Norwegian salmon farming is carried out in open sea cages, which makes the interaction between farming sites and the marine environment unavoidable. In order to keep the sea lice infestations under the regulatory threshold imposed by the government, several treatments are performed, such as mechanical removal, medicine via feeding, bath treatments, and cleaner fish use (Fig. 1). This study investigates the spillover effects of neighbouring farm treatments on the farm compliance in being below the regulatory threshold. We employ spatial panel dynamic models to analyse the relationship between the proximity of farms and the incidence of sea lice infestations , focusing on the Karmøy zone in Norway.
The research identifies varying patterns of sea lice distribution across farms. Figure 1 illustrates the correlation between the types and frequencies of treatments and the levels of sea lice, establishing a baseline understanding of the infestation dynamics. The study then extends this analysis to consider the distance between farms as an additional influential factor. The inclusion of Moran’s I test for assessing spatial autocorrelation further quantifies the spatial relationships and dependencies among the variables, reinforcing the study’s focus on the spatial dynamics of sea lice infestation. However, the spillover effects from neighbouring farms treatments seem insignificant in our model.
In summary, this study provides insights into how the spacing between salmon farms might influence sea lice levels, considering the treatment practices and their effectiveness. The findings contribute to a better understanding of the complex dynamics of sea lice infestations in salmon aquaculture and underscore the importance of considering farm distribution in infestation management strategies.