Production economics of shellfish aquaculture in Atlantic Canada: a preliminary analysis

Abstract. The determinants of shellfish aquaculture production in Atlantic Canada are investigated through the estimation of Cobb-Douglas production functions, relating production output to several independent input variables. The statistical analysis is carried out for both mussel and oyster culture, based on data collected in a survey of aquaculturists. For both production processes, capital investment and labour usage have a significant effect on production output. In addition, the level of managerial experience (estimated by the number of years in operation) plays a significant role in determining oyster production levels. Increasing returns to scale seem to exist for oyster culture techniques, while mussel culture exhibits constant returns to scale. Furthermore, our preliminary analysis suggests that from a private operator's perspective, labour usage on the average mussel farm is roughly optimal, while for the average oyster farm, an increased use of labour could be profitable. In contrast, for both mussel and oyster culture processes, there appears to be no economic incentive for increased capital investment.     

Natural and anthropogenic drivers of foraging behaviour in bottlenose dolphins: Influence of shellfish aquaculture

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Probiotics in fish and shellfish culture: immunomodulatory and ecophysiological responses

Aquaculture is emerging as one of the most viable and promising enterprises for keeping pace with the surging need for animal protein, providing nutritional and food security to humans, particularly those residing in regions where livestock is relatively scarce. With every step toward intensification of aquaculture practices, there is an increase in the stress level in the animal as well as the environment. Hence, disease outbreak is being increasingly recognized as one of the most important constraints to aquaculture production in many countries, including India. Conventionally, the disease control in aquaculture has relied on the use of chemical compounds and antibiotics. The development of non-antibiotic and environmentally friendly agents is one of the key factors for health management in aquaculture. Consequently, with the emerging need for environmentally friendly aquaculture, the use of alternatives to antibiotic growth promoters in fish nutrition is now widely accepted. In recent years, probiotics have taken center stage and are being used as an unconventional approach that has numerous beneficial effects in fish and shellfish culture: improved activity of gastrointestinal microbiota and enhanced immune status, disease resistance, survival, feed utilization and growth performance. As natural products, probiotics have much potential to increase the efficiency and sustainability of aquaculture production. Therefore, comprehensive research to fully characterize the intestinal microbiota of prominent fish species, mechanisms of action of probiotics and their effects on the intestinal ecosystem, immunity, fish health and performance is reasonable. This review highlights the classifications and applications of probiotics in aquaculture. The review also summarizes the advancement and research highlights of the probiotic status and mode of action, which are of great significance from an ecofriendly, sustainable, intensive aquaculture point of view.     

海洋主要污染物对贝类及其环境的影响

为给海水贝类健康养殖提供依据,本文总结了近年国内外的报道,从氮、磷、重金属、石油类、有机氯农药等海洋污染物对贝类及其环境影响进行了归纳综述,发现由于特殊的取食方式,贝类体内的污染物含量较其它生物高,此外,同种污染物在不同种类贝类体内的积累也存在显著差异。因此,贝类养殖区的选择要比其他养殖区的选择更加谨慎,另外,也可以针对不同养殖海域的具体情况因地制宜地选择不同的养殖种类。     

Analysis of nutrient flows in integrated intensive aquaculture systems

This paper analyses nutrient conversions, which are taking place in integrated intensive aquaculture systems. In these systems fish is cultured next to other organisms, which are converting otherwise discharged nutrients into valuable products. These conversions are analyzed based on nitrogen and phosphorous balances using a mass balance approach. The analytical concept of this review comprises a hypothetical system design with five modules: (1) the conversion of feed nutrients into fish biomass, the “Fish-Biomass-Converter”; (2) the separation of solid and dissolved fish waste/nutrients; the “Fish-Waste-Processor”; (3) the conversion of dissolved fish waste/nutrients, the “Phototrophic-herbivore-Converter”; (4 and 5) the conversion of solid fish waste, the “Bacterial-Waste-Converter”, or the “Detrivorous-Converter”. In the reviewed examples, fish culture alone retains 20–50% feed nitrogen (N) and 15–65% feed phosphorous (P). The combination of fish culture with phototrophic conversion increases nutrient retention of feed N by 15–50% and feed P by up to 53%. If in addition herbivore consumption is included, nutrient retention decreases by 60–85% feed N and 50–90% feed P. This is according to the general observation of nutrient losses from one trophic level to the next. The conversion of nutrients into bacteria and detrivorous worm biomass contributes only in smaller margins (e.g. 7% feed N and 6% feed P and 0.06% feed N 0.03 × 10⁻³% feed P, respectively). All integrated modules have their specific limitations, which are related to uptake kinetics, nutrient preference, unwanted conversion processes and abiotic factors.     

