Distribution of the introduced cyprinid herpesvirus 3 in a wild population of common carp, Cyprinus carpio L.

Cyprinid herpesvirus 3 (CyHV-3), which causes a lethal disease in common carp, Cyprinus carpio L., and koi, C. carpio koi , first occurred in Lake Biwa, Japan in 2004. To elucidate distribution of CyHV-3 in a wild common carp population, we conducted a PCR survey of CyHV-3 among such fish in Lake Biwa in 2006. Only 6% (1/18) of the common carp smaller than 300 mm were positive with PCR, whereas 31% (18/58) of fish larger than 300 mm were positive. To evaluate their past exposure to CyHV-3 infection based on the presence of antibodies, we also measured the levels of serum anti-CyHV-3 antibodies in the carp, using an enzyme-linked immunosorbent assay. None (0/26) of the fish smaller than 300 mm was positive for the antibodies, whereas 54% (33/61) of fish larger than 300 mm were positive. Of the antibody-positive individuals, 44% (14/32) were also positive by PCR strongly suggesting that wild common carp that survived infection become CyHV-3 carriers. Five individuals were positive by PCR but negative for antibodies indicating that their infection with CyHV-3 had occurred recently. These results suggest that transmission of CyHV-3 from carriers to naïve common carp is still occurring in Lake Biwa.     

Koi herpesvirus epizootic in cultured carp and koi, Cyprinus carpio L., in Taiwan

Koi herpesvirus (KHV) poses a significant threat to cultured koi and common carp, both Cyprinus carpio L. Since the first reported case in Israel in 1998, KHV has rapidly spread worldwide. This study investigates the spread of KHV to Taiwan by collecting 49 cases of suspected common carp and koi infections from 2003 to 2005 for analysis. Clinical signs included lethargy, anorexia, increased respiratory movements and uncoordinated swimming. Hyperaemia, haemorrhage on body surface and necrotic gill filaments were recorded. Gill epithelial hyperplasia, necrosis and eosinophilic intranuclear inclusion bodies were observed by histological examination, while virions were detected using transmission electron microscopy. By detecting the presence of the KHV thymidine kinase (TK) gene and the KHV 9/5 gene using polymerase chain reaction (PCR), 37 cases were identified as KHV-positive, and the cumulative mortality of infected fish was 70-100%. Positive cases showed identical sequences for the genes analysed, implying that they were of the same origin. For the KHV 9/5 gene sequence, these cases exhibited 100% identity with the Japanese strain (TUMST1, accession number AP008984) and 99% identity with the Israeli (KHV-I, DQ177346) and US (KHV-U, DQ657948) strains. Additionally, a loop-mediated isothermal amplification (LAMP) assay was performed and found to be more sensitive than PCR tests, suggesting its potential use as a rapid diagnostic method for KHV. This is the first epidemiological study of KHV infection in cultured common carp and koi in Taiwan.     

抗鲤疱疹Ⅱ型病毒卵黄抗体制备及其功能鉴定

为制备抗鲤疱疹Ⅱ型病毒(CyHV-2)的卵黄抗体,探索防治异育银鲫(Carassius auratus gibelio)鳃出血病的新方法和途径,本研究利用原核表达系统产生具免疫原性的重组CyHV-2-ORF72衣壳蛋白,纯化后免疫蛋鸡;二次免疫后采用间接ELISA法抽检免疫蛋的特异性卵黄抗体(IgY)含量,收集抗体效价...     

