Author: marina02

FROZEN OUT: CAN MACROBRACHIUM ROSENBERGII SURVIVE FRENCH WINTERS ?

Introduction:

The freshwater prawn Macrobrachium rosenbergii is naturally distributed across South Asia and the Pacific, from eastern Papua New Guinea to western Pakistan. This species is commercially valuable and widely farmed in tropical regions due to its high growth rate and tolerance to warm temperatures. Optimal growth and survival are observed between 28°C and 32°C. However, its sensitivity to cold temperatures and the need for brackish water to complete its reproductive cycle limit its cultivation in temperate zones to short periods during the year.

In the United States, M. rosenbergii farming is practiced with hatchery-based larval production in winter and spring, followed by on-growing in outdoor ponds during summer. Based on the same principle, the rearing of M. rosenbergii has aroused growing interest in France. In addition, given the forecast rise in temperatures due to global change, the rearing season could be extended and productivity improved. However, concerns have been raised about the potential invasive risk if the species is accidentally released into the wild.

Methods and Results:

This study aimed to simulate seasonal temperature decline and assess M. rosenbergii’s cold tolerance through chronic cold stress. Triplicate groups of prawns were exposed to a progressive temperature decrease of 1°C every 3.5 days until 100% mortality was reached. While control prawns remained alive throughout the experiment, mortality in cold-treated groups began between 17–16°C, with complete mortality occurring three days after reaching 13°C. Despite cessation of feeding below 20°C, no weight loss was observed, indicating that death was not due to malnutrition. Both control and treated prawns exhibited frequent molting, suggesting that overall rearing conditions were adequate. Interestingly, two cold-exposed prawns molted less than 24 hours before dying at 16°C. Additionally, while control prawns exhibited a dark blue coloration adapted to their dark background, cold-stressed individuals developed a yellowish shell, suggesting impaired background adaptation and increased vulnerability to predation.

Conclusion:

Overall, these results indicate that even if slowly acclimated to temperature drop, M. rosenbergii remains highly sensitive to cold. This suggests that in case of direct exposure to cold water with no shelter, M. rosenberbii is unlikely to survive winter conditions in France, where temperatures below 13°C are common.

1. OSTERHELD, KEVIN, Oniris, INRAE, BIOEPAR, 44300 Nantes, France, Presenter
2. PINEAU, LIONEL, Oniris, INRAE, BIOEPAR, 44300 Nantes, France, Author
3. CALVEZ, SEGOLENE, Oniris, INRAE, BIOEPAR, 44300 Nantes, France, Author

Tilapia welfare assessment in Thailand: Perspectives from the farm to the local markets

Tilapia (Oreochromis spp.) is an important aquatic species in Thailand’s aquaculture industry. However, welfare considerations throughout the production chain, from farming practices to slaughter methods in local markets, remain limited. This study evaluates tilapia welfare across different production stages, integrating on-farm assessments with an analysis of stunning techniques used during slaughter. Welfare indicators—including health, environment, behavior, and nutrition—were assessed at eight tilapia farms employing either earthen pond or cage culture systems across Thailand. While no significant differences in overall welfare scores were observed between systems, behavioral indicators were consistently low across all farms, highlighting poor handling practices during harvest that contributed to stress and potential welfare compromises. Additionally, six stunning methods—percussive stunning (wooden priest and bolt pistol), ikijime, live freezing, anesthesia, and asphyxiation—were evaluated for their effects on fish welfare and meat quality. Percussive stunning with a bolt pistol and anesthetic overdose effectively minimized stress responses and morphological damage, whereas stunning with a wooden priest and asphyxiation resulted in significant distress and lower meat quality. A survey of fifteen fishmongers from local markets revealed that stunning with a wooden priest, the knife handle, or asphyxiation remained the most commonly used slaughtering techniques, despite their poor welfare outcomes. This indicates limited awareness of humane slaughter practices and emphasizes the need for education and the adoption of welfare-friendly methods. These findings offer important insights for improving tilapia welfare at both the farm and market levels, elevating ethical aquaculture practices and enhancing the quality of fish products in Thailand.

