Infectious diseases represent a bottleneck for the sustainable development of the aquaculture industry. They are associated with an increase of mortality, a feed conversion worsening, and a decline in animal welfare, hampering the farms’ production and their economic viability (Lama et al., 2020). Understanding the economic impact they may have is pivotal for a proper investment on health management measures. One of the most important infectious diseases in Mediterranean aquaculture is viral encephalopathy and retinopathy (VER), previously described as viral nervous necrosis (VNN). The causative agent of this disease is the nervous necrosis virus or betanodavirus (Bellance and Gallet de Saint-Aurin , 1988; Glazebrook et al, 1990; Breuil et al., 1991). Due to its virulence and rapid spreading, VER outbreaks are associated with growth reduction and high mortality of fish, affecting mostly juveniles (Vendramin et al., 2016; Lama et al., 2020; Muniesa et al., 2020). In addition, the infections of bacterial disease vibriosis, photobacteriosis and tenacibaculum spp. are also considered among the most important diseases for European sea bass (Zrncic and Pavlinec, 2020).
The aim of this work is to evaluate the direct costs of a nodavirus and vibriosis outbreak as well as their economic impact on a typical Mediterranean grow-out farm culturing European sea bass of 450g with two different sizes according to the biomass produced : small farm (540 tons/year) and large farm (2,250 tons/year ). For it, we have employed a deterministic static model proposed by Fernández Sánchez et al. (2022) as well as the economic framework proposed by McInerney et al. (1992) to evaluate the direct costs caused by these disease outbreaks (see Table 2) and their economic impact on the annual income statement of the farms (see Table 3). Our estimations show that the higher is the mortality and as the larger is the farm, the larger are the direct cost of a disease outbreak. However, the economic impact on the net operating profit is significantly worse in smaller farms, which points out the importance of investing on disease prevention and control in small scale aquaculture. Finally, we have included an estimation with the improvement of the net operating profit depending on different reductions in the disease mortality (see Table 4) to facilitate a future break-even analysis of different decisions related to the implementation of vaccination, treatments, or health management in these farms.
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Acknowledgements : This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 727315 (MedAID).