12月全国水产品价格分析

<正>一、基本情况据对全国80家水产品批发市场成交价格情况监测统计,12月份全国水产品综合平均价格为23.39元/公斤,环比上涨1.66%,同比下跌1.5%。另据可对比的45家水产品批发市场的成交情况监测统计,2018年12月份全国水产品市场成交量额     

我国大黄鱼养殖产业现状及对策研究(下)

正四、大黄鱼养殖成本收益情况——以宁德地区网箱养殖模式为例大黄鱼养殖成本构成可分为变动成本与固定成本。饲料支出、苗种支出、鱼药支出等构成可变成本;固定成本包括固定员工工资、固定资产折旧、设备支出、设备维修费、利息支出等。经统计计算可得宁德地区网箱养殖大黄鱼相关成本,如表7、表8和表9所示。     

海水工厂化养鱼多点在线水质监测系统的研究

对海水工厂化养鱼水质监测系统进行了研究，开发出一种多点在线水质监测系统，该系统集多路数据采集、测量、转换、计算、储存、显示、打印、报警等功能于一体，可同时在线监测6个不同监测点的水质情况；对每一个监测点，可同时监测其溶解氧、温度、电导率、pH、氧化还原电位、盐度等6个参数。     

5月全国水产品价格分析

正据对全国80家水产品批发市场成交价格情况监测统计,5月份全国水产品综合平均价格为23.34元/kg,环比上涨1.89%,同比下降1.22%。另据可对比的38家水产品批发市场的成交情况监测统计,2020年5月份全国水产品市场成交量52.09万吨,同比下降9.48%;成交额127.26亿元,同比下降2.50%。一、海水产品价格情况     

多波束深水网箱声学监测仪的研究

研究了一种声学监测设备,使网箱养殖者能在海水能见度较低时实现对鱼群的实时监测,进而掌握深水网箱中鱼群的生存状况。该声学监测仪由7个独立通道构成,能同时输出探测图像并通过监测仪的评估软件对数据进行分析。试验结果表明该设备能够对深水网箱中的生物量进行估计,可用于鱼类生长情况研究并监测鱼群的逃逸情况。     

11月全国水产品市场价格监测简报

<正>一、基本情况据对全国80家水产品批发市场成交价格情况监测统计,11月份全国水产品综合平均价格为22.02元/公斤,与去年同期基本持平,环比下跌1.25%。另据可对比的40家水产品批发市场的成交情况监测统计,2018年11月全国水产品市场成交量额双增。其中,成交量为89.78万吨,同比增长3.41%;成交额为177亿元,同比增加3.2%。     

8月全国水产品价格分析

正一、基本情况据对全国80家水产品批发市场成交价格情况监测统计,8月份全国水产品综合平均价格为23.33元/公斤,环比下跌2.22%,同比上涨1.90%。另据可对比的57家水产品批发市场的成交情况监测统计,2018年8月份全国水产品市场成交量额双增。其中,成交量为78.87万吨,同比上涨0.32%;成交额为196.57亿元,同比上涨2.18%。     

江苏河蟹养殖成本效益调查分析

该文基于江苏省河蟹产业技术体系的示范基地监测和主产区示范户调研数据,分析了2018年的河蟹养殖成本收益情况及变化。结果显示,近年来江苏河蟹养殖结构稳定,不同经营主体养殖效益明显不同,河蟹养殖成本有逐年递增趋势。其中人工、渔药和土地支出成本上升最为迅速,苗种费、水电、饵料费用相对稳定,规模经营主体较个体养殖盈利和抗风险能力强。在调研分析的基础上,对主产区河蟹养殖风险因素进行了对比分析,提出降本提效的建议。     

4月水产品市场价格监测简报

正据对全国80家水产品批发市场成交价格情况监测统计,4月份全国水产品综合平均价格为25.45元/kg,环比上涨0.92%,同比上涨11.10%。另据可对比的46家水产品批发市场的成交情况监测统计,2021年4月全国水产品批发市场成交量64.58万吨,同比上涨2.58%;成交额191.92亿元,同比上涨18.95%。一、海水产品价格情况4月份,海水产品价格46.26元/kg,环比下降0.24%,同比上涨8.24%。     

