Biophysical models for Japanese scallop, Mizuhopecten yessoensis, aquaculture site selection in Funka Bay, Hokkaido, Japan, using remotely sensed data and geographic information system

Scallop aquaculture has grown to become the most successful marine shellfish farming venture in Japan. To ensure long-term sustainability of scallop production, suitable sites need to be selected. This study was conducted to identify the most suitable sites for hanging culture of Japanese scallop (Mizuhopecten yessoensis) based on measured biophysical parameters and modeled using geographic information system (GIS) models. Four biophysical parameters that influence Japanese scallop aquaculture in Funka Bay were selected: sea temperature, food availability (chlorophyll-a), suspended solid, and bathymetry. The SeaWiFS and MODIS images were used to extract most of these parameters. A series of GIS models was developed to identify suitable sites for scallop culture using a multi-criteria evaluation (MCE) known as weighted linear combination. Suitability scores were ranked on a scale from 1 (least suitable) to 8 (most suitable), and about 83% of the total potential area with bottom depths less than 60 m had scores of 7 and 8. The final model outputs were compared with field verification data and found to be consistent. Local sensitivity analysis was used to test the robustness of the model output. Based on this analysis, the order of importance of the variables affecting the model was as follows: suspended solid > chlorophyll-a > sea temperature.     

Geographic Information System as an instrument to determine suitable areas and identify suitable zones to the development of emerging marine finfish farming in Brazil

Worldwide, the availability of suitable areas for aquaculture has become a significant concern. In Brazil, the former Ministry of Fisheries and Aquaculture (MPA) has begun to promote discussions and plan meetings on Local Mariculture Development Plans (PLDMs): a planning tool for the establishment of parks and aquatic areas. However, hundreds of groups and individuals still practice aquaculture awaiting a definitive license. This study aimed to serve as a tool to identify suitable sites for the installation of cobia cage farming and also to contribute to the PLDM zoning process. We created 27 criterion maps for marine fish farming. Their individual weights were assigned based on the best judgment of technicians, researchers and other stakeholders using the pair‐wise comparison method. The criteria and their weights were combined using multi‐criteria decision rules, and a final map according to suitability was derived by reclassification. Of the total area, 54,663 ha (14%) were composed of restrictions, and 341,083 ha (86%) were found useful; of which <1% is considered top score. Even so, these are more than enough to ensure the growth of activity. In Rio de Janeiro state, two bays have suitable areas to marine fish culture development. To ensure the sustainability of marine fish farming, we suggested the adoption of limited production areas based on assimilation and production capacity. Through this methodological approach, it was possible to identify suitable areas for cobia farming development. Additionally, the results may serve as a useful tool on which the PLDM can be based on.     

Connectivity of the bay scallop (Argopecten irradians) in Buzzards Bay,Massachusetts, U.S.A.

The harvest of bay scallops (Argopecten irradians) from Buzzards Bay, Massachusetts, U.S.A. undergoes large interannual fluctuations, varying by more than an order of magnitude in successive years. To investigate the extent to which these fluctuations may be due to yearly variations in the transport of scallop larvae from spawning areas to suitable juvenile habitat (settlement zones), a high‐resolution hydrodynamic model was used to drive an individual‐based model of scallop larval transport. Model results revealed that scallop spawning in Buzzards Bay occurs during a time when nearshore bay currents were principally directed up‐bay in response to a persistent southwesterly sea breeze. This nearshore flow results in the substantial transport of larvae from lower‐bay spawning areas to settlement zones further up‐bay. Averaged over the entire bay, the spawning‐to‐settlement zone connectivity exhibits little interannual variation. However, connectivities between individual spawning and settlement zones vary by up to an order of magnitude. The model results identified spawning areas that have the greatest probability of transporting larvae to juvenile habitat. Because managers may aim to increase scallop populations either locally or broadly, the high‐connectivity spawning areas were divided into: (i) high larval retention and relatively little larval transport to adjoining settlement areas, (ii) both significant larval retention and transport to more distant settlement areas, and (iii) little larval retention but significant transport to distant settlement areas.     

