Welfare of fish

Η ευζωία των ψαριών και γενικότερα όλων των ζώων είναι μια έννοια που δηλώνει μια ανώδυνη και μη οτρεσογόνα κατάσταση διαβίωσης. Τέτοια έννοια, αν και τα προηγούμενα χρόνια είχε πολλές φορές αμφισβητηθεί από τους παράγωγους, θεσμοθετείται πλέον αυστηρά από πολλές χώρες. Για τα ψάρια, λίγα είναι τα παραδείγματα τέτοιας θεσμοθέτησης, όπως, για παράδειγμα, στη Νορβηγία και στη Γερμανία η θανάτωση για ανθρώπινη κατανάλωση πρέπει να πραγματοποιείται βασιζόμενη σε συγκεκριμένες τεχνικές, συμβατές με την ευζωία των ψαριών. Όλα τα ζώα χρειάζονται μια σταθερότητα του περιβάλλοντος διαβίωσης προκειμένου να επιβιώσουν, να αναπτυχθούν και να αναπαραχθούν .Η μη εξασφάλιση τέτοιας σταθερότητας ορίζεται ως κατάσταση στρες. Στα ψάρια, οι αιτίες που μπορούν να τους προκαλέσουν στρες είναι ποικίλες. Πρώτον, σχεδόν όλοι οι χειρισμοί που πραγματοποιούνται σε επίπεδο ιχθυοκαλλιέργειας θεωρούνται στρεσογόνοι (π.χ. μεταφορά). Δεύτερον, οι ακατάλληλες συνθήκες εκτροφής, π.χ. η υψηλή ιχθυοπυκνότητα και ένα μη ισορροπημένο σιτηρέσιο, θέτουν σε αμφισβήτηση την ευζωία των ψαριών. Στοίδιο αποτέλεσμα οδηγούν και άλλοι παράγοντες, όπως η ακατάλληλη ποιότητα του νερού εκτροφής, οι τεχνικές που χρησιμοποιούνται για την πρόληψη και θεραπεία ασθενειών, οι τεχνικές θανάτωσης και η μεταφορά.Fish welfare and in general the welfare of animals is a term that declares a painless and not stressfull state of being. During the previous years this term has been questioned by the producers, however, nowadays, it is actually legally regulated in several countries. For fishes, few are the examples of such enforcement, such as in Norway and Germany where the killing of fish for human consumption bases on techniques compatible with their welfare. All the animals need a stable environment of being so that they can survive, develop and reproduce. The absence of such a stability is termed as stress. There are various causes of producing stress in fish. Firsdy, almost all management procedures that are practiced commercially result in stress (e.g. transport). Secondly, inadequate conditions of farming, such as the high stocking-density and an unbalanced food, place the welfare of fishes at risk. To the same result may also lead other factors, such as the unsuitable quality of the rearing water, the techniques that are used for the prevention and treatment of illnesses, the techniques of killing and also transport

16S-23S rRNA Internal Transcribed Spacer Region (ITS) Sequencing: A Potential Molecular Diagnostic Tool for Differentiating Lactococcus garvieae and Lactococcus petauri

Lactococcus garvieae is the etiological agent of lactococcosis, a clinically and economically significant infectious disease affecting farmed rainbow trout. L. garvieae had been considered the only cause of lactococcosis for a long time; however, L. petauri, another species of the genus Lactococcus, has lately been linked to the same disease. The genomes and biochemical profiles of L. petauri and L. garvieae have a high degree of similarity. Traditional diagnostic tests currently available cannot distinguish between these two species. The aim of this study was to use the transcribed spacer (ITS) region between 16S rRNA and 23S rRNA as a potential useful molecular target to differentiate L. garvieae from L. petauri, saving time and money compared to genomics methods currently used as diagnostic tools for accurate discrimination between these two species. The ITS region of 82 strains was amplified and sequenced. The amplified fragments varied in size from 500 to 550 bp. Based on the sequence, seven SNPs were identified that separate L. garvieae from L. petauri. The 16S-23S rRNA ITS region has enough resolution to distinguish between closely related L. garvieae and L. petauri and it can be used as a diagnostic marker to quickly identify the pathogens in a lactococcosis outbreak

Antibacterial drugs in products originating from aquaculture: assessing the risks to public welfare

As aquaculture expands to meet human demand and compensate for pessimistic forecasts of fisheries catches, use of antibacterial agents to combat or forestall bacterial diseases is still a necessity, although effective vaccines and improved hygiene have aided drastically in this battle. The hazards for the consumer perspective arising from the imprudent use of such chemicals can be detrimental, especially if the residues persist above legal tolerance. These may include selection and dissemination of resistant bacteria, disruption of the colonization barrier in the human intestinal flora and allergic reactions. In cases that unlawful drugs reached the consumer via consumption of aquatic products, human health may be jeopardized even further. The present review article assesses these risks to human health

