Trout

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Disease outbreaks negatively affect fish production. Antimicrobial agents used in the treatment of diseases become ineffective over time because of antibiotic resistance developed by bacteria distributed in the aquaculture environment. This study was conducted for 4 months (cold period) in a fish farm to detect the fish disease, cold water streptococcosis. In the study, four brood stock showing disease signs were detected. Bacteria isolates were obtained and identified as Vagococcus salmoninarum . Antimicrobial susceptibility of V...

Since the first introduction from North America more than a century ago, rainbow trout (Oncorhynchus mykiss) have rapidly established self-sustaining populations in major river basins of Patagonia. Many generations later, only the freshwater resident life history is expressed in the Chubut and Negro rivers of northern Argentinian Patagonia, whereas both the resident and anadromous life histories are found in the Santa Cruz River of southern Argentina. Despite previous studies that have tried to identify the sources of these introduced populations, uncertainty still exists...

The study investigated if gonad maturation in triploid brown trout, Salmo trutta, was entirely suppressed or only delayed, and if triploids could interbreed with diploid counterparts. Ten percent of the total number of 3-year-old triploid S. trutta, 15% of 4-year-old fish, and 17% of 5-year-old fish produced semen. Three and 4 years old triploid fish did not produce eggs, but 15% of the 5-year-old fish did so. The quantity and sperm motility of triploid semen did not differ from diploids, but the sperm concentration was significantly lower...

Parasitic sea lice (Copepoda: Caligidae) colonising marine salmonid (Salmoniformes: Salmonidae) aquaculture production facilities have been implicated as a possible pressure on wild salmon and sea trout populations. This investigation uses monitoring data from the mainland west coast and Western Isles of Scotland to estimate the association of the abundance of adult female Lepeophtheirus salmonis (Krøyer) colonising farmed Atlantic salmon Salmo salar L. with the occurrence of juvenile and mobile L. salmonis on wild sea trout, anadromous S...

Aeromonas salmonicida is an important pathogen that causes furunculosis in trout and salmon with high morbidity and mortality, resulting in significant economic losses in aquaculture. Overuse of antibiotics has led to the continuous emergence of drug-resistant strains. Hence, there is an urgent need to find an alternative environmentally friendly antimicrobial agent. In this study, we isolated a virulent phage of A. salmonicida , named ASG01, which belongs to the Myoviridae family and maintains lytic activity at a pH value range from 4 to 12 and in the temperature range from 30 °C to 60 °C...

Chemokines are cytokines with chemoattractant capacities that exert their physiological functions through the binding of chemokine receptors. Thus, chemokine and receptor complexes exert important roles in regulating development and homeostasis during routine immune surveillance and inflammation. Compared to mammals, the physiology and structure of chemokine receptors in fish have not been systematically studied. Furthermore, the salmonid-specific whole genome duplication has significantly increased the number of functional paralogs of chemokine receptors...

Seven-month-old rainbow trout acclimated to 9 °C were used. The fish were gradually adapted to a water temperature of 20 °C over a period of seven days and then exposed to this temperature for 32 days. Changes in gill morphometry and histology and in enzyme activities in comparison to fish kept at 9 °C were investigated. No histopathological abnormalities were discerned at the heightened temperature. The gill epithelium thickened by approximately 40%, suggesting an increase in the branchial diffusion barrier for ions, water, and gases...

Recent studies have demonstrated that immune-related recombinant proteins can enhance immune function, increasing host survival against infectious diseases in salmonids. This research evaluated inclusion bodies (IBs) of antimicrobial peptides (CAMPIB and HAMPIB ) and a cytokine (IL1βIB and TNFαIB ) as potential immunostimulants in farmed salmonids. For this purpose, we produced five IBs (including iRFPIB as a control), and we evaluated their ability to modulate immune marker gene expression of three IBs in the RTS11 cell line by RT-qPCR...

The impacts of hypolipidemic pharmaceuticals on fish lipid metabolism remain unexplored. However, data points to similar effects and mechanisms of action between fish and humans. Therefore, fish may be a strong model for screening hypolipidemic drug candidates and water pollution by lipid-modulating agents. This study aimed to test a new hypolipidemic model assay with juvenile brown trout using atorvastatin (ATV)-a hypolipidemic chemical. We selected 17α-ethinylestradiol (EE2), known to cause hyperlipidemia in fish, to ensure model functionality...

Every year, ulcerative dermal necrosis (UDN) affects salmonids that spend most of their lives in the sea during their migration to the rivers of northern Poland to spawn. The clinical form of the disease manifests itself in ulcerative skin lesions, which lead to significant weakening of the fish and, in most cases, result in their death. This study was carried out on samples taken from sea trout in the Słupia River in northern Poland. In order to identify the pathogen, experiments on the transmission of the disease were carried out, and additional histopathological, microbiological and electron microscopic examinations were performed...