11月水产品市场价格监测简报

正据对全国80家水产品批发市场成交价格情况监测统计,11月份全国水产品综合平均价格为23.10元/kg,环比下降0.78%,同比上涨4%。另据可对比的39家水产品批发市场成交情况监测统计,2020年11月全国水产品批发市场成交量93.76万t,同比上涨1.29%;成交额188.25亿元,同比下降1.80%。一、海水产品价格情况11月份,海水产品价格42.51元/k g,环比下降0.4 9%,同比上涨5.92%。海水鱼类环比同比均上涨。据监测,海水鱼类价格环比上涨1.02%,     

Community‐based monitoring of small‐scale fisheries with digital devices in Brazilian Amazon

Fisheries management is potentially a short‐term measure for reducing floodplain fisheries degradation. This objective can only be achieved if adequate measures to improve fishery governance and ecosystem conservation are taken. The monitoring of fisheries management is likely to be important for understanding the effectiveness of local rules and the impacts on aquatic biodiversity. Given that monitoring is the periodic assessment of fish stock characteristics regarding reference data, adopting tools and procedures for monitoring at different scales is a challenging task. Information and Communication Technologies (ICT) have enabled local communities to gather data on key resources in a cost‐effective way. This article presents a community‐based monitoring of fisheries based of smartphones that supports the annual fishing quotas and legal harvest permits procedures. The precision of community‐based monitoring data is assessed and a model to integrate these data into a large‐scale monitoring scheme examined. Data collection performance was evaluated at communities in the Kaxinawá Nova Olinda Indigenous Territory, in the State of Acre, where fishery management was monitored. The results indicate that voluntary collectors are able to provide data with precision comparable with government agency measurements, but at lower cost.     

Optimal design of pumping stations of inland intensive fishfarms

An algorithm for selection of least cost or optimum pump combinations in water supply systems and to evaluate the system's energy cost of inland intensive fishfarms is presented. The model is based on solving a non-linear programming problem. Optimum design refers to the selection of pump type, capacity, and number of units that results in minimum design and operating costs for a given water demand curve. The optimization process consists of three main steps: (1) determination of fishfarm daily water requirements; (2) determination of all sets of pumping stations that satisfy the maximum requirements of flow and energy head of the fishfarm water distribution network; and (3) selection of the least-cost set among the feasible sets of pumping stations. The model was established based on data from an actual eel fishfarm in southern Spain. Application of the model shows that the optimal solution with the pump operation scheme at a constant rate (maximum requirements of flow) saved 70% of the actual total annual cost of the pumping station. The optimal solution with a variable pumping rate (pumped flow adjustment to match demand) saved 92% of the actual total annual cost with all fixed speed pump groups. Savings about 95% were obtained when one variable speed pump group was included in the optimal solution.     

Size Economies of a Pacific Threadfin Polydactylus sexfilis Hatchery in Hawaii

A spreadsheet model has been developed to determine the viable scale for a commercial Pacific threadfin Polydactylus sexfilis hatchery in Hawaii. The production scheme is modeled after current practices performed at the Oceanic Institute in Waimanalo, Hawaii. For a hatchery enterprise producing 1.2 million fry per year, the cost associated with raising one 40‐d‐old 1.00‐g fry is estimated at 22.01ø. The largest variable costs are in labor and supplies, which comprise 49% and 9% of the total production cost. The combined annualized fixed cost for development and equipment is approximately 12% of total production cost. At a sale price of 25ø per fry, the 20‐yr internal rate of return (IRR) is 30.63%. In comparison to the 22.01ø unit cost for 1.2 million fry production, analyses of smaller enterprises producing 900,000 and 600,000 fry per year reflected significant size diseconomies with unit costs of 27.41ø and 38.82ø, respectively. Demand to support a large scale Pacific threadfin commercial hatchery is uncertain. Since smaller scale commercial hatcheries may not be economically feasible, facilities may seek to outsource live feed production modules or pursue multiproduct and multiphase approaches to production. An analysis of the production period length, for example, indicates that the cost for producing a day‐25 0.05‐g fry is 17.25ø before tax and suggests the financial implications of transferring the responsibility of the nursery stage to grow‐out farmers. Evaluation of the benefits gained from changes in nursery length, however, must also consider changes in facility requirements, mortality, and shipping costs associated with transit, and the growout performance of and market demand for different size fry. Sensitivity analyses also indicate the potential cost savings associated with the elimination of rotifer, microalgae, and enriched artemia production. Managerial decisions, however, must also consider the quality and associated production efficiencies of substitutes.     

