Assessment of the economic impact of disease outbreaks and mortality losses in rainbow trout aquaculture in Denmark

Disease control is one of the bottlenecks for the further development of sustainable aquaculture. Studies quantifying the economic costs of fish diseases are still inadequate because of the scarce availability of actual data. Data was collected successfully from one of the leading aquaculture companies in Denmark in this study. An investigation of the economic costs associated with mortality in rainbow trout (<i>Oncorhynchus mykiss</i>) farming on a RAS (Recirculating Aquaculture System) farm (freshwater) and a sea cage farm (saltwater) was carried out over three production cycles from 2018 to 2020. The costs associated with mortality per kg ranged from 0.22 USD to 0.50 USD in sea cage farming and 0.09 USD to 0.17 USD in the RAS facility. The findings revealed that losses of feed and biomass were responsible for the majority of the mortality cost, whereas the medication cost had a significant effect on both production facilities. The sensitivity analysis revealed that freshwater farming resulted in mortality at a low level with comparatively successful disease management, whereas once high mortality was reported, its economic impacts were expected to be substantial. In contrast, the net operating profit was robustly positive in saltwater until 57 % mortality was reached. The findings of our study emphasize the importance of maintaining robust disease control and preventing disease entry into RASs.