The background for this proposal is the stern fact that up to 20% of farmed salmonids die every year before slaughter. Typically, episodes of mortality happen during stressful incidents and interventions such as parasite treatment, deteriorating water quality, and transport to slaughter. Large fish that die during stressful procedures before slaughter is of particular concern, considering the investment required for growing fish to this size. Obviously, such mortality is a serious welfare issue and poses a serious obstacle to sustainability, ethics and economy of the Nordic aquaculture industry.
Currently, the causes of stress-related mortality are uncertain, but an increasing body of evidence suggests that the majority die from heart failure due to abnormal heart shapes or other types of heart disease. Through on-going projects in Norway and Sweden, we have access to preliminary data that link cardiac morphology to cardiac morbidity and stress-induced mortality. In fact, deviating heart morphology also appears to restrict growth. Thus, abnormal heart shape may represent a novel and promising indicator of heart function, performance and risk of mortality. There are likely several causes underlying development of heart disease in farmed salmonids. Similar to humans, development of heart disease in fish may be linked to factors such as diet, physical activity, physical condition and stress from the environment.
The DigiHeart project, a consortium of researchers and industry partners form Norway, Sweden and the Faroe Island will develop technology and control systems that use machine learning to continuously survey data about all these factors, in addition to operational and environmental conditions to identify causes behind heart disease and mortality in farmed salmonids. The consortium will take advantage of the different production practices and prevalence of heart disease in the three countries to understand causes behind this issue. In addition, the project will develop on-site tools to evaluate mortality risk prior to stressful operational practices on fish farms. Thus, by identifying factors leading to heart disease and mortality and developing tools that can predict performance and mortality, the consortium aims at improving sustainability and animal welfare and reducing mortality in salmonid aquaculture.