采用化学氧化法降解贝类养殖水中扑草净残留的研究

为去除贝类养殖过程中残留的农药扑草净,研究了不同处理(正常、超声波震荡、紫外线照射和不同pH)条件下高锰酸钾、过氧化氢和次氯酸钠对扑草净的降解效果.结果显示,次氯酸钠对扑草净的降解率最高,其降解效果不受紫外线照射、超声波震荡以及水体pH变化的影响.高锰酸钾和过氧化氢对扑草净的降解率较低,超声波震荡和紫外线照射辅助处理对...     

The ecological role of bivalve shellfish aquaculture in the estuarine environment: A review with application to oyster and clam culture in West Coast (USA) estuaries

Aquaculture is viewed as a potential mechanism to meet the growing demand for seafood around the world. The future of bivalve shellfish aquaculture in the U.S. hinges on sustainable practices on the part of industry and a more consistent regulatory regime. Bivalve shellfish aquaculture is a recent practice relative to its history in other countries, beginning in the late 1800s along the U.S. West Coast where it is now well established with farm raised product utilizing land-based hatcheries and grow-out directly in numerous estuaries. Bivalve shellfish aquaculture can be viewed as a disturbance which modifies the estuarine system in three ways: 1) changes in material processes — bivalves process food and produce wastes; 2) addition of physical structure — aquaculture introduces the cultured organisms and in some cases a physical anchoring structure; and 3) pulse disturbances like harvest and bed maintenance disturb sediments, remove species in addition to the cultured organisms themselves, and change resource or habitat availability. In U.S. West Coast estuaries, water column and sediment nutrient concentrations are relatively high and influenced by large tidal exchange and proximity to deeper nearshore ocean waters where upwelling controls production during summer months. Bivalves are unlikely to influence material processes except at local bed scales in these systems, although estuary-wide effects could appear as the fraction of cultured area rises or in poorly flushed bays. Bivalve culture clearly modifies estuarine habitat at local community and at landscape scales and effects are most often evaluated against existing structured habitat in the form of submerged aquatic vegetation. Individual activities act as pulse disturbances and the recovery of eelgrass (Zostera marina) to pre-disturbance levels is variable (< 2 to > 5 years). The extent of disturbance depends on the aquaculture practice and the distribution of eelgrass reflects a balance of space competition, pulse disturbance and recovery, and is therefore at dynamic equilibrium on aquaculture beds. Structure provided by aquaculture appears functionally similar to eelgrass for small benthic infauna and mobile epibenthic fauna while use of aquaculture as habitat by larger more mobile invertebrates and fish depends on mobility and varies with life-history stage and taxon being evaluated. Scale seems a very important management consideration and further research at estuarine landscape scales, especially for habitat use by important invertebrates and fish, may prove useful in designing and implementing best management practices. Though local and short term effects from aquaculture are clearly evident in U.S. West Coast estuaries, bivalve aquaculture does not remove area from the estuary or degrade water quality like other anthropogenic influences, and thus has not been implicated in shifts to alternate states or reduced adaptive capacity of the larger ecological system.     

流沙湾浮游动物群落特征及与鱼贝养殖的关系

为了解流沙湾养殖活动对浮游动物群落的影响,于2015—2016年对流沙湾海区进行了夏(8月)、秋(11月)、冬(2月)、春(5月)4个季度的浮游动物调查,分析了浮游动物群落特征及其与环境因子的相关性。共记录浮游动物18大类119种、浮游幼体17种。浮游动物种类组成以桡足类(45种)和端足类(20种)为主,其次为毛颚类(15种)、水螅水母类(12种)、等足类(6种)等。十足目幼体(Decapod larvae)为春、夏两季的主要优势类群,亚强次真哲水蚤( Subeucalanus subcrassus)、微驼隆哲水蚤(Acrocalanus gracilis)为秋季主要优势种,夜光虫(Noctiluca scintillans )为冬季主要优势种。年均浮游动物丰度和生物量分别为151.53个·m^-3 和73.48 mg·m^-3 。多维尺度分析(nMDS)结果表明,除春季外,流沙湾内湾浮游动物群落组成与外湾差异明显。典范对应分析(CCA)显示,溶解氧、磷酸盐、透明度、温度和硝酸盐等环境因子是影响浮游动物优势种分布的主要因素。在流沙湾海区,鱼类小网箱的养殖活动在夏秋两季对浮游动物群落组成和结构影响较大;贝类养殖区的浮游动物的丰度和生物量明显降低,但浮游动物群落组成及多样性与其它采样点差异不大。     