Detection of Koi herpesvirus: impact of extraction method,primer set and DNA polymerase on the sensitivity of polymerase chain reaction examinations

Since virus isolation is seldom successful, KHV infection is commonly detected by PCR examination. A number of different PCR assays have been described in recent years. However, at present no commonly accepted PCR method is used amongst different laboratories. The aim of this study was to check if the examination of infected fish by different PCR methods yielded comparable results. We used tissue samples of three KHV‐infected koi, one KHV‐infected common carp, one KHV‐infected goldfish and one non‐infected common carp. DNA was extracted with DNAzol Reagent, High Pure PCR Template DNA Preparation Kit and QIAamp DNA Mini Kit. The DNA was tested by PCR with different combinations of published primer sets –KHV‐F and ‐R, KHV‐Gray‐2F and ‐2R and KHV‐TKf and ‐TKr – plus different DNA polymerases – a standard Taq DNA polymerase, a Platinum (hotstart) Taq DNA polymerase and a Platinum (hotstart) Pfx DNA polymerase with proofreading activity. The different extraction methods produced DNA solutions with different yields of DNA and different degrees of homogeneity. Also, the sensitivity of the PCR depended on the choice of the primer set and polymerase. Not all infected fish could be identified with all methods; there were large differences in the sensitivity between methods.     

Susceptibility of koi × crucian carp and koi × goldfish hybrids to koi herpesvirus (KHV) and the development of KHV disease (KHVD)

Hybrids of koi, Cyprinus carpio × crucian carp, Carassius carassius and koi × goldfish, Carassius auratus, proved to be susceptible to koi herpesvirus (KHV, syn. CyHV‐3) and developed KHV disease (KHVD). While hybrids of koi × goldfish were partly resistant to mortality following infection by immersion, most koi × crucian carp hybrids died after bath infection. KHV DNA was detected in dead fish but also in all surviving animals by different polymerase chain reactions (PCRs). According to these results, hybrid crossbreeding does not seem to prevent severe losses associated with KHV in terms of inducing KHVD. The present study showed severe losses after a waterborne KHV infection of between 35% and 100% in koi × goldfish and koi × crucian carp hybrids as well as in SPF carp.     

Proliferative kidney disease and renal myxosporidiosis in juvenile salmonids from rivers in England and Wales

The results from a survey for proliferative kidney disease (PKD) and renal myxosporidiosis in wild salmonids from rivers in England and Wales are presented. One hundred and eighty-five salmon, Salmo salar , 235 brown trout, Salmo trutta , 16 charr, Salvelinus alpinus, and five grayling, Thymallus thymallus, were obtained from 23 locations on 16 rivers between July and October 1997. They were examined for the presence of clinical PKD and for histological evidence of infections with Tetracapsula bryosalmonae and other renal myxozoans. Prevalence of infection with T. bryosalmonae detected histologically in brown trout varied from 11 to 43% in enzootic rivers and was only found in salmon in two rivers at low prevalence. Nephromegaly was positively associated with PKD in brown trout but in salmon mild nephromegaly was only associated with infection with an unidentified Chloromyxum sp.     

黑龙江地区鲤疱疹病毒3型的流行病学调查及其主要囊膜蛋白的抗原表位预测

2015-2016年对来自黑龙江地区46个养殖场送检的鲤鱼进行锦鲤疱疹病毒(Koi herpes virus,KHV)的分离鉴定,并应用DNAStar等软件对检出的阳性样本的主要囊膜蛋白(Major envelop protein,MEP)基因进行生物信息学分析。结果显示,KHV的检出率约为6.5%,3株阳性样本具有相同的MEP基因序列,称之为KHV-HLJ1516。MEP基因开放阅读框为771 bp,编码256个氨基酸,相对分子质量为28 280.58,等电点为8.40。对KHV-HLJ1516的MEP基因序列同源性分析表明,其与KHV-GZ11分离株仅有1个碱基不同,但并未导致氨基酸发生改变,碱基相似性为99%;而与HZ419分离株相比,KHV-HLJ1516的MEP基因有3个碱基发生突变,相应的氨基酸由Asn变为IIe。聚类分析结果显示,KHV-HLJ1516与KHV-GZ11处于同一分支,而HZ419位于另一分支。B细胞抗原表位预测结果显示,KHV-HLJ1516的MEP的抗原表位主要位于4~11,24~40,42~63,82~110,209~218,238~249氨基酸区段。     