1. LERTWANAKARN, TUCHAKORN, Department of Physiology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand, Presenter
2. SURACHETPONG, WIN, Department of Veterinary Microbiology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand, Author

Following the carp clause: Common carp (Cyprinus carpio) welfare status in the Czech Republic and Germany within the EU regulatory framework

Introduction: As aquaculture is the fastest-growing food sector worldwide, the topic of fish welfare is becoming more prominent. The increased attention aquatic animals have received highlighted substantial gaps in scientific and technical knowledge and in the legal protection of their welfare. To change this trend, many initiatives have emerged. Operating under the European Commission, the European Reference Centre for the Welfare of Aquatic Animals (EURCAW-Aqua) conducts species-specific research on welfare and aquaculture practices to support competent authorities in maintaining high welfare standards. Focusing on common carp (Cyprinus carpio), a species with the longest tradition of pond farming in central Europe, the aim of this study was to review welfare regulations in the Czech Republic and Germany within the context of EU legislation.

Methodology: The analysis was conducted through a comparative literature review. To identify relevant studies, academic databases and bibliographic resources, including Google Scholar, Scopus, and Science Direct, were searched using keywords such as common carp AND/OR welfare AND/OR regulations. Both countries’ primary and secondary animal welfare legislation as well as legally non-binding guidelines were assessed.

Results: Overall, the direct embedment of carp welfare protection is very limited inbothcountries and the species falls under general farmed animals’ regulations. In terms of hard law, theEU Regulation (EC) 1099/2009 and (EC) 1/2005 have been extended to farmed fish under the Czech and German legislation. Additionally, in Germany carp has been one of the two aquaculture species included in the national livestock welfare monitoring project. The sociocultural background through which the carp welfare is comprehended differs. As a typical Christmas meal, carp is taken into many Czech households still alive during the holidays, while in Germany, live fish are not sold to customers, reflecting the country’s stricter approach to animal welfare.

Conclusions: Effective animal welfare regulations depend on a species-specific approach, with no exception in aquaculture.Although extensive carp regulations in studied countries are lacking, new initiatives that could significantly improve the welfare status of carp arise. These may support it directly, such as the German National Animal Welfare Monitoring project or indirectly, e.g. the parliamentary proposal to include animal protection in the Czech Constitution.

Funding: Funded by the European Union under European Reference Centre for the Welfare of Aquatic Animals, Grant Agreement No. 101202280 (EURCAW-Aqua).

1. Křesalová, Tereza, Institute of Parasitology, Biology Centre Czech Academy of Sciences, České Budějovice, Czech Republic, Presenter
2. Holčáková, Anna, Institute of Parasitology, Biology Centre Czech Academy of Sciences, České Budějovice, Czech Republic, Author
3. Mladineo, Ivona, Institute of Parasitology, Biology Centre Czech Academy of Sciences, České Budějovice, Czech Republic, Author

unveiling the role of spirulina in the mitigation of sumithion-induced growth retardation, oxidative stress and immuno-toxicity in striped catfish (pangasianodon hypophthalmus)

sumithion is an organophosphate insecticide, widely used in aquaculture ponds to eradicate aquatic insect (mainly tiger bugs), typically applied before stocking fish larvae. however, it adversely affects non-target aquatic organisms, particularly fish. this study was conducted to evaluate the potential toxicity of sumithion in thai pangas (pangasianodon hypophthalmus) as well as the role of dietary spirulina (spirulina platensis) in mitigating the toxic effects of sumithion. over a 42-day trial, a total 240 of striped catfish fingerlings were exposed to four different treatments: control (without sumithion or spirulina), sumithion (0.6 mg/l), spirulina (50 g/kg feed) and combined treatment (sumithion + spirulina) with three replicates each. sumithion treated fish exhibited altered hemato-biochemical indices (haemoglobin and glucose) as well as erythrocyte morphology abnormalities—cellular (teardrop, twin, fusion) and nuclear (nuclear bridge, nuclear buds, notch, karyopyknosis); the intestinal structure was compromised, growth indices (wg, sgr %/day) were reduced, and fcr increased in sumithion treated fish. in contrast, spirulina—either alone or in combination with sumithion—significantly improved intestinal architecture, growth performance and feed efficiency. furthermore, sumithion exposure induced marked shifts in gene expression: antioxidant genes sod and cat were down regulated while gpx was up regulated, and immune related genes mhc ii and ifn β2 were up regulated whereas il 1β and ifn α2 were down regulated compared to control; spirulina supplementation reversed these trends, enhancing both immune and antioxidant gene responses. the current study thus demonstrates that dietary spirulina efficiently mitigates sumithion induced stress and promotes overall health in striped catfish by restoring hemato biochemical indices, intestinal integrity, growth performance and immune antioxidant gene expression.

