显著低于成鱼和幼鱼(P<0.05)。     

The use of fermented soybean meal and squid by-product blend as a substitute for fish meal in practical diets for climbing perch,Anabas testudienus (Bloch, 1792), pond culture: Growth performance and economics analysis

A feeding trial was conducted to evaluate the effects of different ratios of fish meal (FM) to a fermented blend (FB: fermented soybean meal and squid by-product blend) on growth and economic performance of climbing perch, Anabas testudineus (Bloch, 1792), in earthen ponds. Five diets were prepared where FB was substituted for 0 (D1), 25 (D2), 50 (D3), 75 (D4), or 100% FM protein (D5), while a commercial diet (D6) was used for comparison. Triplicate groups of fish (1.03 ± 0.07 g) were fed twice daily up to satiation for 70 days in earthen ponds. No significant (P > 0.05) differences were found in growth performance of fish fed D1, D2, D3, and D6 diets, while fish growth decreased significantly (P < 0.05) in D4 and D5 groups. Feed intake decreased (P < 0.05) with the increasing levels of FB with no significant difference in the feed conversion ratio, which ranged from 1.98 to 2.08. The fish survival decreased significantly in D5 alone. While considering the overall production, the total yield and economic return were found to be highest in D2 (64176.7 TK ha^?1) and lowest in D5 (14418.3 Tk. ha^?1). Based on the present experimental condition, it is concluded that FB can economically be included in aquafeed as a substitute for up to 50% of FM protein from the diets of climbing perch.     

Estimating production costs of preadult redclaw crayfish,Cherax quadricarinatus,reared in a commercial nursery system: A stochastic bioeconomic approach

A stochastic bioeconomic model was used to estimate the production cost and risk factors affecting economic performance of juvenile redclaw crayfish, Cherax quadricarinatus, commercial nursery production, in a farm located in Baja California Sur, Mexico. At harvest, the biological submodel showed there is 95% confidence to obtain an average weight of 19.98 g, with 126,341/ha surviving organisms, representing 84% survival. Biomass was 2.5 t/ha, with a feed conversion ratio (FCR) of 0.98, reflecting the efficient adaptation of the species to culture conditions. The economic submodel showed that at Day 90, there is 95% confidence that the cost of producing a preadult will be US$0.090 or US$4.55/kg. With increasing demand and worldwide sale prices of US$9/kg, there is a potential market for 20–30 g redclaw reared in intensive lined ponds. Sensitivity analyses showed that the regression coefficients from a second‐order polynomial used for calculation of FCR associated with time (a₂ and a₁) were the most important parameters influencing the production cost. Mortality rate and parameters used to calculate individual weight also had considerable influence on production cost. The bioeconomic analysis contributes significantly to establishing the economic viability of the intensive three‐phase production system.     

Evaluation of the robustness of optical density as a tool for estimation of biomass in microalgal cultivation: The effects of growth conditions and physiological state

We evaluate the robustness of optical density (OD) as a tool in the assessment of the biomass of the cryptophyte Rhodomonas salina under different growth conditions. We measure the OD under three different wavelengths, 550, 665 and 750 nm. We find, as expected, that growth rates of the microalga depend strongly on growth conditions, being highest in saturating light conditions under non‐limiting nitrogen (N) availability. OD – cell count relationships are strong and well defined regardless of the growth conditions and wavelength used for measurement. However, measuring within the absorption range of chlorophyll, at 550 and 665 nm, does give higher regression coefficients under conditions leading to a high cell chlorophyll content, while the coefficients of determinations are slightly higher when cell chlorophyll content is low. We conclude that to use OD as a proxy for biomass under large‐scale production of microalgae, it is important to take into account that the precise relationship between OD and algal biomass does depend on factors such as irradiance and nutrient availability, and hence the physiological state of the microalgae as well as the production conditions. Errors in estimation of biomass may range from 44% to 95%, if these factors are not taken into consideration.