Economic evaluation of inland fisheries in England and Wales

Recreational inland fisheries are recognized to have considerable socio-economic benefits, not only for individuals participating directly but also for others in both local and wider communities. In England and Wales the Environment Agency (EA) has a duty to maintain, improve and develop inland fisheries. At present, there are no recent economic evaluations of the whole range of UK inland fisheries for the EA to refer to when confronted with resource issues. There is a particular need to explore the benefits of fisheries to the wider community, in order to secure more resources for management and protection of fisheries. Preliminary results from a multi-modular project to study the economic values associated with recreational fisheries in England and Wales are presented. Topics examined included recreational anglers' consumer surplus, general public non-use values of fisheries, social benefits of recreational fishing and impacts of fisheries on local communities.     

Examining changes in participation in recreational fisheries in England and Wales

Abstract Inland fisheries in England and Wales have high economic and social values. Managing participation to maximise fishery performance is key to maintaining this status. The capital value of fishing rights for migratory salmonid fisheries is €165 million. Coarse fisheries contribute €1030 million to the economy. The central tenet to increasing participation in recreational salmonid fisheries is that an increase in stock size will result in more anglers accessing the fishery. This was examined for salmon on the rivers Usk and Lune where exploitation restrictions increased the number of salmon available to anglers. On the River Lune, the number of salmon available post‐intervention increased by 66%. There was no significant increase in catch while the number of anglers decreased by 16.3%. On the River Usk, the closure of the net fishery potentially resulted in an additional ～1200 salmon being available. Following closure, there was no significant change in rod catch or in the number of anglers. Increased participation is dependent less upon stock manipulation for coarse fisheries and more upon facilitating the activity. In recent years, urban fishery development programmes have provided improved access to local fishing opportunity. Also, new anglers have been targeted through campaigns such as Get Hooked on Fishing and the Scout Angler Badge.     

Aspects of fisheries and water resources management in England and Wales

Freshwater fish populations in England and Wales form an important resource with up to 2.2 million anglers involved in the recreational fishery. The resource consists principally of indigenous and naturalised cyprinids, and strongholds of species endangered elsewhere in Europe. Each component is under pressure from a range of sources including water abstraction and climate change. Water resources are under significant pressure and droughts in parts of England and Wales exposed the fragility of water supply systems. Climate change is a major concern, driving a re-assessment of water supply yields. There are no objective methods available to predict changes in fish communities likely to arise from different water resource management options, except for simple systems. It is difficult to manage water resources using anything other than a precautionary approach. Accurate assessment of environmental requirements are required to strike the right balance between the needs of aquatic ecosystems and of economic efficiency.     

Isolation and characterization of koi herpesvirus (KHV) from Indonesia: identification of a new genetic lineage

Koi herpesvirus (KHV) is the aetiological agent of an emerging disease (KHVD) associated with mass mortalities in koi and common carp and reported from at least 30 countries. We report the first isolation of KHV from koi and common carp in Indonesia and initial characterization of the isolates. Clinical signs, histopathology and virion morphology are similar to those of isolates from other countries. Phylogenetic analyses using the thymidine kinase gene amplified from each isolate and from carp tissue samples collected from KHVD outbreaks throughout Indonesia indicated that the Indonesian isolates are more closely related to the Asian than the European KHV lineage. Sequence analysis of two other variable regions between ORF29 and ORF31 (marker I) and near the start of ORF 133 (marker II) indicated that all Indonesian isolates displayed a marker I allele (I(++)) previously identified only in isolates of the Asian lineage. However, in the marker II region, all Indonesian isolates displayed the II(-) allele, which has been reported previously only amongst isolates of the European lineage, and nine of these displayed a mixed genotype (II(+)II(-)). The I(++)II(-) genotype has not been reported previously and appears to represent a new intermediate lineage that may have emerged in Indonesia.     

