Assessment of Marine Gill Disease in Farmed Atlantic Salmon (Salmo salar) in Chile Using a Novel Total Gross Gill Scoring System: A Case Study

Gill disorders have become more prevalent and widespread in finfish aquaculture in recent years. Their aetiology is often considered to be multifactorial. Effective diagnosis, control and prevention are hindered by the lack of standardised methodologies to characterise the aetiological agents, which produce an array of clinical and pathological presentations. The aim of this study was to define a novel gross pathological scoring system suitable for field-based macroscopic assessment of complex or multifactorial gill disease in farmed Atlantic salmon, using samples derived from a gill disease outbreak in Chile. Clinical assessment of gross gill morphology was performed, and gill samples were collected for qPCR and histology. A novel total gill scoring system was developed, which assesses gross pathological changes combining both the presumptive or healed amoebic gill disease (AGD) and the presence of other types of gill lesions. This scoring system offers a standardised approach to characterise the severe proliferative pathologies in affected gills. This total gill scoring system can substantially contribute to the development of robust mitigation strategies and could be used as an indicator trait for incorporating resistance to multifactorial gill disease into breeding goals.

Investigation of the transcriptomic response in Atlantic salmon (Salmo salar) gill exposed to Paramoeba perurans during early onset of disease

Amoebic Gill Disease (AGD), caused by the protozoan extracellular parasite Paramoeba perurans (P. perurans) is a disease affecting Atlantic salmon (Salmo salar). This study investigated the gill transcriptomic profile of pre-clinical AGD using RNA-sequencing (RNA-seq) technology. RNA-seq libraries generated at 0, 4, 7, 14 and 16 days post infection (dpi) identified 19,251 differentially expressed genes (DEGs) of which 56.2% were up-regulated. DEGs mapped to 224 Gene Ontology (GO) terms including 140 biological processes (BP), 45 cellular components (CC), and 39 molecular functions (MF). A total of 27 reference pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) and 15 Reactome gene sets were identified. The RNA-seq data was validated using real-time, quantitative PCR (qPCR). A host immune response though the activation of complement and the acute phase genes was evident at 7 dpi, with a concurrent immune suppression involving cytokine signalling, notably in interleukins, interferon regulatory factors and tumour necrosis factor-alpha (tnf-α) genes. Down-regulated gene expression with involvement in receptor signalling pathways (NOD-like, Toll-like and RIG-1) were also identified. The results of this study support the theory that P. perurans can evade immune surveillance during the initial stages of gill colonisation through interference of signal transduction pathways.

Shrimp farming in Southwestern Bangladesh: a case study of economic impacts during COVID-19

Bangladesh is endowed with a long coastline and therefore offers the enormous potential of marine wealth. In the coastal part of Bangladesh, shrimp is one of the most important export-oriented aquacultures due to high-profit return on the same value. Shrimp farming contributes significantly to the livelihoods of rural Bangladeshis in the southwestern region. It is critical to be aware of current culture practices and the measures shrimp farmers take to sustain the trend of exporting shrimp around the world. A random sampling was done of shrimp farmers in the Batiaghata Upazila of Khulna district to learn about the current state of shrimp farming and the challenges they are faced during COVID-19. The recent study reveals that most farmers following semi-intensive monoculture practice, application of organic sources in the shrimp pond, selection of PCR tested hatchery-produced Post Larvae (PL) and maintaining good hygiene practice that delivered considerable production of shrimp in this area. But in addition, with these good production farmers also face some difficulties. Some major shrimp diseases were identified in this study including White Feces Disease (WFD), White Spot Syndrome Virus (WSSV), Eosinophilia-Myalgia Syndrome (EMS), Black Gill Disease and some parasite attacks like Zutharium. Lower market price, flood and mortality are other constraints for shrimp farming. The low market price is the major issue for shrimp farmers nowadays around this pandemic situation. As a result, the government, donor agencies, planners, academics, and non-governmental organizations (NGOs) should come forward during the pandemic periods to assist farmers in resolving challenges and ensuring shrimp export revenues of Bangladesh are sustainable. Asian J. Med. Biol. Res. 2021, 7 (3), 273-283

Effect of aqua-drugs and chemicals on shrimp health and production in Khulna, Bangladesh

Present study was conducted in three different Upazilas viz., Batiaghata, Dacope and Rupsha of Khulna district, Bangladesh from August 2016 to May 2017. Data were collected through personal contact, farms and market survey and discussion with shrimp farmers and drug sellers. Farmers of the research areas used Oxolinic acid, Renamucin, Oxytetracucline, Lime, Salt, Formalin, Eco-solution, Basudin and Timsen to treat the viral, bacterial and fungal diseases. Average recovery of 55-60% and 35-40% were recorded from bacterial and fungal diseases of shrimp respectively, but there was no recovery in case of viral diseases. Shrimps of nontreated ghers were affected by WSSV, Black gill disease, Black spot disease, Zoothumnium and external fouling but almost no disease were observed in aqua drugs-treated ponds. Histological findings showed that shrimp muscles and hepatopancreas in drug treated ponds and ghers had some pathological changes like necrosis, vacuums and hemorrhages which were severe in winter season, whereas, normal structure of muscle and hepatopancreas were observed during summer season. Production of shrimp in the study areas was recorded 6916 Kg/ha in probiotics and aqua-drugs treated ponds, whereas, 543 Kg/ha in non-treated ghers. From the present study it could be concluded that aqua-drugs and chemicals have positive effect on shrimp health and production except some pathological changes in the investigated organgs of shrimp especially during winter season.

System Requirement Specification of Mobile Apps for shrimp farming in Shyamnagar of Bangladesh

Frozen food is one of Bangladesh’s most valuable export items, comprising more than 80% of shrimp. The most cultivated area of shrimp is situated in the southern region of Bangladesh. This research was carried out to identify the core problem in the shrimp farming areas in order to support the related farmers in seeking a solution through the most common technology used by them. The study was conducted in Shyamnagar, Satkhira district with a total of 40 female respondents involved. This research showed that shrimp farming is pressurized by a lack of proper information on disease identification and its management. Mobile apps are considered the most common information providers among that community. The research defined the common problems and necessity through the system requirement specification (SRS) to provide needed details for the farmers that focused on mobile-app development eventually. It was found that disease (82.86%) and water quality (17.14%) are the most common issues while among the diseases White Spot Syndrome Virus and Yellow Head Virus Disease followed by Black Gill disease were the most alarming to handle without pre-management knowledge. The research also suggests developing voice-based mobile apps for shrimp farmers in the local language.