小竹山岛海洋牧场区营养盐分布特征及增养殖适宜性探究

营养盐作为海水生物的基本生源要素,其含量与分布显著影响渔业资源分布与渔业活动。为了探究海洋牧场生态环境分布状况,并为海洋牧场的开发管理提供科学指导,于2017年12月—2018年9月对小竹山岛海洋牧场区进行4个航次的季度调查,分析并讨论了该海区营养盐分布特征,并针对虾夷扇贝(Patinopecten yessoensis)和深水网箱增养殖活动,选取海水营养水平指数、叶绿素a浓度、温度、盐度、水深和底质类型等指标,对增养殖适宜性进行了探究。结果显示,活性磷酸盐(DIP)浓度为冬季>夏季>秋季>春季,浓度值分别为0.032、0.021、0.017和0.015 mg/L。无机氮(DIN)浓度为秋季>冬季>夏季>春季,浓度值分别为0.26、0.21、0.20和0.18 mg/L。DIP和DIN浓度在4个季节间差异明显,但季节内分布均匀。受到地形坡度和人工鱼礁投放的影响,在人工鱼礁投放区域的中下层水体有较高的营养盐浓度。增养殖适宜性结果显示,虾夷扇贝增养殖适宜性指数在冬季和夏季较高,适宜在海洋牧场西部区域进行增养殖活动。深水网箱增养殖适宜性指数在夏季和秋季较高,也适宜在西北区域进行增养殖活动。由于人工鱼礁投放改善了生态环境,除西北海域外,在人工鱼礁投放区域附近出现较高的增养殖适宜性指数。海水营养盐分布与增养殖活动适宜性评价可为提高海洋牧场增殖效率、促进可持续发展及开发提供科学依据与参考。     

两个海区栉孔扇贝感染AVNV的比较分析

急性病毒性坏死病毒(acute viral necrosis virus,AVNV)是一种能导致栉孔扇贝大规模死亡的DNA病毒,研究通过检测不同养殖模式和不同苗种来源的栉孔扇贝样本携带AVNV的情况,以寻找合理的养殖模式和苗种,降低疾病的发生。以扇贝单一养殖的青岛流清河海区和贝藻间养的荣成桑沟湾海区为采样点,每月(2010年3月—2011年4月)定期采集2个海区野生苗养殖和人工苗养殖的栉孔扇贝样品各10只,共得到扇贝样本480只。取扇贝外套膜组织,提取DNA,采用巢式PCR检测扇贝感染AVNV的情况,并对2个海区2类栉孔扇贝AVNV感染率进行比较。结果显示,在2个海区的2类栉孔扇贝体内均检测到AVNV,流清河海区野生苗和人工苗养殖栉孔扇贝AVNV感染率分别为21.1%和18.9%,桑沟湾海区2类扇贝AVNV感染率分别为11.1%和5.6%;2个海区AVNV感染扇贝均集中在7、8月份,其中,流清河海区最高可达80%,桑沟湾海区最高仅40%。研究表明,贝藻间养和选用人工苗能有效减少AVNV对养殖扇贝的感染,是控制养殖扇贝发病死亡的有效措施。     

Annual variation in otolith increment widths of walleye pollock (Gadus chalcogrammus) larvae in Funka Bay,Hokkaido, Japan

To clarify relationships between year‐class strength and larval growth of walleye pollock (Gadus chalcogrammus), and oceanographic conditions in the Pacific stock off Hokkaido and Tohoku, Japan, we undertook conductivity/temperature/depth (CTD) observations and investigated larval densities, larval otolith increment widths and larval prey densities (of copepod nauplii) of the 2008, 2009, 2010 and 2011 yr classes in Funka Bay. Oyashio Coastal Water (OCW) flowed into the bay in late February in 2008, 2010 and 2011, and the mean water temperatures decreased to 1.9–3.1 °C in March. OCW was not observed in 2009, and it was warm in late February (≥3.4 °C). Increment widths of lapillar otoliths during the yolk‐sac stage were wide in 2009 and 2011, medium in 2010 and narrow in 2008. Increment widths during the first‐feeding stage tended to become wider as the hatch month progressed, and the annual variation during the first‐feeding stage was larger than that of the yolk‐sac stage. The densities of the primary food for the larvae were high in 2008 when larval increment widths were narrowest, so the effect of prey abundance on larval growth appeared to be small. The ranking of the larval abundance in March was nearly coincident with that of the increment width during the larval stage. We, therefore, suggest that the larval growth rate is associated with the mortality rate and that the growth–mortality hypothesis may be applicable to walleye pollock in Funka Bay. Feeding success under warm water conditions may be an important factor that contributes towards high growth rates.     