1. BINTE ASHRAF, SAUDAH, LABORATORY OF FISH ECOPHYSIOLOGY,BANGLADESH AGRICULTURAL UNIVERSITY, Presenter
2. Amin, Md Ruhul, LABORATORY OF FISH ECOPHYSIOLOGY,BANGLADESH AGRICULTURAL UNIVERSITY, Author
3. Shahjahan, Md, LABORATORY OF FISH ECOPHYSIOLOGY,BANGLADESH AGRICULTURAL UNIVERSITY, Author

A Systematic Map of Vertebrate Intestinal Epithelial Cell Culture Techniques to Refine Salmonid Models

Introduction

Intestinal epithelial barrier cell models are utilised in numerous applications within fish health research including immunology, nutrition and toxicology. However, in other vertebrate species models, particularly those using human cell lines, more advanced methodologies such as scaffolds, matrices and co-cultures are often utilised. These techniques, though less well established in salmonid models, make the cell models more biologically representative of the intestine. This systematic map aimed to collate current and past approaches used in vertebrate barrier cell models to inform future work, refining and advancing intestinal cell culture models for salmonids.

Methodology

Systematic mapping was used to gather evidence from peer-reviewed journal articles, theses and dissertations in English, published from 1995–2025, where the cell model methodology was described. Searches were conducted across four databases: PubMed, Scopus, Web of Science and ProQuest Dissertations and Theses Global, using Boolean search strings. Duplicates were removed using EPPI-Reviewer. Retrieved citations were screened on title and abstract, followed by full text screening, using pre-determined inclusion and exclusion criteria. A selection of papers was reviewed by a second reviewer and discussed to reduce bias when screening. Extracted data were coded in Microsoft Excel and visualised using EviAtlas software.

Results

Data were extracted from 96 papers. Features of the studies captured included cell line, animal of origin, co-cultures, scaffold and matrix materials, media composition, culture conditions and model assessment techniques. The study identified that the main cell line used in vertebrate intestinal cell models was Caco-2, used in 78% of studies. Only 11% of studies utilised cells of non-human origin. Eighty-four per cent of studies used exclusively continuous cell lines, with the remainder using primary cell cultures or a combination of both. Models were mainly used in toxicology and pharmacology research. Techniques that could be adapted for use in salmonid cell cultures, such as immune cell co-culture and collagen matrices were identified.

Conclusions

The systematic map provides an overview of current methods in epithelial cell culture modelling. The study identified techniques and materials that can be applied to develop biologically representative salmonid intestinal cell models, reducing the need for live animals in research.

This work was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) and Harper Adams University funded Midlands Integrative Biosciences Training Partnership (MIBTP) [grant number MIBTP2022: BB/T00746X/1].

1. HENDERSON, RACHAEL, HARPER ADAMS UNIVERSITY, Presenter
2. KERSHAW, CLAIRE, HARPER ADAMS UNIVERSITY, Author
3. HERATH, THARANGANI, HARPER ADAMS UNIVERSITY, Author

Suspected jellyfish-induced intestinal pathology in sea-reared Atlantic salmon at a fjord-based research facility