桑沟湾贝类养殖区沉积碳库年汇入速率的高分辨率记录及其对人类养殖活动的响应

本研究对2014年取自桑沟湾贝类养殖区的柱状沉积物进行分析,测定每层沉积物中总碳(TC)、总有机碳(TOC)和总氮(TN)的质量分数,并计算总无机碳(TIC)、海源性有机碳(Cm)和贝壳无机碳(Shell-IC)的质量分数以及各组分碳在总碳中的贡献率,同时对其年汇入速率(BF)进行估算。结合210Pb测年法,研究近80年沉积碳库各种碳的年汇入速率的高分辨率记录,发现其中TC、TIC、TOC、Cm和Shell-IC的平均含量分别为1.09%、0.75%、0.34%、0.15%和0.06%。研究还发现,TIC是TC的主要形式,在1960—2010年的贡献率保持在60%以上。Cm的质量分数在2010年前无较大幅度的波动,但在2010年后显著增加,使得Cm/TC及TOC/TC也显著提升。Shell-IC在养殖活动开始后至2000年一直处于较低水平。各组分碳的年汇入速率在1960—2000年间随海水养殖活动呈现相应的变化,之后由于养殖规模和格局的调整,BFCm、BFTOC和BFTC显著升高,BFTIC降低,BFShell-IC先升高后降低。桑沟湾的海水养殖活动影响着贝类养殖区沉积碳库的组成和年汇入速率,碳库各组分的变动也体现出与之相应的变化。本研究详细描述了人类海水养殖活动在开始后的50年里对沉积碳库年汇入速率的影响特征,也为今后陆架海区水产养殖活动的合理规划提供参考。     

胶州湾贝类养殖区氮、磷污染现状及动态变化

依据2011年3、5、8、10月和1997～2010年5、8、10月水环境调查资料,对胶州湾贝类养殖区氮、磷污染现状及动态变化进行了分析与评价,并分析了海水富营养化的成因,可为赤潮的预测预警提供基础资料.结果表明,1)2011年胶州湾贝类养殖区氮、磷污染较为严重,除3月其含量符合标准要求外,5、8、10月均存在氮、磷污染,其中无机氮超标率为11.11％～100％,活性磷酸盐超标率为33.33％～66.67％,无机氮超标率均值高于活性磷酸盐.2)氮、磷污染程度具有明显的季节变化,以10月最重,8月次之,3月最轻.无机氮和活性磷酸盐污染指数均值分别为1.35和0.93,氮污染重于磷污染.3)氮、磷营养盐空间分布不均,贝类养殖区西部和东部海域氮、磷含量高于中部海域,空间分异程度为8月＞3月＞5月＞10月.4)海水富营养化程度较为严重,2011年3、5、8、10月富营养化站位所占比例为44.44％～100％,营养指数均值为1.09～6.99,海水富营养化严重程度依次为8月＞10月＞5月＞3月.5)2011年各调查月份养殖区海水中N/P比值为20.96～43.22,除5月部分测站N/P比值小于Redfield比值,其他3个月份N/P比值均大于Redfield比值,活性磷酸盐可能成为浮游植物生长的主要限制因子之一.6)氮、磷污染指数具有明显的年际变化,其中无机氮污染指数2008年最高,1997和2000年最低;活性磷酸盐污染指数1997年最高,2011年最低.7)海水富营养化成因复杂,径流携带大量氮、磷等营养物质入海和贝类养殖自身污染是造成胶州湾贝类养殖区海水富营养化的主因.近年胶州湾贝类养殖区氮、磷污染状况并无明显改善,海水富营养化依然严重,存在发生赤潮的可能性.     

