Over the last 12 months anaemia has emerged as a significant threat to fish health in salmon aquaculture in Scotland. Anaemia occurs when there is a lack of red blood cells, reducing the oxygen carrying capacity of the blood and negatively impacting on fish health and production. Through recent SAIC project meetings with the aquaculture partners it was highlighted that the industry has limited practical methods to define the type of anaemia occurring, identify its source and subsequently develop a preventative strategy against it. The Scottish aquaculture industry is looking to establish a haematology monitoring programme, to characterise and quantify the impact of anaemia, but does not currently have access to automated technologies for fish haematology and is reliant on slow, labour intensive and subjective manual techniques. This lack of technological advancement has also resulted in a lack of reference data for the establishment of appropriate 'normal' background levels. The overall aim of this project is the development and validation of efficient methods to assess anaemia in Atlantic salmon in aquaculture that can be adopted by the industry and included into their regular fish health management programmes. This is being undertaken by the validation of existing veterinary and medical haematology devices for assessment of fish blood, which is considerably more difficult owing to fish blood cells being nucleated. However once the relevant techniques are established and validated they shall be used to investigate anaemia in fish and to put those results into the wider context of fish health measured using high throughput, automated medical technologies to assess clinical chemistry and immunology endpoints validated for use with fish in a separate (SAIC funded) project involving the same collaborative partners. The main benefit and impact of this research shall be improvements in fish health management, increasing fish welfare and growth, subsequently benefiting the industry by a reduction in costs, increased yield and improved product quality. The development of an appropriate diagnostic system to assess anaemia in salmon aquaculture requires; a) the development and validation of rapid, automated haematological methods for salmon blood, and b) the integration of this haematology data with relevant endpoints on fish health and disease. A holistic diagnostic approach is taken, placing the haematology findings in the context of fish health investigated by the high throughput assessment of biochemistry and immunology endpoints and histological analysis. This innovative approach provides information on the cause of anaemia, thereby allowing identification of solutions. Innovation is needed in the area of blood sample preparation and storage, data interpretation and particularly with the integration of physiological impacts associated with anaemia. There is a current lack of reference values in fish haematology and this work shall contribute towards the establishment of reference data of benefit to the salmon aquaculture industry in Scotland. In the final stage of the project anaemia in Atlantic salmon from various sites around Scotland shall be identified, defined, quantified and its impact measured using haematological, clinical chemistry and immunology high-throughput analysers integrated into a pro-active mechanised technologically advanced method to assess fish heath. These techniques are relevant to the salmon aquaculture industry in the UK and internationally and user friendly practical guides and protocols shall be developed along with an engagement workshop to offer hands on training and practice to encourage the inclusion of these techniques throughout the industry, greatly increasing the impact of this research.

The rapid expansion of the global Atlantic salmon industry has been made possible through the adoption of new farming technologies (land based Recirculating Aquaculture Systems, RAS) and husbandry regimes to manipulate animal physiology. This includes the parr-smolt transformation (the process by which salmon become seawater tolerant) and early maturation impacting on fish welfare and product quality. Salmon producers in the UK have either already built or are in the process of building such large production units. These systems have clear advantages over land-based or open water loch systems, including a reduction in water usage, improved management of waste, a better control of disease and the ability to manipulate environmental conditions for year round salmon production. However, questions about robustness of these fish when exposed to challenging natural conditions in open seawater cages have been emerging over recent years, especially for gill pathologies and a new anaemic syndrome. While the Industry and Government have strong aspirations for growth of the salmon sector to meet increasing market demands, considerable pressures are being experienced by the farming companies and production, at best, has stagnated over recent years and even decreased since 2015. This is mainly due to fish health challenges at sea resulting in emergency harvests and unsustainable losses at sea. From results obtained by the consortium research teams over the past 4 years, it appears very clearly that conditions experienced by fish early during freshwater development can impact on long-term performance and robustness at sea. The current project aims to characterise the impacts of freshwater environmental conditions including water chemistry, temperature, photoperiod and nutrition, between RAS and open water loch systems, on fish performance and overall health. The main hypothesis tested by the project is that early life history of salmon produced in freshwater RAS impacts on immune barriers (mainly gill, gut and skin), which may predispose fish to gill pathologies at sea. The project will investigate how RAS microbiota (e.g. microbe populations living in the fish intestine, gill and skin) and water chemistry (especially carbon dioxide) impact on fish immune function and performance. The effects of altered environmental regimes (photoperiod, temperature and diet) and vaccines that provide active protection against particular diseases at sea, will be tested on smolt immune function, performance and health following transfer to sea. Finally, the relationship between fish development in freshwater RAS and its impact upon commercial performance and overall health will be studied including the effects of the fish genetic makeup, the characterisation of the new anaemic syndrome and a large-scale epidemiological study. To ensure the success of the project, the consortium brings together world leading scientists from four of the main UK research Institutions working on aquaculture and sustainable livestock development in conjunction with the four leading salmon farming, feed manufacturing and pharmaceutical companies. The project has also a strong support from governmental research centres and industry led organisations. The research will enable the development of practical methods for the production of high quality salmon with benefits for animal welfare and the sustainability and profitability of the industry. Since farmed salmon are a major food source in the UK diet, with more than 1.2 million salmon meals eaten per day, this project also has great significance to the health and well-being of the population in the UK. By supporting the sustainable development of the salmon farming industry, this project will contribute to protect more than 9,000 directly employed and industry-associated jobs in largely rural areas of Scotland and will help create new jobs.