Jellyfish blooms pose an unpredictable threat to global salmon aquaculture, particularly in major producing nations such as Norway and Scotland. These gelatinous organisms inflict direct harm through contact with stinging cells (nematocysts), historically linked to gill damage, respiratory distress, and mass mortalities. Effects of climate change such as eutrophication are implicated in the increased frequency and severity of blooms, heightening risks for open-net pen systems. While gill and skin pathology are well documented and usually the primary focus, impact on other organ systems such as the gastrointestinal tract has not been characterized. Here, we report novel observations of intestinal injury in Atlantic salmon (Salmo salar L.) following jellyfish exposure at a fjord-based open-net pen research station in Scotland. Starting June 2023 into mid-October, four ongoing trials at the Mowi Feed-owned Ardnish research station in Scotland were interrupted by multi-species jellyfish blooms that included Obelia spp. Feeding was stopped to prevent fish swimming to the surface and coming in contact with the jellyfish that had a persistent surface cover causing prolonged periods of fasting. All four trials were being monitored for feed-induced effects on gut health using histological assessment criteria established within our company, Aquamedic AS. Subsequent intestine samples collected from all four studies after the jellyfish bloom were observed with histopathological changes of mild to severe enteritis across all intestinal regions, i.e pyloric, mid and distal intestine. Changes were characterized by a predominantly lymphocytic infiltration of the lamina propria with occasional mucosal hemorrhaging and leiomyositis of the intestinal wall. These findings were consistent across all study groups regardless of pen, fish size and test feed. Histological findings from previous batches of intestine samples from all these studies, including a baseline sample, showed no compatibility with the post-bloom histopathological picture. These results expand the paradigm of jellyfish impacts on farmed fish, suggesting that sublethal exposure may precipitate latent intestinal pathology, even in survivors of initial gill injury. The pathophysiological mechanism of the changes observed is still unclear, but it may involve ingestion of the organisms and/or nematocyst toxins during feeding or ventilation causing direct gastrointestinal tract irritation and subsequent inflammation. Our findings suggest a redefined approach to jellyfish risk assessment, moving beyond gill-focused monitoring to include gastrointestinal health assessments and adapting feeding strategies following bloom episodes. Further research is needed to clarify the causal mechanisms behind the observed pathology.

1. Chikwati, Elvis, Aquamedic AS, Author
2. Spanos, Georgios, Aquamedic AS, Presenter
3. Berwick, Mia, Mowi Scotland, Author
4. Midtlyng, Paul J., Aquamedic AS, Author

Biosecurity in aquaculture: a practical approach for on-farm implementation

Introduction

Aquaculture continues to expand as a major source of global animal protein. However, its growth is constrained by the persistent threat of infectious diseases. Effective biosecurity measures remain key for disease prevention yet their implementation at the farm level is often inconsistent due to gaps in risk assessment, infrastructure, and practical guidance.

Methodology

We present a structured, eight-step framework for the development and implementation of On-Farm Biosecurity Plans (OFBPs), grounded in international standards (WOAH, FAO) and adapted for practical use across diverse aquaculture systems. The steps include: stakeholder engagement, production flow mapping, hazard identification and characterization, risk-based assessment, validation and monitoring, corrective actions, training and communication, and documentation. Using qualitative risk matrices and field-derived examples from marine fish, shrimp, tilapia, and salmon farming, the framework identifies critical control points and provides tools for prioritizing interventions.

Results

The application of the framework highlighted critical control points determining the pathogen introduction and spread into and within farms such as stock movement, water sourcing, equipment use and personnel access. Additional transmission vectors including live feeds, transport vehicles, birds, and rodents, are also addressed. Validation of biosecurity effectiveness can be achieved through health monitoring, biosecurity audits and performance indicators. The integration of biosecurity measures with farm-level disease surveillance and the implementation of SOPs (Standard Operating Procedures) and records can enhance compliance and traceability.

Conclusions

By framing biosecurity as a proactive investment rather than a reactive cost, this practical, research-informed model supports adoption in both resource-rich and resource-limited settings. It provides aquaculture professionals, including farmers, aquatic health specialists, researchers, and policymakers, with a comprehensive tool for enhancing disease resilience and strengthening aquatic animal health systems across the sector.