Assessment of the new generation aeration systems efficiency and water current flow rate,its relation to the cost economics at varying salinities for Penaeus vannamei culture

The selection of aerators and correct numbers can play an essential role in reducing the cost of production in aquaculture. The new generation aerators, namely spiral leaf, air‐jet, submersible and impeller, used in aquaculture, were assessed for its aeration efficiency and energy cost compared with the commonly used paddle wheel aerator. Of the aerators tested, the impeller had the highest aeration efficiency of 2.098 kg O₂/kW hr, followed by paddle wheel with 1.436 kg O₂/kW hr at 20‰ salinity. The spiral and air‐jet aerators had maximum aeration efficiency of 1.326 and 1.419 kg O₂/kW hr, respectively, at 35‰ salinity. The submersible aerator was not efficient as its maximum efficiency was 0.380 kg O₂/kW hr. The water flow by paddle wheel was 3 ft/sec and also provides better coverage than other types of aerators. The efficiency of aerators was high in optimum salinities (20‰ and 35‰) than the low or high saline condition. The average energy cost of shrimp pond aeration per hectare was lowest for impeller, followed by paddle wheel aerator. The study provided economic comparisons of vannamei culture using different aeration systems by keeping a uniform set of economic assumptions. Shrimp farms with impellors can give 14%–25% high returns across salinities, whereas spiral leaf can provide 5% high returns at 35‰ salinity. The combination of the type of aerators and the calculated use based on the salinity of the culture systems can result in energy‐saving and also a reduction in the production cost.     

An analysis of the energetic cost of the branchial and cardiac pumps during sustained swimming in trout

Experimental data are available for the oxygen cost of the branchial and cardiac pumps in fish. These data were used to theoretically analyze the relative oxygen cost of these pumps during rest and swimming in rainbow troutSalmo gairdneri. Efficiency of the heart increases with activity and so the relative oxygen cost of the cardiac pumps decreased from 4.6% at rest to 1.9% at the critical swimming speed. The relative oxygen cost of the branchial pump is significant in the resting and slowly swimming fish, being 10 to 15% of total oxygen uptake. However, when swimming trout switch to a ram mode of ventilation, a considerable saving in oxygen cost is accrued by switching the cost of ventilation from the branchial to the tail musculature. Thus, the relative oxygen cost of the branchial and cardiac pumps actually decreases at critical swimming speed compared to rest and therefore is unlikely to be a major limiting factor in maximum oxygen delivery to the tissues.     

基因型与环境互作条件下凡纳滨对虾多性状复合育种方案的遗传和经济评估

依据凡纳滨对虾多性状复合育种方案,模拟选择20个世代,预测和评估了目标性状（收获体质量（BW）,存活率（SR）和饲料摄入量（FI））的遗传进展及经济效益。利用选择指数理论,估计目标性状的选择反应、遗传进展以及育种目标;并对影响利润（RP）和效益成本比率（BCR）的生物学参数（遗传力、育种目标是否包括FI）,经济学参数（对虾价格、饲料价格、贴现率、初投资、年费用）和运行参数（首次回报年份、扩繁效率）进行了敏感性分析。结果表明,在基础参数值下,BW、SR和FI每个世代的选择反应分别为0.86g,4.70%和1.54g;育种方案执行20年产生的RP和BCR分别为862747.91万元和844.26;敏感性分析显示,在所有参数中,扩繁效率对RP和BCR的影响最大。基因型与环境互作的敏感性分析表明：重排效应（养殖环境对同一基因型个体在不同环境中育种值排序的影响）对RP和BCR的影响较大。规模效应（养殖环境对遗传方差的影响）对RP和BCR的影响不如重排效应明显。因此,从遗传学和经济学角度考虑,如果育种目标性状在不同的区域间存在较强的基因型与环境互作效应,应针对不同的环境设置多个独立的育种核心群体,以期获得更高的RP和BCR。     