Annual changes in macrobenthos abundance in Funka Bay,Japan

The temporal variation in macrobenthos abundance was studied in Funka Bay in the periods 2001–2004 and 2007–2010. Dissolved oxygen just above the sea floor of the basin was lower and ignition loss at the level of the sea floor was higher in 2007–2010 than in 2001–2004. Macrobenthic species were categorized into three groups: long-lived species, sedental polychaeta Notomastus latericeus, and short-lived species. Ignition loss was the most influential factor affecting macrobenthos abundance as this variable restricts the recruitment of macrobenthos. The abundance of both long-lived species and N. latericeus was lower between 2007 and 2010 than between 2001 and 2004. Supplementation of oxygen from outside the bay by the Tsugaru Warm Current may be an important factor impacting the increase in the abundance of long-lived species. The abundance of N. latericeus barely increased between 2007 and 2010, possibly because dissolved organic matter, which is their food item, may have become limited due to a narrow chink between sediments with eutrophication. The abundances of short-lived species did not differ between the periods 2001–2004 and 2007–2010 due to the organisms having a low tolerance to hypoxia. The current conditions in Funka Bay are on the verge of turning the bay into an azoic zone.     

浮筏养殖虾夷扇贝的自然稀疏效应

为了研究虾夷扇贝浮筏养殖自然稀疏效应和科学养殖密度,2009年8月—2010年7月,对不同密度梯度的3个贝龄虾夷扇贝进行浮筏养殖现场实验。在自然稀疏条件下,逐月调查浮筏养殖不同贝龄的虾夷扇贝壳长生长、湿重增长和累计死亡率,并估算了适宜的扇贝浮筏养殖密度。结果表明,在不同养殖密度条件下,3 个贝龄扇贝周年壳长生长都没有显著差异;1龄贝壳长增长最快,年均增长29.53 mm;2龄贝壳长年均增长23.50 mm;3龄贝壳长增长较慢,年均增长15.47 mm;3个贝 龄扇贝周年湿重增长都没有显著差异,3龄贝和2龄贝湿重增长较快,3龄贝的年均增长约54.07 g,2龄贝的年均增长约37.80 g,1龄贝的年均增长约14.69 g;2 龄贝、3龄贝各养殖密度梯度之间累计死亡率都没有显著差异,3龄贝死亡率介于76.30%～83.33%,2龄贝死亡率介于88.89%～91.78%,养殖密度为150个/层的1龄贝与80个/层和50个/层的1龄贝累计死亡率差异显著。依据自然稀疏模型,浮筏养殖适宜密度3龄贝为4～5个/层;2龄贝为8～16个/层,1龄贝为29～124个/层。     

Multi-criteria evaluation approach to GIS-based land-suitability classification for tilapia farming in Bangladesh

Site selection is a key factor in any aquaculture operation, because it affects both success and sustainability. It can, moreover, solve conflicts between different activities, making rational use of the land. This study was conducted to identify suitable sites for development of Nile tilapia (Oreochromis niloticus) farming in Sitakunda Upazila (sub-district), Bangladesh, using GIS-based multi-criteria evaluation of water and soil quality, topography, infrastructure and socio-economic factors. ASTER image and eighteen thematic layers were analyzed using ENVI and ArcView software to identify the suitable areas for tilapia farm development. A constraint layer was used to exclude areas from suitability maps that cannot be allowed to implement tilapia farming. A series of GIS models were developed to identify and prioritize the most suitable areas for tilapia farming. The output of the model clearly indicates the location and extent of tilapia farming areas on different suitability scales, i.e. most suitable (7,744 ha), moderately suitable (2,479 ha), and not suitable (838 ha). Model outputs were assessed against field verification data, and were consistent. Because existing aquaculture covers only 1,540 ha of land in the study area, the potential for expanding tilapia farms should take into consideration socio-political and environmental issues. The results are encouraging in terms of tilapia culture development and suggest that grassland–agriculture areas could be used for sustainable development of tilapia farming to diversify the economic activities of rural communities.     

