What drives stocking density decisions in the Chilean salmon industry? A retrospective analysis of stocking regulations

According to Chilean legislation, a salmonid concession holder must choose between two mutually exclusive stocking density systems: Stocking Reduction Percentage (SRP) or Stocking by Density. This study identifies the main determinants in the choice of stocking system and estimates their marginal effects. The results suggest that if the previously stocked species is Atlantic salmon (Salmo salar), the probability of stocking by SRP increases by 36.6%. On the other hand, a high and medium environmental rating (determined according to mortality, use of antibiotics, and pharmacological products during the previous productive cycle) has a negative effect. At the same time, a lower rating positively impacts the choice of SRP. Whatever the selection, obtaining a poor biosecurity classification should not necessarily be interpreted as a sanction due to the fact the salmonid concession holder simply has the option to choose the other method, which would deem the policy of regulatory authority meaningless from this perspective.