A preliminary appraisal of the contribution of recreational fishing to the fisheries sector in north-west Trinidad

Abstract An assessment of the recreational fishery in north-west Trinidad was made by questioning participants about the principal fishing methods used, location of activities, catches, effort and cost of fishing. Surface handline methods (live baiting [à la vive] and trolling) and rod and line (banking) were the most common methods used and were pursued mainly in the summer months (April to August). Total fish landings from the fishery were estimated at 1000 t year^-1, equivalent to about 10% of commercial catches for Trinidad. The principal species caught were kingfish, Scomberomorus cavalla (Cuv.), carite, Scomberomorus brasiliensis (Cuv.), cavalli, Caranx hippos (L.), snappers, Lutjanus spp., and groupers, Epinephelus spp. Many of the fishermen sold their catch to offset the costs of the fishing trip and thus competed with commercial fishermen. Recommendations for monitoring and possibly regulating the fishery through a licensing scheme are made.     

Oxygen consumption and swim speed of the harbor porpoise Phocoena phocoena

ABSTRACT: The rate of oxygen consumption and energetic cost of locomotion of captive harbor porpoises Phocoena phocoena were studied in Hokkaido, Japan, using respirometry together with externally attached devices (a data logger) that recorded swim speed and dive depth. Harbor porpoises swam freely in a tank at a swim speed ranging 0.5–4.2 m/s. Swimming during most dives was relatively slow with mean swim speed being 0.76–0.91 m/s. Oxygen consumption rate of the swimming harbor porpoise increased with swim speed according to a cubed function. The minimum cost of transport during underwater swimming in the harbor porpoise was 2.39–2.43 J/kg per m at an average swim speed of 1.3–1.5 m/s. However, porpoises usually swam slower to conserve energy and dived aerobically. This explains why harbor porpoises can dive repeatedly and continuously without extended rest at the sea surface.     

On the drivers of cost changes in the Norwegian salmon aquaculture sector: a decomposition of a flexible cost function from 2001 to 2014

Abstract

Since 2005, Norwegian salmon farmers have experienced increasing unit costs, contrasting pre-2005 trends characterized by innovations, rapid productivity growth, and diminishing unit costs. This article investigates these cost changes using a panel of salmon producers. The drivers behind cost changes in the industry are identified for the period of 2001–2014 using a flexible cost function. In particular, it is explored how cost changes can be attributable to scale economies, negative productivity shocks, production expansion, and input prices. The results indicate that cost increases in the sector are affected by external factors out of the control of individual firms such as input prices and environmental conditions like sea lice.     

Prolonged Culture Period on Production Cost and Factor Input: A Case from the Pacific Oyster,Crassostrea gigas,Farming Industry in Yunlin County,Taiwan

The Yunlin coastal area is the largest oyster culture in Taiwan; however, the oyster farmers reported the negative impact of a prolonged oyster culture period and an increased operating cost in 2010. This study uses the translog cost function to consider the possibility of an oyster culture period extension to estimate oyster cost elasticity, own‐price elasticities, and cross‐price (substitution) elasticities, to evaluate whether the oyster farming industry in Yunlin County has economies of scale, and to assess the relationship with a substitution of inputs. We found that the Yunlin oyster culture has economies of scale, and that the oyster farmers can expand production scale to reduce costs. The own‐price elasticities of demand for inputs are less than 1, indicating fairly inelastic factor demands in oyster production. The oyster farming industry displays strong substitutability between the prolonged culture period and capital input, suggesting that the oyster farming industry is more responsive to a higher prolonged culture period cost, in terms of capital input.