中国深远海养殖发展方式研究

在渔业转型发展进程中,发展深远海养殖是突破生态环境和自然资源约束性挑战,实现新时期中国海水养殖业可持续发展的战略方向。基于联合国粮食及农业组织(FAO)关于深远海养殖发展的定义,结合中国海水养殖业发展水平和海域条件,对中国深远海养殖概念进行了界定。提出养殖品种选择、养殖系统构建、养殖海域规划是关系深远海养殖产业稳步有序发展的重要因素。在养殖品种选择方面,应重点考虑经济潜力、适应水温和养殖技术;在养殖系统构建上,分析比较了不同养殖系统应用于深远海养殖的适宜性、安全性和经济性;在养殖海域规划方面,应重点考虑养殖排放、环境承载力和海域条件。     

Behavioural interactions of seabirds with suspended mussel longlines

Increased abundances of a number of seabird species have been found in areas of mussel longline aquaculture (compared to control sites) in a recent study at Bantry Bay, southwest Ireland. The aim of this study was to investigate whether this form of mussel aquaculture also affects the activity budgets and foraging behaviour of these seabirds. Scan-sampling was used to compare seabird activity budgets between three areas of mussel longline aquaculture and three control sites. Foraging activities of Great-Northern Divers Gavia immer, an Annex 1 species under the Euopean Union's Birds Directive, were also compared between sites using focal sampling. The behaviour of gulls (Larus sp.), Cormorants Phalacrocorax carbo, Shags Phalacrocorax aristotelis and Great-Northern Divers (but not auks, Alcidae) differed significantly between areas of mussel aquaculture and control sites in this study. Mussel suspension buoys were heavily utilized by gulls, cormorants and shags as safe perching platforms for preening activities. Gulls also fed extensively on epifauna attached to the buoys. Great-Northern Divers spent more time snorkelling (head submerged in search of food) in mussel sites than in the control sites, however dive duration and visible foraging success rates did not differ significantly between sites. Overall, the environmental impact of mussel suspension culture appears to be positive or neutral on marine bird species occurring at this study site.     

Geographical information systems-based models for offshore floating marine fish cage aquaculture site selection in Tenerife, Canary Islands

The present study focuses on the development of a standard methodology for selection of suitable sites for offshore (exposed) marine fish‐cage farming (floating cages) of seabream (Sparus aurata) and seabass (Dicentrarchus labrax) in an island environment, using Tenerife as an example. Site selection is a key factor in any aquaculture operation, affecting both success and sustainability and can solve conflicts between different activities, making a rational use of the coastal space. Site selection was achieved by using geographical information systems (GIS)‐based models and related technology to support the decision‐making process. The framework for spatial multicriteria decision analysis used in this study began with a recognition and definition of the decision problem. Subsequently, 31 production functions (factors and constraints) were identified, defined and subdivided into eight submodels. These were then integrated into a GIS database in the form of thematic layers and later scored for standardization. At this stage, the database was verified by field sampling to establish the quality of data used. The decision maker's preferences were incorporated into the decision model by assigning weights of relative importance to the evaluation under consideration. These, together with the thematic layers, were incorporated using multicriteria evaluation techniques and simple overlays to provide an overall assessment of possible alternatives. The integration, manipulation and presentation of the results by means of GIS‐based models in this sequential and logical flow of steps proved to be very effective for helping the decision‐making process of site selection. Tenerife has very favourable environmental conditions for culture of marine fish and there are no totally unsuitable sites for cage farming identified in this study. On the other hand, there are few very suitable sites (high scores) either, principally due to the heavy use of the coastline and the conflicts between different users. From the 228 km² of available area for siting cages in the coastal regions with depth less than 50 m, the total area suitable for siting cages (scores 6–8) was 37 km². There are only 0.51 km² of very suitable areas (score 8) and approximately 5.37 km² of suitable (score 7), most of these being located in the southeast of the island. These relatively small areas of suitability should be put into the context of the wider use of the coastal environment around Tenerife.     