福建围头湾贝类的养殖容量

通过对围头湾的叶绿素a含量、初级生产力、潮下带、潮间带和吊养区非养殖滤食性动物现存量、养殖贝类有机碳含量及其含壳重与鲜组织重的比值等模型参数的调查测定和检测分析,并参照邻近大嶝岛海域的浮游植物有机碳含量、养殖贝类的滤水率和参照附近深沪湾的生态效率,采用营养动态模型和沿岸海域能流分析模型估算了该海域贝类生态容量,进而扣除野生滤食性动物现存量,估算贝类养殖容量；同时应用方建光模型估算贝类的养殖容量；还采用统计分析法估算贝类及其各养殖品种的适养面积,目的在于控制该海域贝类的养殖量和对各种贝类养殖量进行优化配置。3种模型估算的贝类养殖容量分别为111 720 t,508 246×10~4 ind；112 072 t,509 849×10~4 ind和114 504 t,520 789×10~4 ind,平均112 765 t,512 991 ind；适养面积为3 905 hm~2,其中牡蛎2 956 hm~2,缢蛏359 hm~2,菲律宾蛤仔489 hm~2,翡翠贻贝11 hm~2,凸壳肌蛤90 hm~2。1999年贝类养殖总面积1 894 hm~2,尚有2 011 hm~2可再扩大养殖的潜力。     

光合细菌大棚富集培养技术在养鱼中的应用

光合细菌作为环保型饲料添加剂 ,具有营养丰富、净化水质、防治鱼病、维持水体生态平衡的作用。采用大棚简易富集培养法 ,可大量培养光合细菌 ,此技术成本低、效益高、操作简单 ,适于在北方淡水养鱼中推广使用。     

福建诏安湾贝类养殖容量的研究

通过现场对诏安湾叶绿素a含量、初级生产力、生态效率、浮游植物有机碳含量、养殖贝类有机碳含量及其含壳重与鲜组织重比值、养殖贝类和野生滤食性动物滤水率、潮间带和潮下带及吊养区附着滤食性动物现存量等的调查获得模型参数,应用营养动态模型、沿岸能流模型估算贝类生态容量,进而扣除野生滤食性动物现存量形成贝类的养殖容量,同时采用贝类能量收支模型估算贝类养殖容量。3种模式估算的贝类养殖容量分别为58469t,288260×104ind;60275t,297167×104ind;61532t,30336×104ind;平均60092t,296263×104ind。并且采用统计分析法估算贝类及其各品种的适养面积。贝类适养总面积为2755hm2,其中缢蛏25hm2,牡蛎1560hm2,翡翠贻贝215hm2,菲律宾蛤仔120hm2,泥蚶30hm2,凸壳肌蛤95hm2,波纹巴非蛤710hm2。     

流沙湾贝类养殖海域环境质量评价

根据2008年5月至2009年2月对流沙湾贝类养殖海域渔业环境综合调查的数据,对海水环境质量的现状进行了分析讨论,综合评价了海水有机污染和营养水平,并对沉积物重金属的累积程度和潜在生态危害进行了评价。结果表明,调查海域盐度、溶解氧（DO）、化学耗氧量（COD）、无机氮（DIN）和活性磷酸盐（PO4^3-）呈季节性变化,其中盐度和DIN的季节变化与该海域季节性降水有关,而DO、COD和PO4^3-的变化与浮游植物和贝类养殖有关。评价结果显示,流沙湾海域水质清洁,海水氮（N）营养盐过剩而磷（P）贫乏,属于P限制型中等富营养化海域;调查海域沉积物中砷（As）和铅（Pb）处于无污染状态,汞（Hg）和镉（Cd）处于轻度污染,铜（cu）在部分区域处于中度污染状态;Ca、Pb、As、锌（Zn）和铬（Cr）的潜在生态危害属于轻微,Hg和Cd的潜在生态危害处于中等强度。     

渤海海域唐山贝类养殖区腹泻性和麻痹性贝类毒素的监测与风险评估

为监测渤海海域唐山贝类养殖区贝类毒素的污染情况,防止食用贝类中毒事件发生,于2019年10月—2020年9月间,每月持续在渤海海域唐山贝类养殖区采集四角蛤(Mactra veneriformis)、菲律宾蛤仔(Ruditapes philippinarum)、脉红螺(Rapana venosa)、牡蛎(Crassostrea gigas)、青蛤(Cyclina sinensis)、文蛤(Meretrix meretrix)和硬壳蛤(Mercenaria mercenaria) 7种经济贝类样品,采用高效液相色谱–串联质谱(HPLC-MS/MS)法测试了5种腹泻性贝类毒素(diarrhetic shellfish poisoning, DSP)和14种麻痹性贝类毒素(paralytic shellfish poisoning, PSP)。结果显示,在7种经济贝类样品中均未检出DSP。检出的PSP成分包括石房蛤毒素(Saxitoxin, STX)、膝沟藻毒素1 (Gonyautoxin 1, GTX 1)、膝沟藻毒素2 (Gonyautoxin 2, GTX 2)和脱氨甲酰基膝沟藻毒素3 (Ddecarbamoy l gonyautoxin 3, dcGTX 3),其中,GTX 1含量最高且最高值为537.95 μg/kg。不同季节贝类毒素蓄积含量有一定差异,PSP主要集中在4月检出。菲律宾蛤仔、牡蛎、文蛤和硬壳蛤中PSP的检出率分别为11.76%、47.06%、5.90%和8.82%,其他贝类均未检出。PSP总量均低于欧盟及中国的食用安全限量标准800 μg STXeq/kg。应用风险熵值法和点评估法进行食用安全风险评估,显示风险熵值和暴露风险指数均在安全范围内,结果表明,渤海海域唐山贝类养殖区7种经济贝类不存在食用安全风险。     