1. Picon-Camacho, Sara M., Vet’eau – Selarl du Dr Alain Le Breton, Presenter
2. Tavornpanich, Saraya, Norwegian Veterinary Institute, Author
3. Brun, Edgar, Norwegian Veterinary Institute, Author
4. Serrano De La Cruz, Maria F., Norwegian Veterinary Institute, Author
5. Zornu, Jacob, Norwegian Veterinary Institute, Author
6. Le Breton, Alain, Vet’eau – Selarl du Dr Alain Le Breton, Author
7. Le Breton, Lena, Vet’eau – Selarl du Dr Alain Le Breton, 1289 Rue des Pyrénées, 31330 Grenade Sur Garonne, France, Author

Assessing the impact of PFOS exposure on Bluegill susceptibility to Novirhabdovirus piscine

IntroductionPer- and polyfluoroalkyl substances (PFAS) have been widely employed in both industrial and household applications throughout the Great Lakes region for decades, resulting in extensive contamination of soil, water, and associated aquatic organisms. Among these, perfluorooctane sulfonate (PFOS) is one of the most frequently detected compounds and was recently designated as a hazardous substance in the United States. A particular concern is PFOS’s tendency to accumulate at high levels in fish, reflecting its strong bioaccumulative nature (e.g., PFOS in Bluegill Lepomis macrochirus sampled from Clark’s Marsh, MI reached as high as 2,450 ppb). Elevated PFOS concentrations raise serious concerns regarding potential physiological and immune system disruptions in affected organisms, including increased vulnerability to disease and decreased survival rates.MethodologyThis study explores the effects of PFOS exposure on the infection susceptibility and progression in fish, utilizing an in vitro model. Bluegill fry (BF-2) cell lines were exposed to a range of PFOS concentrations (from 0 to 10,000 ppb) for 72 hours, and cytotoxicity was comparatively assessed.BF-2 cell lines pre-treated with PFOS at concentrations of 100 and 1,000 ppb were subsequently challenged with Novirhabdovirus piscine, the etiological agent of Viral Hemorrhagic Septicaemia (VHS). Post-infection, viral replication, cytopathic effects, and the expression of key immune-related genes (Mx-1 and Type I interferon), were assessed to evaluate immunomodulatory outcomes.ResultsResults from the MTT essays indicated that PFOS exposure up to 10,000 ppb did not reduce cell viability. The highest viability (98.81±0.02%) was observed in cells exposed to 1,000 ppb, followed by those treated with 1 (97.38±0.02%), 10 (94.81±0.01%), 0 (93.62±0.02%), 10,000 (92.37±0.02%), and 100 (89.60±0.01%) ppb of PFOS.ConclusionsThis in vitro investigation offers important insights into how PFOS exposure may compromise antiviral defenses in fish inhabiting contaminated ecosystems, highlighting the broader ecological risks associated with these “forever chemicals”.

1. Adrian Deil, Manliclic, Center for PFAS Research, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI, USA, Author
2. Santosh, Lamichhane, Fish Pathobiology and Immunology Laboratory, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA, Presenter
3. GORGOGLIONE, BARTOLOMEO, Fish Pathobiology and Immunology Laboratory, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA, Author
4. Cheryl, Murphy, Center for PFAS Research, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI, USA, Author

Understanding tilapia mortalities and fish health management in Lake Volta: a systematic approach

Introduction

Unusual fish mortalities in aquaculture threaten global food security and carry significant socio-economic burdens. In 2018, Nile tilapia (Oreochromis niloticus) suffered unusual patterns of mortalities, attributed to disease-causing agents in Lake Volta cage aquaculture. In recent times, disease investigations have shifted from single to consideration of multiple factors to understand the puzzling range of causal risk factors. This study therefore aimed at expanding on tilapia mortality risk factors, while documenting fish health and Lake Volta management practices for sustainable aquaculture.

Materials and Methods

We interviewed relevant aquaculture stakeholders operating on Lake Volta and conducted thematic analysis on their responses to map out mortality risk factors and management practices. The identified risk factors were conceptualized in established models of causation web and Social-Ecological System to explain the practical significance of the findings.

Results and discussions

The results showed that the risk factors of tilapia mortalities are a combination of pathogens and non-infectious factors mediated by weak law enforcement. The results further suggested mortality reinforcing mechanisms through the horizontal transmission of pathogens, namely, Streptococcus agalactiae and Infectious Spleen and Kidney Necrosis Virus. Moreover, the recognition of weak enforcement as a possible factor reinforcing human activities is a non-infectious route that can be deleterious to fish health. Health management practices comprised phytotherapy, vaccination, heat shock treatment, biological controls, and best husbandry practices. Lake management involves creating a waterfront buffer of 85.34 m, surveillance, and executing the framework guiding aquaculture development on the Lake.