Social control of growth in Macrobrachium rosenbergii (De Man): a review and prospects for future research

The wide range of sizes of sexually mature prawn populations and particularly of the males is very typical of Macrobrachium rosenbergii (De Man) and a major obstacle to increased profitability of prawn culture. Prawn size variation reflects a complex population structure composed of three major male morphotypes – the small males, the orange‐claw males and the blue‐claw males – which differ in their morphology, physiology and behaviour. Social interactions among juveniles and among sexually mature males affect their growth. Four different social mechanisms have been suggested to control growth in crustaceans: direct competition for food, appetite suppression, altered food‐conversion efficiency and increased energy expenditure on motor activity. Since all growth‐controlling mechanisms involve an aggressive behavioural component, our knowledge of prawn agonistic behaviour and prawn social organization has been reviewed. Present knowledge of the social mechanisms regulating growth among juveniles and among sexually mature male morphotypes as well as the sensory modalities involved was evaluated. The possible evolution of social growth‐controlling mechanisms is discussed. Various ways for implementing our knowledge on social control of growth into prawn culture to increase profitability are suggested.     

Variation in the population density of adult sea-trout, Salmo trutta, in 67 rivers in England and Wales

Abstract– Analysis of annual rod and commercial catches of adult seatrout demonstrated strong positive relationships between large-scale spatial variance (S²_s, variation in catches between rivers for each year) and spatial mean density (x?_s, mean catch per year), and also between temporal variance (S²_t, variation in catches between years for each river) and temporal mean density (x?_t, mean catch for each river). Both relationships were described by a power function, s²=ax^-b. For spatial variability, there were no significant differences between power functions for both rod and commercial catches from the North West, Welsh and South West regions. As the power b was not significantly different from two, relative spatial variability (measured by coefficients of variation (CV)) was fairly constant between years. Significantly higher values of b were obtained for the Wessex (GM b= 2.233) and North East (GM b=2.824) regions, and therefore the increase in CV with mean annual catch was significant but slight for Wessex rivers and marked for North East rivers. For temporal variability, there were no significant differences between power functions for both rod and commercial catches from all 5 regions and therefore a common power function was fitted to the data from all 67 rivers. As the power b was significantly less than two (GM b= 1.729), relative temporal variability (measured by CV) decreased significantly with increasing mean catch per river. Some limitations and implications of this analysis are discussed. Similar results from different regions for both rod and commercial catches suggest that such data do reflect adult population density, in spite of the different methods used to catch the sea-trout, variations in fishing effort and failures to report catches. The analysis of temporal variability provides a basis for classifying the major sea-trout rivers according to their mean annual catch and their relative variability in catches between years (using the CV).     

拟态弧菌感染黄颡鱼的动态病理损伤及病原分布研究

以1.0×106CFU·m L~(-1)拟态弧菌(Vibrio mimicus)浸浴感染黄颡鱼(Pelteobagrus fulvidraco),于第0、第4、第8、第16、第24、第36、第48、第60、第72小时剖杀取样,研究病理损伤及病原菌的体内动态分布。结果显示,皮肤肌肉、鳃、肠道出现病变最早,其中皮肤肌肉损伤最严重。第16小时表皮变性、坏死,鳃上皮肿胀,肠绒毛水肿;第24~第48小时表皮坏死、脱落,真皮严重出血,肌纤维变性、坏死,鳃出血,上皮局部坏死,肠上皮变性与灶性坏死;第48~第72小时皮肤肌肉坏死更严重,形成溃疡灶,鳃灶性坏死。肾、肝、脾与心36 h后相继出现不同程度的淤血、出血,变性和灶性坏死。q PCR检测发现,第4小时即在鳃、肠、皮肤肌肉检出病菌,细菌含量分别为1.3×102CFU·mg~(-1)、2.6×102CFU·mg~(-1)、4.7×102CFU·mg~(-1);鳃与皮肤肌肉中菌量随时间延长而增加,第72小时皮肤肌肉中菌量达到4.5×107CFU·mg~(-1);第24小时后相继在肾、肝、脾、心检出病菌,菌量介于1.9×10~4.7×102CFU·mg~(-1)之间。结果表明皮肤、鳃和肠道是病菌的入侵位点,并在体内多组织、器官分布。