Polyculture of sea scallops (Placopecten magellanicus) suspended from salmon cages

Commercial and developmental operations for the culture of the seascallop, Placopecten magellanicus, are present in AtlanticCanada and New England. In an experiment designed to examine the commercialfeasibility of polyculture of scallops with Atlantic salmon(Salmo salar), we measured growth andsurvival of sea scallops grown in suspension at two salmon aquaculture sites innortheastern Maine (Johnson Cove (JC) and Treats Island (TI)). Sea scallop spatwere grown in pearl nets and deployed on drop lines containing ten nets inAugust 1994. One drop line of ten nets was sampled about every four months andscallops were counted, measured and weighed. Scallop tissues were also analysedfor paralytic shellfish toxins (PSP). The maximum level of PSP recorded duringthe study was 1174 g STX equiv.·100 gtissue^–1 (excluding adductor muscle weight). After one year,shell heights were 53.6 and 56.4 mm, growth rates were 0.11 and0.12 mm per day and wet adductor muscle weights were 3.3 and 4.1g (TI and JC, respectively). These growth rates were comparable tosea scallops grown in suspension culture to a nearby scallop aquaculture siteand other areas in Atlantic Canada. Reduced rates of survival were found duringthe latter part of the experiment and were attributable, in part, to heavyfouling, predators and high stocking density. The potential for supplementalincome, diversification of the salmon aquaculture industry, and feasibility ofculturing scallops at adjacent sites to salmon operations does exist.     

大亚湾海域2009—2015年氮、磷营养盐时空分布及富营养化评价

为了解大亚湾海域海水中氮(N)、磷(P)营养盐的时空分布情况及富营养化程度,于2009年4月和5月、2010年5月和6月、2012年2月、2015年1月和2月对大亚湾海域进行海水采样监测。结果表明,大亚湾海域不同功能区无机氮(DIN)和活性磷酸盐(PO4-P)浓度总体上为先增后降的趋势,DIN和PO4-P的时空分布由于受陆源污染、海水养殖等影响,浓度呈近海岸向远海岸递减的趋势。潜在富营养化评价表明,大亚湾海域整体上经历了由贫营养转为中度营养再转为贫营养的过程,其中一类功能区长年处于贫营养状态。总体上大亚湾平均氮磷比(N/P)接近或小于Redfield比值。     

几种养殖扇贝微卫星标记的研究进展

我国扇贝养殖规模占世界首位，栉孔扇贝( Chlamys farreri ) 、华贵栉孔扇贝( Chlamys nobilis ) 、虾夷扇贝( Patinopecten yessoensis) 和海湾扇贝( Argopecten irradians ) 是4 种主要养殖扇贝种类。本文主要概述我国4种主要养殖扇贝微卫星标记开发现状以及在遗传多样性分析、遗传图谱构建、物种鉴定等方面取得的研究成果和应用进展，为微卫星标记在扇贝类遗传学研究提供基础资料。     

The effects of epibionts and predators on the growth and mortality rates of Argopecten purpuratus cultures in southern Chile

Epibiont and predator effects on the growth and mortality of the northern scallop Argopecten purpuratus were evaluated in cultures in southern Chile.The most common epibionts were bryozoans, hydrozoans and algae in both study sites, Metri Bay (41°36; 72°43W) and Chidhuapi Channel (41°49S; 73°05W).After 12 months of culture in pearl nets and lantern nets, the scallops size did not show statistically significant differences in cultures with and without epibionts in both study sites nor were there differences in the growth either with or without the presence of predators (decapod crustaceans). The growth rate was higher in Chidhuapi Channel than in Metri Bay.Mortality was concentrated in the initial phase of culture in pearl nets. During the culture phase in lantern nets, the mortality rate was lower than 3%. The mortality rate in scallops with epibionts was higher than when these were removed in the culture phase in pearl nets. In Metri Bay the mortality rate with predators was higher than without predators. Epibionts and predators did not affect mortality in the culture phase in lantern nets.Epibionts and predation are important factors in the early mortality of scallops and therefore in the success of culture. Epibiosis, however, is not important in scallop growth in southern Chile. This is related to the composition of the epibionts and to the low temperatures which probably limit the growth of algae and invertebrates.     

