Comparative economic performance and carbon footprint of two farming models for producing Atlantic salmon (Salmo salar): Land-based closed containment system in freshwater and open net pen in seawater

Ocean net pen production of Atlantic salmon is approaching 2 million metric tons (MT) annually and has proven to be cost- and energy-efficient. Recently, with technology improvements, freshwater aquaculture of Atlantic salmon from eggs to harvestable size of 4–5 kg in land-based closed containment (LBCC) water recirculating aquaculture systems (RAS) has been demonstrated as a viable production technology. Land-based, closed containment water recirculating aquaculture systems technology offers the ability to fully control the rearing environment and provides flexibility in locating a production facility close to the market and on sites where cost of land and power are competitive. This flexibility offers distinct advantages over Atlantic salmon produced in open net pen systems, which is dependent on access to suitable coastal waters and a relatively long transport distance to supply the US market. Consequently, in this paper we present an analysis of the investment needed, the production cost, the profitability and the carbon footprint of producing 3300 MT of head-on gutted (HOG) Atlantic salmon from eggs to US market (wholesale) using two different production systems—LBCC-RAS technology and open net pen (ONP) technology using enterprise budget analysis and carbon footprint with the LCA method. In our analysis we compare the traditional open net pen production system in Norway and a model freshwater LBCC-RAS facility in the US. The model ONP is small compared to the most ONP systems in Norway, but the LBCC-RAS is large compared to any existing LBCC-RAS for Atlantic salmon. The results need to be interpreted with this in mind. Results of the financial analysis indicate that the total production costs for two systems are relatively similar, with LBCC-RAS only 10% higher than the ONP system on a head-on gutted basis (5.60 US$/kg versus 5.08 US$/kg, respectively). Without interest and depreciation, the two production systems have an almost equal operating cost (4.30 US$/kg for ONP versus 4.37 US$/kg for LBCC-RAS). Capital costs of the two systems are not similar for the same 3300 MT of head-on gutted salmon. The capital cost of the LBCC-RAS model system is approximately 54,000,000 US$ and the capital cost of the ONP system is approximately 30,000,000 US$, a difference of 80%. However, the LBCC-RAS model system selling salmon at a 30% price premium is comparatively as profitable as the ONP model system (profit margin of 18% versus 24%, respectively), even though its 15-year net present value is negative and its return on investment is lower than ONP system (9% versus 18%, respectively). The results of the carbon footprint analysis confirmed that production of feed is the dominating climate aspect for both production methods, but also showed that energy source and transport methods are important. It was shown that fresh salmon produced in LBCC-RAS systems close to a US market that use an average US electricity mix have a much lower carbon footprint than fresh salmon produced in Norway in ONP systems shipped to the same market by airfreight, 7.41 versus 15.22 kg CO₂eq/kg salmon HOG, respectively. When comparing the carbon footprint of production-only, the LBCC-RAS-produced salmon has a carbon footprint that is double that of the ONP-produced salmon, 7.01 versus 3.39 kg CO₂eq/kg salmon live-weight, respectively.     

Ecological impacts of small hydropower plants on headwater stream fish: from individual to community effects

Hydroelectricity is increasingly used worldwide as a source of renewable energy, and many mountain ranges have dozens or hundreds of hydropower plants, with many more being under construction or planned. Although the ecological impacts of large dams are relatively well known, the effects of small hydropower plants and their weirs have been much less investigated. We studied the effects of water diversion of small hydropower plants on fish assemblages in the upper Ter river basin (Catalonia, NE Spain), which has headwater reaches with good water quality and no large dams but many of such plants. We studied fish populations and habitat features on control and impacted reaches for water diversion of 16 hydropower plants. In the impacted reaches, there was a significantly lower presence of refuges for fish, poorer habitat quality, more pools and less riffles and macrophytes, and shallower water levels. We also observed higher fish abundance, larger mean fish size and better fish condition in the control than in impacted reaches, although the results were species‐specific. Accordingly, species composition was also affected, with lower relative abundance of brown trout (Salmo trutta) and Pyrenean minnow (Phoxinus bigerri) in the impacted reaches and higher presence of stone loach (Barbatula quignardi) and Mediterranean barbel (Barbus meridionalis). Our study highlights the effects of water diversion of small hydropower plants from the individual to the population and community levels but probably underestimates them, urging for further assessment and mitigation of these ecological impacts.     

Main stem movement of Atlantic salmon parr in response to high river temperature

Atlantic salmon become thermally stressed when water temperatures exceed 23 °C. To alleviate this stress, they behaviourally thermoregulate by moving to patches of cold water, often forming large aggregations. These patches are known as thermal refuges. Given the consensus that climate change will increase temperatures in Atlantic salmon catchments, thermal refuges will become increasingly important in minimising summer mortalities. While the behaviour of salmonids within thermal refuges is fairly well understood, less is known about their main stem movement in search of thermal refuges or its thermal and temporal cues. We detail the results of a PIT telemetry study to investigate the main stem movement behaviour of thermally stressed Atlantic salmon parr in a temperature‐impacted river. PIT antennas placed around two thermal refuges and at the upstream and downstream limits of their surrounding reach were used to record the movement of salmonids during a heatwave. We observed parr movement at the upstream and downstream antennas 135 min prior to the occurrence of the midpoint of aggregations in the thermal refuges, indicating that Atlantic salmon parr make reach‐scale movements in search of cool water prior to aggregating. Logistic regression showed that the number of degree hours >28 °C predicted the occurrence of main stem movement with a good degree of accuracy, indicating that this temperature represents a fundamental threshold causing Atlantic salmon parr to move towards cool water. Such data could be instrumental in allowing river managers to place limits on human activity within rivers, allowing salmon populations time to recover following heat stress events.     

