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The Community Action Plan requests EU member states to implement measures that ensure the recovery of the severely depleted European eel stocks. One of the main threats is posed by Anguillid herpesvirus 1 (AngHV-1) leading to increased mortality in both wild and farmed eels. Following recommendations of the OIE to minimize the risk of obtaining false-negative results, the main aim of the study was to optimize diagnostic methods for AngHV-1 detection using conventional PCR, nested PCR and in situ hybridization assay. While 53.3% of the individual organ samples were tested positive for AngHV-1 by PCR, the additional virus analysis via nested PCR revealed that the actual prevalence was 93.3%. In the cell cultivation passages, a cytopathic effect was hardly found in the first two rounds. In the third passage onto cell cultures, a lytic CPE was detected. The identification and confirmation of the viruses obtained from cell cultures as well as directly from the organ tissues were proceeded by PCR, nested PCR and sequencing of the PCR products. While no positive signal was detectable in the first round by PCR using samples from the third cell culture passages, the nested PCR provided weak but visible positive signals., (© 2017 John Wiley & Sons Ltd.)

Climate change will expose the food‐producing sector to a range of challenges. Inland aquaculture farms are particularly vulnerable, due to the difficulty in changing their location, and therefore require specific tools to predict the influence of direct and indirect effects on production, environment and economic feasibility. The objective of our study was to apply a simple set of models to produce a set of growth, risk and suitability maps for stakeholders within the common carp sector in Poland, to assist decision‐making under two different scenarios of climate change: a moderate situation (RCP 4.5) and an extreme situation (RCP 8.5). We used present (2000–2019) and future projections (2080–2099) for water surface temperature based on land surface temperature data from regionally downscaled climate models to draw maps to: (i) show optimal temperature conditions for carp growth, (ii) assess risk of disease outbreak caused by three important common carp pathogens: Cyprinid herpesvirus 3 (CyHV‐3), carp oedema virus (CEV) and spring viremia of carp (SVCV) and (iii) predict potential suitability changes of carp farming in Poland. The study identified areas with the most and least favourable temperature conditions for carp growth, as well as those areas with the highest/lowest number of days with suitable temperatures for virus infection. These suitability maps showed the combined effect of direct and indirect effects of climate change projections under RCP 8.5 and RCP 4.5 scenarios. The approach applied herein will be of use worldwide for analysing the risks of temperature increase to land‐based aquaculture, and the results presented are important for carp farmers in Poland and elsewhere, industry in general, and government stakeholders, to understand the direct and indirect effects of climate change on the triple bottom line of people, planet, and profit. [ABSTRACT FROM AUTHOR]

Background. White sturgeon iridovirus (WSIV) is one of the most serious threats for sturgeon aquaculture as the mortality in juvenile individuals can reach 95%. At the turn of the century WSIV was reported among hatcheryraised white sturgeon, Acipenser transmontanus Richardson, 1836, in North America, Russian sturgeon, Acipenser gueldenstaedtii Brandt et Ratzeburg, 1833, in northern Europe but also pallid sturgeon, Scaphirhynchus albus (Forbes et Richardson, 1905) and shovelnose sturgeon, Scaphirhynchus platorynchus (Rafinesque, 1820) in North and South Dakota. The clinical signs of infection include cessation of feeding and edematous and pale gills. Those pathological changes lead to respiratory problems of the juveniles and deterioration of their overall condition. Rapid detection of pathogen particles under aquaculture conditions is crucial, therefore the principal aim of this study was to establish a molecular method for rapid and effective detection of the WSIV. This is the first study thoroughly comparing WSIV detection methods in sturgeons cultured in Poland, Germany, and Italy. Material and methods. A total of 244 samples were collected from 82 sturgeons representing six species: beluga, Huso huso (Linnaeus, 1758); sterlet, Acipenser ruthenus Linnaeus, 1758; Siberian sturgeon, Acipenser baerii Brandt, 1869; Russian sturgeon, A. gueldenstaedtii; Atlantic sturgeon, Acipenser oxyrinchus Mitchill, 1815; and European sea sturgeon, Acipenser sturio Linnaeus, 1758, as well as five sturgeon hybrids: Siberian × Russian, Adriatic (Acipenser naccarii Bonaparte, 1836) × Siberian, Adriatic × beluga, Siberian × sterlet, and beluga × sterlet. The samples were screened for the WSIV using conventional PCR, real-time PCR, and in situ hybridization (ISH) methods. Results. In total, positive results were obtained in 231 (94.67%) out of 244 analysed samples, except for H. huso where DNA of WSIV was not identified. DNA of WSIV was most frequently detected in the kidney (97.92%), intestine (97.50%), skin (94.97%), and gills (93.29%). The most effective method for detecting DNA of WSIV in sturgeons was real-time PCR (92.62% of), PCR (90.98%), and ISH (49.24%). Conclusion. The host range of the WSIV seems to be wider than expected, however, further studies are necessary since no clinical symptoms were observed in sturgeons and their hybrids. [ABSTRACT FROM AUTHOR]

Tench, Tinca tinca is a freshwater species which receives increasing attention as marine resources are overexploited and alternative feed components must be implemented to enable sustainable development of aquaculture. The aim of the study was to provide scientists and fish farmers with first high quality annotated tench transcriptome and open a new chapter in tench research, especially when practical diets are tested. Therefore, the second aim was to identify differentially expressed contigs (DECs) in tench gut after 86-day trial where adult tench females were fed with 0% and 100% replacement of fish meal (FM) with poultry by-product meal (PBM). De novo assembling using de novo RNA-Seq Assembly Pipeline (DRAP) produced 64070 contigs where these exceeding 1 kbp were mostly annotated. Microsatellite search identified 23668 SSRs and SNPs were distributed in 118002 transitions and 83577 transversions. High quality of the assembly and annotation completeness of the tench transcriptome was confirmed using BUSCO and by mapping contigs against common carp, Cyprinus carpio and zebrafish, Danio rerio data sets. Analysis of gene expression differences between gut samples tench fed with FM and PBM diets revealed 721 and 69 DECs using edgeR and DESeq2, respectively. Venn diagram for these results filtered out 57 DECs which were common for both analysis. Due to a low number of annotated DECs enrichment analysis provided a low number of useful contigs for pathway or functional analysis. Nevertheless, each contig in the set was analysed through BLASTn and BLASTx and eighteen DECs were characterised and identified as mainly involved in response to different immune stimuli and disease states (e.g. cluster of differentiation 48 , F-type lectin ), cell adhesion (e.g. paracingulin ), digestion (e.g. serine proteases) and signal transduction (e.g. neurexophilin 3 , complexin 2 ). Moreover, study has shown that most of the identified in our study DECs (70.2%) were down regulated in gut samples of tench fed with PBM comparing to these with FM-based feed. This observation might indicate on disorganization of inter-epithelial junctions in ongoing inflammation process. Our de novo tench gut transcriptome assembly (online NGS Pipeline) provide a guide for further diverse studies because, understanding feed-gut interactions and intestinal homeostasis in farmed tench is important to maximise performance of this species and to ensure that freshwater aquaculture continues to be a sustainable source of food for a growing world population. [ABSTRACT FROM AUTHOR]