Prevalence of Listeria spp. in freshwater fish(Oncorhynchus mykiss and Carassius gibelio) and the environment of fish markets in Northern Greece

In this study, a total of 405 samples from freshwater fish, personnel and environment were collected from retail fish markets in three cities in Northern Greece and they were examined for the presence of Listeria spp. They consisted of 136 samples from the skin and 136 from the flesh of 71 rainbow trout (Oncorhynchus mykiss) and 65 gibel carps (Carassius gibelio), 20 from workers' hands, 27 from workers' knives, 22 from working surfaces, 29 from wooden boxes, 15 from plastic boxes, 18 from floor surfaces and 2 from drainage lids. Listeria spp. was isolated from 10.62% of the samples, L. rnonocytogenes were 0.99%, 4.69% L. seeligeri and 4.94% L. innocua, respectively. L. monocytogenes was isolated from 3.54% of the environmental samples and none from fresh water fish and workers hands' samples. Listeria spp. was isolated from 1.54% of gibel carp flesh (1.54% L. seeligeri), from 18.46% of gibel carp skin (10.77% L. seeligeri and 7.69% L. innocua) and from 8.45% from rainbow trout skin samples (1.41% L. seeligeri and 7.04% L. innocua). The higher rate of isolation of Listeria spp. from the environmental samples emphasises the importance of sanitary conditions in order to reduce the risk of contamination by L. monocytogenes at the retail level

Prevalence ofListeria spp. in freshwater fish (Oncorhynchus my kiss and Carassius gibelio) and the environment offish markets in Northern Greece [Παρουσία των Listeria spp. σε ψάρια του γλυκού νεροΰ (Oncorhynchus mykìss και Carassius gibelio) και στο περιβάλλον ιχθυοπωλείων της Βόρειας Ελλάδας]

In this study, a total of 405 samples from freshwater fish, personnel and environment were collected from retail fish markets in three cities in Northern Greece and they were examined for the presence of Listeria spp. They consisted of 136 samples from the skin and 136 from the flesh of 71 rainbow trout (Oncorhynchus mykiss) and 65 gibel carps (Carassius gibelio), 20 from workers' hands, 27 from workers' knives, 22 from working surfaces, 29 from wooden boxes, 15 from plastic boxes, 18 from floor surfaces and 2 from drainage lids. Listeria spp. was isolated from 10.62% of the samples, L. monocytogenes were 0.99%, 4.69% L. seeligeri and 4.94% L. innocua, respectively. L. monocytogenes was isolated from 3.54% of the environmental samples and none from fresh water fish and workers hands' samples. Listeria spp. was isolated from 1.54% of gibel carp flesh (1.54% L. seeligeri), from 18.46% of gibel carp skin (10.77% L. seeligeri and 7.69% L. innocua) and from 8.45% from rainbow trout skin samples (1.41% L. seeligeri and 7.04% L. innocua). The higher rate of isolation of Listeria spp. from the environmental samples emphasises the importance of sanitary conditions in order to reduce the risk of contamination by L. monocytogenes at the retail level © 2017. Journal of the Hellenic Veterinary Medical Society.All Rights Reserve

Occurrence and molecular characterization of betanodaviruses in fish and invertebrates of the Greek territorial waters

Betanodaviruses are small ssRNA viruses that cause viral encephalopathy and retinopathy, a severe neuropathological infectious disease in marine fish species worldwide. In the present study, the occurrence of betanodaviruses was investigated in wild and cultured populations of fishes and invertebrates of the Greek territorial waters. Betanodaviruses were detected in 35 species belonging to 21 families and 12 orders. To our knowledge, 23 of those are reported for the first time in Greek waters, while 11 of them are reported for the first time globally. The positive samples were subjected to sequencing and phylogenetic analysis of partial segments of RNA1 and RNA2 genes. Almost all the viruses circulating in Greece fell within RGNNV genotype, while reassortant viruses were detected in three samples, namely two inter-RGNNV and one RGNNV/SJNNV. A novel unclassified Betanodavirus sequence was also identified. Most of the Greek sequence types have a restricted geographic distribution except for two RNA1 and one RNA2 sequence types that are widespread throughout the Mediterranean basin. The results of this study indicate the range of reservoirs/hosts of betanodaviruses and also their wide spread in the Greek territorial waters and reinforce the hypothesis that wild fish species transmit the virus to cultured ones and vice versa. © 2019 John Wiley & Sons Lt