Cage culture development and its role in aquaculture in China

Abstract. This paper is divided into four parts. First, history: cage culture has long been practised. The origin of cage culture world-wide should be regarded as the middle reaches of the Yangtze River, China, in the Sung Dynasty. Second, characteristics of cage culture in China. Third, influence: development of open-water fisheries is actively promoted in lakes, reservoirs and rivers. More kinds of water bodies have been employed for this purpose. Marine cages have also rapidly developed. Finally, discussion and conclusions. Cage culture is a modern development of aquaculture which has changed the long-established, fish-farming structures and, to a great extent, pushed forward fisheries development in China. Cage culture is typically characterized by intensive farming, running-water culture, high yield and great efficiency. It is generally accepted that cage culture will actively play an increasingly important role in international aquaculture.     

重视锦鲤养殖中的营养需要问题

优美的体形和体色是对锦鲤进行评价及购买时挑选锦鲤的重要特征,也是养鱼者应该首先考虑的。饲养者给锦鲤提供非常均衡的饮食,目的是为了让     

贝类养殖吊笼水动力特性的实验研究

通过模型实验的方法分别探讨了规则波和均匀流作用下贝类养殖吊笼的水动力特性,并分析了贝类养殖密度对吊笼受力的影响。在波浪作用下,基于莫里森方程,通过最小二乘法计算水动力系数C_d和惯性力系数C_m值;在水流作用下,利用简化莫里森公式反推出C_d值;分析了Kc数、雷诺数Re和养殖密度对C_d和C_m的影响。结果显示:吊笼的运动幅度及受力随着波高、周期及流速的增大而增大;随着贝类养殖密度的增大,吊笼受到的水平力逐渐增大,而吊笼的运动幅度逐渐减小;在波浪效应下,随着Kc数、Re的增大,C_d有略微增大趋势,而C_m则先增大后趋于常数;在水流作用下,C_d值随着雷诺数Re的增大无显著变化;在同一工况下,C_d随着贝类养殖密度的增加而增大,而C_m相应减小。研究表明,本实验得出的吊笼水动力系数可作为计算吊笼波浪力和流阻力时的取值参考。     

Effects of off‐bottom shellfish aquaculture on winter habitat use by molluscivorous sea ducks

• 1. Shellfish farming is an expanding segment of marine aquaculture, but environmental effects of this industry are only beginning to be considered.
• 2. The interaction between off‐bottom, suspended oyster farming and wintering sea ducks in coastal British Columbia was studied. Specifically, the habitat use of surf scoters (Melanitta perspicillata) and Barrow's goldeneyes (Bucephala islandica), the most abundant sea duck species in the study area, was evaluated in relation to natural environmental attributes and shellfish aquaculture.
• 3. The extent of shellfish farming was the best‐supported habitat variable explaining variation in surf scoter densities, and the only habitat attribute from the considered set that was a strong predictor of Barrow's goldeneye densities. In both cases, the findings indicated strong positive relationships between densities of sea ducks and shellfish aquaculture operations. These relationships are presumably the result of large numbers of wild mussels (Mytilus trossulus) that settle and grow on aquaculture structures and are preferred prey of these sea ducks.
• 4. Previous work has shown that aquaculture structures provide good conditions for recruiting and growing mussels, including refuge from invertebrate predators, which in turn provides higher densities of higher quality prey for sea ducks than available in intertidal areas. This offers a rare example in which introduction of an industry leads to positive effects on wildlife populations, which is particularly important given persistent declines in numbers of many sea ducks.

Copyright © 2008 John Wiley & Sons, Ltd.