A requisite to improving the taste and odor attributes of farmed fish is the availability of accurate and practical analytical methods to quantify 2-methylisoborneol (MIB) and geosmin (GSM). Solid-phase microextraction (SPME) enables reliable measurement of nanogram per liter quantities of MIB and GSM in water. In contrast, direct headspace (HS)-SPME of biological matrices with variable proximate compositions can increase bias and uncertainty in off-flavor determinations. Analytical recovery plays a crucial role in the accurate determination of MIB and GSM in fish, and this study investigates strategies to maximize and account for this recovery factor...

Recent studies have reported on the importance of RBCs in fish responses to viral infections and DNA vaccines. Surface-displaying recombinant bacterins (spinycterins) are a safe and adaptable prototype for viral vaccination of fish and represent an alternative method of aquaculture prophylaxis, since have been reported to enhance fish immune response. We evaluated the innate immune response of rainbow trout ( Oncorhynchus mykiss ) red blood cells (RBCs), head kidney, and spleen to spinycterins expressing a fragment of the glycoprotein G of viral haemorrhagic septicemia virus (VHSV), one of the most devastating world-wide diseases in farmed salmonids...

OBJECTIVE: Doxycycline (DO) has been used in fish for a long time, but there are some factors that have not yet been clarified regarding its pharmacokinetic (PK) and pharmacodynamic (PD) properties. Therefore, the aim of this study was to investigate the PK and PK/PD targets of DO after 20 mg/kg intravascular (IV), intramuscular (IM) and oral (OR) gavage administration in rainbow trout (Oncorhynchus mykiss). METHODS: Plasma samples were collected at specific time points and subsequently analysed by HPLC-ultraviolet...

Flavobacterium columnare causes columnaris disease in fish. Columnaris disease is incompletely understood, and adequate control measures are lacking. The type IX secretion system (T9SS) is required for F. columnare gliding motility and virulence. The T9SS and gliding motility machineries share some, but not all, components. GldN (required for gliding and for secretion) and PorV (involved in secretion but not required for gliding) are both needed for virulence, implicating T9SS-mediated secretion in virulence...

Genetic monitoring of Pacific salmon in the Columbia River basin provides crucial information to fisheries managers that is otherwise challenging to obtain using traditional methods. Monitoring programs such as genetic stock identification (GSI) and parentage-based tagging (PBT) involve genotyping tens of thousands of individuals annually. Although rare, these large sample collections inevitably include misidentified species, which exhibit low genotyping success on species-specific Genotyping-in-Thousands by sequencing (GT-seq) panels...

Metagenomic sequencing has proven to be a powerful tool in the monitoring of antimicrobial resistance (AMR). Here, we provide a comparative analysis of the resistome from pigs, poultry, veal calves, turkey, and rainbow trout, for a total of 538 herds across nine European countries. We calculated the effects of per-farm management practices and antimicrobial usage (AMU) on the resistome in pigs, broilers, and veal calves. We also provide an in-depth study of the associations between bacterial diversity, resistome diversity, and AMR abundances as well as co-occurrence analysis of bacterial taxa and antimicrobial resistance genes (ARGs) and the universality of the latter...

In summer, the survival zones of cold-water species are predicted to narrow by both increasing water temperatures from the surface and by expanding hypoxic zones from the lake bottom. To examine how the abundance of cold-water fishes changes along environmental gradients, we assessed the vertical environmental DNA (eDNA) distributions of three salmonid species which may have different water temperature tolerances during both stratification and turnover periods using quantitative PCR (qPCR). In addition, we examined on the vertical distribution of diverse fish fauna using an eDNA metabarcoding assay...

Aquatic ecosystems continue to be threatened by chemical pollution. To what extent organisms are able to cope with chemical exposure depends on their ability to display mechanisms of defense across different organs. Among these mechanisms, biotransformation processes represent key physiological responses that facilitate detoxification and reduce the bioaccumulation potential of chemicals. Biotransformation does not only depend on the ability of different organs to display biotransformation enzymes but also on the affinity of chemicals towards these enzymes...

Acoustic tags fitted with predation sensors, which trigger following ingestion by piscivorous predators, were used to compare direct predation rates during downstream migration (out-migration) of potamodromous (freshwater) brown trout (Salmo trutta L.) parr from their natal river into a large freshwater lake system during spring and autumn. Thirty-eight spring migrants were tagged across two study years (2021 and 2022) of which 13 individuals (34%) were predated. By contrast 40 autumn migrants were tagged (2020 and 2021) of which three individuals (7...