Recommendations

The findings are suggestive of complementary quantitative studies that augment the qualitative evidence herein. Such follow up studies can disclose precise mortality risk factors to inform policy directives and effective remedial strategies that can secure fish and lake health.

1. Zornu, Jacob, Norwegian Veterinary Institute, Presenter
2. Tavornpanich, Saraya, Norwegian Veterinary Institute, Author
3. Brun, Edgar, Norwegian Veterinary Institute, Author
4. van Zwieten, Paul A. M., Wageningen University and Research, Author
5. van de Leemput, Ingrid, Wageningen University and Research, Author
6. Appenteng, Patrick, Fisheries Commission, Author
7. Anchirinah, Janet, Fisheries Commission, Author
8. Cudjoe, Kofitsyo S., Norwegian Veterinary Institute, Author

Deep impact: welfare of Atlantic salmon in marine, closed confinement systems at different stocking densities

Closed cages offer the potential to solve some of the most significant challenges in large scale marine farming of Atlantic (A.) salmon (Salmo salar). The most immediate benefit is the effective prevention of sea lice infestation, thereby reducing the use of intensive delousing procedures that are detrimental to fish welfare. However, closed cages require frequent monitoring and regulation of water flow and quality. Current knowledge on how different production intensities within these systems affect water quality, fish health and welfare, and the overall production economy is limited.

In this study, we investigated the effects of two different stocking densities on A. salmon welfare by monitoring these groups over a period of eight months. Fish from four cages, two with moderate density (2 – 40 kg/m3) and two with high density (4 – 50 kg/m3), were followed from August 2024 to April 2025, with two main sampling points: four weeks after sea transfer (October 2024) and at the end of the observation period (April 2025). A combination of in-situ welfare indicators was used, including growth rate, body lesions, and gill pathology. In addition, stress levels were evaluated through plasma cortisol analysis, and gill samples were screened for pathogens. Water quality was also assessed based on flow dynamics, microbial load and physical parameters such as temperature, salinity, pH, and dissolved oxygen.

Preliminary analyses showed that fish in the moderate density cages exhibited a significantly higher condition factor (CF=1.44) and mean weight (1356 g) compared to those in high density cages (CF=1.38 and mean weight= 1242 g). Fin damage and scale loss were more pronounced in fish from the high density, potentially indicating stress-related behavioral responses. Despite these differences, no significant variation in overall health status and mortality rates was observed between the two groups. Gill health declined in all groups over time, with high prevalence of Salmon Gill Pox Virus (SGPV). By the end of the surveillance period, more extensive skin lesions were observed across all groups, associated with Moritella viscosa infection. Further investigations are required to better understand how this type of rearing environment affects fish behavior and fish health and the potential density-related differences in fish welfare. This includes histopathological analysis of gill, heart and lymphoid tissues (e.g. head kidney), assessments of water parameters, such as microbial composition, as well as transcriptional profiling of stress-related biomarkers in gills and blood samples.

1. TSOULIA, THOMAIS, NORWEGIAN VETERINARY INSTITUTE, Presenter
2. TSOULIA, THOMAIS, NORWEGIAN VETERINARY INSTITUTE, Author
3. NILSEN, ARVE, NORWEGIAN VETERINARY INSTITUTE, Author
4. KLEBERT, PASCAL, SINTEF OCEAN, Author
5. WIBORG DAHLE, STINE, SINTEF OCEAN, Author
6. TREINES, ELISABETH, AKVAFUTURE AS, Author
7. NIELSEN, KRISTOFFER VALE, NORWEGIAN VETERINARY INSTITUTE, Author
8. STORMOEN, MARIT, NORWEGIAN UNIVERSITY OF LIFE SCIENCE, Author
9. GULLA, SNORRE, NORWEGIAN VETERINARY INSTITUTE, Author
10. WALDE, CECILIE, NORWEGIAN VETERINARY INSTITUTE, Author