Recruitment of sympatric vendace (Coregonus albula) and whitefish (C. lavaretus) is affected by different environmental factors

Vendace and whitefish in Lake Osensjøen (boreal south‐east Norway) were studied by means of gillnet test fishing (1976–2013) and hydro acoustic acquisition (1986–2011). Vendace increased in number between 1998 and 2009 while growth and size at maturity decreased. The relative density of whitefish decreased in the pelagic habitat, whereas growth and size remained the same. Both species exhibited varying year‐class strength. Whereas strong year‐classes of both species became less frequent after 1980 than before this, this seemed to change after 2000, especially for vendace. Generalised additive models suggested a strong positive relationship between July/August mean air temperature and year‐class strength of both vendace and whitefish. Whitefish recruitment was also negatively affected by the new regulation regime implemented since 1981, and positively correlated with water level after hatching and by late ice off. The reason for the diverging impacts of environmental factors on the two species may be that vendace spawn in deeper waters that whitefish do. The results indicate that increasing summer temperatures benefit recruitment of both species, whereas low water level and early ice off will harm whitefish recruitment. Both trends are caused by climate warming. It may be speculated that increased density of the specialised plankton feeding vendace may affect the algal community through increased predation on herbivorous zooplankton and potentially affect the trophic state of the lake.     

澧水常德段水环境质量现状分析与评价

比照《地表水环境质量标准》（GB3838—2002），运用综合评价指数法，对2007年度澧水常德段石门县三江口、津市市窑坡渡、安乡县沙河口3个监测断面的水质现状进行分析与评价。结果表明：澧水常德段水质总体上达到地表水Ⅲ类标准，水质良好，其中石门县三江口和安乡县沙河口所有监测项目均处于标准值范围，津市市窑坡渡存在粪大肠菌群超标现象。今后应加强水环境监测能力建设，重视水资源合理开发利用，统筹安排生产、生活用水，严格控制排污量，为地方经济社会发展提供可持续的水利保障。     

卡尔费休法测定胡椒水分含量的比较研究

以蒸馏法测定胡椒水分含量结果为基准，比较卡尔费休容量法测定胡椒(Piper nigrum L.)水分的准确度和精确度，并获得校正系数平均值2.18。结果表明：卡尔费休法可达到蒸馏法的测定准确度和精确度，而且操作简便，是可靠的胡椒水分含量测定方法。     

日本农业保险运行机制与服务作用的思考和借鉴

2004年以来,中国农业保险发展迅速,目前已覆盖全国各地。但仍然存在农业保险制度尚不完善、缺乏稳定持续的政策支持、当事人的权利义务关系缺乏规范、农村基层机构参与农业保险存在法律障碍及政府部门职责分工不明等问题。以日本为例,介绍日本农业保险制度,指出其存在强制性与任意性加入相结合、政府负担部分保险费及共济、保险、再保险重层保险体系等特征,从共济加入方式、损失评估规定和共济金支付方式3个方面分析了农业保险运行机制,发现其具有减轻农民损失、稳定农业经营,提高凝聚力、促进协同发展,提高防灾、抗灾能力等社会化服务功能,为中国目前面临的农业保险业建设提出了相应的建议。     

台湾农产品“希望广场”的考察与启示

为提高我国农产品流通的效率,寻求防止农产品价格大起大落现象的办法,作者于今年五月赴台北农产品＂希望广场＂进行了考察。本文介绍了＂希望广场＂的组建历史、运营模式及绩效、得到的支持及其作用机制等,归纳了对大陆农民组织和农产品流通体系的政策启示。作者认为,农产品直销市场在农产品流通中发挥着显著的作用,对提高消费者福利和增加农民收入有很大帮助,加强农产品直销市场建设刻不容缓。应该将农业市场化建立在农民组织的载体之上,充分发挥农民合作组织在农产品流通中的作用。     

应用VITEK2全自动微生物鉴定系统检测养殖用水中的大肠杆菌

采用国家相关的检验养殖用水标准方法、API 20E微生物生化试验、VITEK2全自动微生物鉴定系统，对养殖用水样品进行了大肠杆菌的检测方法比较和鉴定。VITEK2鉴定系统自动打印的实验报告和API 20E微生物生化试验的判读比对结果显示：3个参试样品分别为阴沟肠杆菌、产气肠杆菌和大肠埃希菌，VITEK2与API 20E两种方法的鉴定结果符合率100%。从实验可知，利用VITEK2全自动微生物鉴定系统，对被污染的养殖用水中细菌源的鉴定速度快，方法简便，结果准确、实用。此方法也可用于各种污染环境及食品污染源的