应用DGGE技术研究扇贝养殖海域微型真核浮游生物多样性

为了研究扇贝养殖海区微型真核浮游生物群落多样性,明确养殖扇贝发病时期高丰度微型真核浮游生物种类,探讨微型真核浮游生物与栉孔扇贝急性病毒性坏死病毒(acute viral necrosis virus,AVNV)水平传播的可能关系。于2009年和2010年从青岛流清河湾扇贝养殖海区采集了9个月份的海水样品,经25和3 μm的滤膜过滤收集海水中3~25 μm的浮游生物,扩增18S rDNA可变区序列,并利用变性梯度凝胶电泳(denaturing gradient gelelectrophoresis,DGGE)技术对扩增序列进行分离以分析微型真核浮游生物多样性。结果表明,该养殖海区微型真核生物包括甲藻、纤毛虫、眼虫、定鞭藻、硅藻、盘蜷虫、隐藻、领鞭毛虫、变形虫和Cercozoan,其中甲藻类和纤毛类生物的最高相对丰度分别达41.0%和38.2%,是海区的优势种类。各月份DGGE谱带聚类分析结果表明,2009年6、7、8、9月份浮游生物群落组成较为相似。中肋骨条藻在扇贝发病前后均有分布。结合相关扇贝AVNV已有的研究结果,研究认为中肋骨条藻是AVNV水平传播的参与者之一,但海区中广泛分布的甲藻和纤毛虫与AVNV传播的关系还有必要进一步研究。     

福建近海若干个拟投放深水网箱海湾理化环境调查与评估

根据2000和2001年福建主要港湾调查所获得的海洋水文和海洋化学环境资料，对拟投放深水抗风浪网箱海域的海水理化因子作了较详细的分析研究，以评估该海域是否适合于投放深水网箱。结果表明，三都澳、官井洋、东吾洋、罗源湾、福清湾、兴化湾，湄州湾和东山湾水深在25m以上，湾外有岛屿屏障，环境隐蔽、水流稳定，水温、盐度和透明度有显著的季节变化，pH和DO符合国家渔业水质标准，COD一般符合一类海水水质标准，局部海域达到二类海水水质标准，IN、PO3-P一般符合二类海水水质标准，在秋季有些港湾达到三类海水水质标准。从理化环境的角度分析，上述海湾可作为投放深水网箱之场所。     

Resistance of Dermo in eastern oysters, Crassostrea virginica (Gmelin), of North Carolina but not Chesapeake Bay Heritage

Growth, intensity of Perkinsus marinus (Levine) infection, and survival of synchronously spawned North Carolina (NC) and Chesapeake Bay‐heritage (CB) oysters, Crassostrea virginica (Gmelin) were evaluated under standard tray culture conditions at several sites in both regions (Wye River, Maryland; Mobjack Bay, Virginia; Pamlico River, NC and Bogue Banks, NC). Infection prevalence reached 100% in oysters held at all high‐ and moderate‐salinity sites, at which time the CB strain ceased to grow. Shortly after growth ceased, CB oysters exhibited mortality that rapidly progressed to 100%. Unlike the CB strain, growth continued in the NC strain despite high P. marinus prevalence. When mortality did occur in the NC strain, at a reduced rate of 37–40%, it was associated with higher intensity of P. marinus than the infection intensity correlated with death of CB oysters. At the low‐salinity site in NC, P. marinus infection persisted at low weighted prevalence throughout the latter portion of the culture period but was not associated with mortality of either strain. These trends in growth and disease resistance for the two strains demonstrate that aquaculture performance is related to the level of disease resistance in oyster strains, salinity of water in growing areas and virulence of P. marinus.